What are the implications of T cells recognizing both MHC and self-antigens?
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T cells that recognize both MHC and self-antigens can cause autoimmune diseases.
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What are the implications of T cells recognizing both MHC and self-antigens?
T cells that recognize both MHC and self-antigens can cause autoimmune diseases.
Where do many phagocytes reside?
In tissue.
Which receptor binds with much stronger affinity, BCR or TCR?
BCR binds with much stronger affinity than TCR.
What part of the spleen is involved in fighting infections?
The white pulp of the spleen.
How can inflammation itself cause damage?
Through the release of toxic products and enzymes from phagocytic cells.
Where do all lymphocytes start their maturation process?
In the bone marrow.
What is the purpose of thymocyte developmental stages?
To ensure T cells can test their receptors.
What type of immune cells are macrophages?
Macrophages are innate immune cells.
What is Signal 1 in T cell activation?
The interaction of the TCR complex with MHC and antigen.
What is Signal 2 in T cell activation?
The co-stimulation signal between CD28 and B7.
What is a distinguishing property of neutrophils?
Neutrophils are short-lived.
What is the main function of CD4 TH2 Helper T cells?
To provide help for B cell antibody production, particularly IgE.
What type of structures do T cell receptors (TCR) recognize?
TCR recognize only linear peptides that are complexed with MHC.
How many antigen binding sites does the B Cell Receptor have?
The B Cell Receptor has 2 antigen binding sites.
What is required for lymphocyte activation besides antigen recognition?
Co-stimulation.
What is the role of chemokines in cell migration?
Chemokines attract other cells.
Can people without a spleen still fight blood infections?
Yes, people without a spleen can still fight blood infections.
Where does everything in the red box happen during B cell development?
In the bone marrow (B M).
Where does the last step to become fully mature occur in B cell development?
In the periphery.
What is the role of Terminal deoxynucleotidyl transferase (TdT) in gene segment combination?
TdT adds nucleotides to the ends of gene segments during the recombination process.
What does the B Cell Receptor (BCR) consist of?
The BCR consists of a membrane-bound antibody associated with signaling molecules.
Where do lymphocytes committed to the T cell lineage migrate to?
The thymus.
How do innate immune response receptors differ from adaptive immune response receptors?
Innate immune response receptors are non-clonal and not unique, whereas adaptive immune response receptors are clonal and unique.
What is immunological memory?
Immunological memory is the ability of the immune system to respond more rapidly and effectively to pathogens that have been encountered previously.
What signals guide T cell migration?
Chemokines and their receptors, as well as adhesion molecules, guide T cell migration.
Why is genetic difference important in the context of transplant rejection?
Genetic differences in antigens can cause the immune system to recognize transplanted tissue as foreign and attack it.
Do TCR and BCR work alone?
No, they require co-receptors and accessory signaling molecules for proper functioning.
What does the TCR CD3 complex consist of?
The α and β chains of the main TCR complexed with signaling proteins.
Why is inflammation around the brain and spinal cord particularly dangerous?
It can lead to meningitis.
What is positive selection in B cells tied to?
The ability of the receptor to transmit a signal.
What do CECs (Cortical Epithelial Cells) allow in thymocyte development?
They allow the expression of non-thymic antigens, such as those from other organs.
What molecules are involved in the presentation of antigens to cytotoxic T cells?
MHC class I molecules.
Which type of interferons are involved in antiviral actions?
Type I interferons.
What is the primary function of CD8 Cytotoxic T cells?
To target and kill infected cells.
What components are present on the APC for T cell activation?
MHC + Peptide, B7, Adhesion molecules (ICAM-1).
Why is it important for T cells to recognize MHC molecules?
Recognizing MHC molecules is crucial for T cells to identify and respond to antigens presented by these molecules.
What process involves the rearrangement of multiple gene segments?
Rearrangement.
Which gene segments are involved in rearrangement?
V (variable), D (diversity), J (joining), and C (constant).
What is the primary function of the spleen in relation to blood?
The spleen fights blood infections.
Where do chemokines attract cells from and to?
From blood to tissue.
How do microbes gain access to the inside of our cells?
Microbes have a variety of ways to gain access to the inside of our cells.
What is the significance of allelic variation in MHC genes?
It affects the peptide-binding region, influencing the immune response.
How do antigens arrive at the lymph nodes?
Through lymph circulation.
What process involves the combination of gene segments to generate diversity in immune receptors?
V(D)J recombination.
What happens to B cells with weak binding during selection?
They undergo ignorance or anergy.
What happens to effector cells at the end of the adaptive immune response?
Effector cells are supposed to die at the end of the response.
What is the cutaneous immune system?
The cutaneous immune system is the immune system associated with the skin, providing the first line of defense against pathogens.
Why are CTLA-4 and PD-1 important targets in cancer immunotherapy?
Blocking CTLA-4 and PD-1 can enhance T cell responses against cancer cells, making them important targets in cancer immunotherapy.
Which Toll-like Receptor (TLR) binds to peptidoglycan?
TLR 2
What is a potential consequence of a wrong immune response?
Autoimmune diseases, where the immune system attacks the body's own cells.
What enzymes are responsible for the rearrangement of gene segments?
VDJ recombinase.
What is the primary function of pro-repair macrophages?
To promote tissue repair.
What is the T cell zone in the large intestine's mucosal-associated lymphoid tissue responsible for?
Constantly testing for foreign substances.
What do cells follow during migration to an infection site?
Cells follow chemical signals, often referred to as 'bread crumbs,' to the site of infection.
What are the signaling proteins in the TCR CD3 complex collectively called?
CD3.
What happens to most lymphocytes during maturation?
Most will die and never interact with the receptor they code for.
What type of cells carry antigens to the lymph nodes from the blood?
Dendritic cells.
What process do Pro-T cells begin in the thymus?
The receptor rearrangement process.
What will a B cell try to do if its receptor is not functional?
It will try to make different types of light chains as long as the 3' end and 5' end are intact for its rearrangement.
Do innate immune response receptors have access to DNA?
Yes, innate immune response receptors have access to DNA.
What is co-receptor expression in T cells tied to?
MHC interaction.
Which cells are the first to be affected by sun exposure in the cutaneous immune system?
The first cells to be affected by sun exposure are typically skin cells, including keratinocytes and Langerhans cells.
How do CD4 TH17 Helper T cells contribute to the immune response?
They enhance the neutrophil response.
What process do Pro-B cells begin during B cell development?
The receptor rearrangement process.
What is the primary function of pro-inflammatory macrophages?
To promote inflammation.
What is the role of CD8 T cells?
CD8 T cells are cytotoxic and will kill any cell that is presenting its antigen.
Why is co-stimulation critical for lymphocyte activation?
Without co-stimulation, lymphocytes cannot be fully activated.
What type of immunity responds to intracellular microbes?
Cell-mediated immunity.
What must be done to clear an infection caused by intracellular microbes?
We must clear all microbial reservoirs, including our own infected cells.
Why doesn't bone give in to swelling during inflammation?
Because bone is rigid and does not back down to swelling.
What is the role of helper T cells in the immune response?
To assist other immune cells by releasing cytokines and enhancing the immune response.
What is T cell migration?
T cell migration is the process by which T cells move from their site of origin to various tissues in the body to perform immune functions.
What are the survival checkpoints in T cell development tied to?
The production of an intact receptor.
What do Toll-like Receptors (TLRs) and NOD-like Receptors (NLRs) trigger?
They trigger the innate immune response.
What characterizes a pro cell in lymphocyte maturation?
A pro cell in lymphocyte maturation does not yet have any part of the receptor.
Where are Gamma-Delta (γ/δ) T cells primarily found?
In the intestinal and pulmonary epithelium.
How does most of the antigen enter the body during a transplant?
Through tissue or blood.
Which Toll-like Receptor (TLR) binds to flagellin?
TLR 5
What is the function of the variable domain in lymphocyte receptors?
The variable domain is responsible for binding to antigens and varies from one receptor to another.
What is linked to the diversity of lymphocyte receptors?
Lymphocyte development.
What is the significance of the 9th stage in B cell development?
It is the stage where selection occurs.
What role do the ζ chains play in the TCR CD3 complex?
They, together with CD3, transmit the signal into the cell and initiate signal transduction.
What is the function of CTLA-4 in the immune system?
CTLA-4 is an immune checkpoint receptor that downregulates immune responses by inhibiting T cell activation.
What are the signaling molecules associated with the B Cell Receptor (BCR)?
The signaling molecules are Igα and Igβ.
What is positive selection in T cell development?
Positive selection ensures that T cells can recognize MHC molecules.
How do antibodies neutralize antigens?
By binding to them and preventing their interaction with host cells or marking them for destruction by other immune cells.
What role do CD4 TH1 Helper T cells play in the immune response?
They are pro-inflammatory, activate macrophages, and provide help for B cell antibody production.
What characterizes a pre cell in lymphocyte maturation?
A pre cell in lymphocyte maturation has one of the receptor chains.
What is the primary function of MHC molecules?
To present peptide fragments to T cells, enabling the immune system to detect and respond to pathogens.
Where does free antigen go after entering the body?
To the B cell zone.
What are the co-receptors associated with BCR?
Igα, Igβ, CD19, CD21, CD81
What is the primary intent of inflammation?
To limit damage and restore function.
What is the primary function of cytotoxic T cells?
To kill infected cells and cancer cells.
What does 'anergy' mean in the context of B cell selection?
A state where B cells exist but are never active and generally unresponsive.
What is the function of Igα and Igβ in the B Cell Receptor (BCR) complex?
Igα and Igβ transmit the signal into the cell and start signal transduction.
How are antigens related to transplant rejection?
T cell receptors recognize antigens from genetically different tissues, leading to transplant rejection.
What is the significance of the antigen-antibody binding specificity?
It ensures that antibodies can precisely target and neutralize specific pathogens without affecting the host's own cells.
Can the innate immune system remember pathogens?
No, the innate immune system does not have the ability to remember pathogens; this is a characteristic of the adaptive immune system.
What is the role of the B7 molecule in the immune system?
B7 is a costimulatory molecule found on antigen-presenting cells that binds to CD28 on T cells to provide the necessary second signal for T cell activation.
What is the function of CD4 Regulatory T cells?
To suppress T cell responses.
What happens to cancer cells when the immune system functions correctly?
Cancer cells are destroyed.
What is the significance of the variable regions in the B Cell Receptor?
The variable regions of the B Cell Receptor are crucial for antigen specificity and binding.
What is the primary movement pattern of lymphocytes in the body?
Lymphocytes constantly move from blood to lymph until they are activated or killed.
What are the co-receptors associated with TCR?
CD3, CD4, CD8
What are the constant regions in B cell development?
Y and D are constant regions.
Why is it important to know the ligand-receptor pairings in T cell activation?
Because these interactions are essential for the proper activation of T cells.
What is the primary function of the CD3 signaling proteins in the TCR CD3 complex?
To transmit the signal into the cell and initiate signal transduction.
How do antigens get processed and presented to T cells?
Antigens are processed by antigen-presenting cells (APCs) and presented on their surface bound to MHC molecules.
What is the primary role of antigens in the immune system?
To be captured and presented to T cells.
Why is T cell migration important?
T cell migration is crucial for the immune response as it allows T cells to reach sites of infection or inflammation and perform their roles in immune surveillance and response.
What is the significance of checkpoints in lymphocyte maturation?
Checkpoints ensure that only lymphocytes with functional and non-self-reactive receptors survive and mature.
What types of structures do B cell receptors (BCR) and T cell receptors (TCR) recognize?
BCR recognize 3D structures and macromolecules in their native conformation, while TCR recognize only linear peptides complexed with MHC.
What role do adhesion molecules play in T cell migration?
Adhesion molecules help T cells adhere to the endothelium of blood vessels and migrate into tissues.
What happens when an antigen enters the lymph system?
Dendritic cells present the antigen to T cells.
What percentage of adults are infected with HSV-1?
Nearly all adults are infected with HSV-1.
What are the survival checkpoints in B cell development tied to?
The production of an intact receptor.
What is the difference in dissociation constant (Kd) between BCR and TCR?
BCR has a smaller Kd compared to TCR.
What is the significance of ligand-receptor pairs in T cell activation?
They are crucial for the activation process, and it is important to know which cell each molecule is found on (T cell or APC).
What type of response can be attributed to the mild fever you get after vaccination?
The standard antiviral response.
What molecules are involved in the presentation of antigens to helper T cells?
MHC class II molecules.
What is the function of T cell receptors in the immune response?
To recognize and bind to antigens presented by other cells.
What is Signal 3 in T cell activation?
The cytokines released by the APC, which tell T_H cells what form of helper T cell to become.
How many signals are required for T cell activation?
Three signals.
What is the immune system trained not to recognize?
Our own antigens.
What is the outcome for T cells that do not recognize MHC molecules during development?
They undergo apoptosis and are removed from the T cell repertoire.
Why is recognizing self-antigens during T cell development considered bad?
Recognizing self-antigens can lead to autoimmunity, where the immune system attacks the body's own tissues.
What cytokines are involved in the differentiation of Th17 cells?
TGF-β, IL-1, IL-6, IL-23
What immunoglobulin do immature B cells express first?
IgM alone.
What must pathogens have to temporarily pass the immune response?
A tool that allows them to pass the immune response temporarily.
What is an analogy used to describe cell migration?
An aircraft stopping dead on an aircraft carrier.
What are the consequences of inflammation in delicate systems?
The consequences are more severe, such as inflammation around the brain and spinal cord leading to meningitis.
Why is bacterial meningitis considered very dangerous?
It can cause long-term brain damage.
What is the role of effector cells in the adaptive immune response?
Effector cells perform their specific functions to eliminate pathogens.
What role does PD-1 play in the immune system?
PD-1 is an immune checkpoint receptor that inhibits T cell activity to prevent autoimmunity and reduce inflammation.
Where are innate immune response receptors located?
Innate immune response receptors are located everywhere in the body.
Which molecules in the B Cell Receptor (BCR) complex are similar to CD3 in their function?
Igα and Igβ are similar to CD3 in their function of transmitting signals into the cell.
Where do T cells originate and mature?
T cells originate in the bone marrow and mature in the thymus.
What are the components of the B Cell Receptor (BCR)?
The BCR consists of 2 heavy chains and 2 light chains.
Where do lymphocytes committed to the B cell lineage develop?
In the bone marrow.
Which cytokine is crucial for the differentiation of Th2 cells?
IL-4
What does the expression of co-receptors indicate?
The developmental stage of the cell.
When do antigen-specific B/T cells arise?
Before encounter with antigen.
What happens if inflammation is limited to the injured area?
The damage is usually nominal.
What enzyme is involved in the addition of nucleotides during gene segment combination?
Terminal deoxynucleotidyl transferase (TdT).
Which T cell chain undergoes gene segment recombination second?
The α chain.
What is receptor editing in lymphocyte maturation?
Receptor editing is a process during lymphocyte maturation where the cell changes its receptor to avoid self-reactivity.
What are antigens?
Molecules or molecular structures that are recognized by antibodies and trigger an immune response.
What happens to T cells that cannot recognize MHC molecules during positive selection?
They are eliminated because they cannot effectively participate in the immune response.
What role does the cutaneous immune system play?
It acts as the first line of defense against pathogens entering through the skin.
What is the major histocompatibility complex (MHC)?
A set of genes that code for proteins on the cell surface which help the immune system recognize foreign substances.
What is the job of the immune response?
To clear the foreign antigen and its source.
What is cell migration?
Cell migration is the process by which cells move from one location to another, often following chemical signals.
What is the adaptive immune response capable of handling simultaneously?
Multiple antigens at the same time.
Which cells are involved in the ligand-receptor interactions for T cell activation?
T cells and Antigen-Presenting Cells (APCs).
What is negative selection in B cells tied to?
High affinity binding in primary lymph tissue.
What is the primary function of antibodies?
To bind to antigens and neutralize them or mark them for destruction by other immune cells.
What happens to lymphocytes that fail multiple checkpoints during maturation?
Lymphocytes that fail multiple checkpoints during maturation undergo apoptosis (cell death).
What are the stages of T cell development in relation to co-receptor expression?
Double-negative, double-positive, and single-positive.
What type of bacteria are Escherichia, Salmonella, and Shigella?
They are Gram-negative bacteria.
What type of structures do B cell receptors (BCR) recognize?
BCR recognize 3D structures and macromolecules in their native conformation.
What are the two main types of macrophage activation?
Pro-inflammatory and pro-repair.
What are the two main domains of lymphocyte receptors?
The variable domain, responsible for binding to antigens, and the constant domain, responsible for structural and effector functions.
What is considered foreign by the immune system?
Any antigen that is not our own or wasn’t screened for.
What is the function of the constant domain in lymphocyte receptors?
The constant domain is structural and responsible for effector functions, and is virtually the same from one receptor to another.
What are the main cell types found in lymph nodes?
Macrophages and plasma cells.
What are some functions of Gamma-Delta (γ/δ) T cells?
Functions include tumor destruction, recognition of heat-shock proteins on damaged or infected cells, and epithelial surveillance for UV damage, infection, and cancer.
What can result from a hyperactive immune response?
Chronic inflammation and tissue damage.
What is the significance of V(D)J recombination in B cells?
V(D)J recombination generates the diversity of antibodies necessary for the immune system to recognize a wide array of antigens.
When are B-1 cells formed?
Early in life.
Why is microbial resistance important for pathogens?
It allows them to temporarily evade the immune response.
Where is the variability mainly found in MHC genes?
In the peptide-binding region.
Can the adaptive immune response deal with different infections simultaneously? Provide an example.
Yes, it can deal with different infections simultaneously, such as responding to COVID-19 and Hepatitis B at the same time.
Which T cell chain undergoes gene segment recombination first?
The β chain.
What is the role of the autoimmune regulator (AIRE) in thymocyte development?
AIRE allows CECs to express non-thymic antigens.
What are the common properties of neutrophils and monocytes?
Both are phagocytes.
How do CTLA-4 and PD-1 contribute to immune tolerance?
Both CTLA-4 and PD-1 help maintain immune tolerance by inhibiting T cell activation and preventing overactive immune responses.
What is negative selection in T cell development?
Negative selection eliminates T cells that recognize self-antigens presented by MHC molecules.
What components are present on the T cell for activation?
T Cell Receptor including CD3 and CD4/8, CD28, Integrins (LFA-1).
Which Toll-like Receptor (TLR) binds to lipopolysaccharides?
TLR 4
What percentage of total T cells do Gamma-Delta (γ/δ) T cells constitute?
Approximately 10% of total T cells.
What is the role of CD4 T cells?
CD4 T cells are helper T cells and will tell other cells what to do.
What is an allergic reaction?
An exaggerated immune response to a harmless substance.
What is the source of receptor diversity in lymphocytes?
The rearrangement of gene segments that encode receptor proteins.
What dual expression do B cells exhibit as they develop?
IgM and IgD.
Where does the final maturation step of B cells occur?
In the periphery.
What percentage of adults are infected with Epstein-Barr virus?
Nearly all adults are infected with Epstein-Barr virus.
What are the main types of Helper T cells to know?
Th1, Th2, Th17
What does CTL stand for?
Cytotoxic T Lymphocyte.
Name a key cytokine involved in innate immunity.
Interleukin-1 (IL-1) is a key cytokine involved in innate immunity.
What is unique about each T cell in our bodies?
Each T cell recognizes something completely different from all of the others.
What is negative selection in T cell development?
Negative selection eliminates T cells that strongly bind to self-antigens, preventing autoimmunity.
What are some outcomes when the immune system works properly?
We are protected against pathogens, can fight off infection, cancer cells are destroyed, and we recognize and ignore harmless antigens.
What are phagocytes?
Specialized cells that engulf and digest microbes and cellular debris.
What is the significance of peptide binding to MHC molecules?
Peptide binding to MHC molecules is crucial for the immune system to recognize and respond to pathogens.
What occurs after T cells are activated by dendritic cells?
Activated T cells proliferate and become effector cells.
What can potentially trigger an immune response?
A foreign antigen.
How are alleles from both parents used in MHC molecule expression?
Both maternal and paternal alleles are expressed, contributing to the diversity of MHC molecules.
What is junctional diversity?
Adding or deleting nucleotides at the junction site of different segments.
What triggers the acute inflammatory response?
The entry of bacteria into the body.
How does cell-mediated immunity differ from humoral immunity?
Cell-mediated immunity involves T cells and does not rely on antibodies, whereas humoral immunity involves B cells and the production of antibodies.
What is the name of the region in the lymph node where B cells are active and dividing?
The follicle.
What enzyme complex is crucial for V(D)J recombination in B cells?
The RAG (Recombination Activating Gene) enzyme complex.
What ligands do activated T cells express?
The ligand for E and P-selectin and the integrins LFA-1 and VLA-1.
What are the two main functional domains of an antibody?
The Fab fragment and the Fc fragment.
Where does translation occur in the cell?
In the cytoplasm.
How do activated T cells contribute to the immune response?
Activated T cells secrete cytokines that help regulate and amplify the immune response.
What role do cytokines play in CTL activation?
Cytokines such as IL-2, produced by helper T cells, promote the proliferation and differentiation of CTLs.
What type of molecules do MHC molecules typically bind to?
MHC molecules typically bind to protein peptides.
What are some key signals that direct cell migration?
Chemokines and cytokines are key signals that direct cell migration.
What is receptor gene expression?
Receptor gene expression refers to the process by which specific genes are transcribed and translated to produce receptor proteins on the surface of cells.
What are the receptors on B cells and T cells made of?
Proteins.
What is the challenge regarding the coding of so many receptors by a limited genome?
How so many receptors are coded for by such a limited genome.
What is the significance of MHC class I molecules in cell-mediated immunity?
They present intracellular antigens to cytotoxic T cells, triggering an immune response.
What happens to the thymus as we age?
The thymus undergoes involution, meaning it gradually shrinks and becomes less active in producing new T cells.
Which antibody isotype is primarily found in mucosal areas and body secretions like saliva, tears, and breast milk?
IgA.
What is the primary function of macrophages?
The primary function of macrophages is to phagocytose (engulf and digest) pathogens, dead cells, and cellular debris.
Can you name a common second messenger involved in signal transduction?
Cyclic AMP (cAMP) is a common second messenger.
Can all MHC molecules present antigens to T cells?
Yes, but each MHC molecule binds a different range of peptides.
How does mucus contribute to the immune defense?
Mucus is driven upward constantly to expel or swallow it, trapping and protecting against pathogens.
Which antibody isotype is involved in allergic reactions and protection against parasitic infections?
IgE.
How do cells communicate with each other and the environment?
Cells communicate through receptors that recognize and bind molecules called ligands.
What happens when a T cell recognizes both antigen and MHC?
The T cell will activate and become an effector cell.
What role do dendritic cells play in cell-mediated immunity?
They present antigens to T cells.
How do MHC molecules contribute to immune responses?
By presenting antigens to T cells, which then initiate an immune response against the detected pathogen.
What needs to happen to the antigen when it enters the body?
It needs to get to the secondary lymphoid organs.
How does the immune system handle harmless antigens when it is functioning properly?
It recognizes and ignores them.
What is the typical length of peptides that bind to MHC molecules?
10-30 amino acids.
What role do macrophages play in antigen presentation?
Macrophages engulf pathogens, process them, and present antigens to T cells.
What is a common characteristic of Herpes simplex virus, Cytomegalovirus, and Epstein-Barr virus?
They all have high infection rates among adults.
What triggers the expansion of T cells?
The recognition of antigens by T cell receptors (TCRs) triggers the expansion of T cells.
What is the first signal required for CTL activation?
Recognition of antigen presented by MHC class I molecules on the surface of infected or abnormal cells.
What does the endothelium express upon cytokine direction?
High levels of E-selectins, P-selectins, ICAM-1, and VCAM-1.
What is signal transduction?
Signal transduction is the process by which a cell converts an extracellular signal into a functional response.
What is an immunological synapse?
An immunological synapse is the interface between an antigen-presenting cell (APC) and a T cell where signaling and communication occur.
Are normal microbiota technically part of the immune system?
No, but they provide significant protection.
Which cells are involved in forming an immunological synapse?
An antigen-presenting cell (APC) and a T cell.
What is the most difficult barrier for pathogens to penetrate?
The skin.
What is the primary function of the immunological synapse?
To facilitate communication and signaling between the antigen-presenting cell and the T cell, leading to T cell activation.
Why do lymph nodes swell during an immune response?
Lymph nodes swell because B and T cells are cloning (proliferating) in response to recognizing an antigen.
How do normal microbiota protect the body?
Through competitive exclusion by covering binding sites and competing for nutrients.
How do dendritic cells capture antigens?
Through phagocytosis, endocytosis, and pinocytosis.
In what conditions is T cell exhaustion commonly observed?
T cell exhaustion is commonly observed in chronic infections and cancer.
What role do integrins play in cell migration?
Integrins are cell surface receptors that mediate adhesion to the extracellular matrix, facilitating cell movement.
What is the role of mucus in mucous membranes?
Mucus helps wash surfaces and can propel microorganisms and viruses to areas where they can be eliminated.
What are Langerhans cells?
A specialized type of dendritic cell found in the skin.
What happens if CD4 T cells are not present to assist CD8 T cells?
Without CD4 T cell help, CD8 T cells may have a reduced ability to proliferate and effectively kill target cells.
What are the main components of the lymphoid system?
Lymphatic vessels, primary (generative) lymphoid organs, and secondary (peripheral) lymphoid organs.
Why is signal transduction important for cells?
Signal transduction is important because it allows cells to respond to their environment and communicate with other cells, ensuring proper functioning and coordination within an organism.
What role do Helper T cell cytokines play in macrophage activation?
Helper T cell cytokines, such as Interferon-gamma (IFN-γ), activate macrophages to enhance their microbicidal activity.
What are pyrogens?
Substances that induce fever.
What is the function of CD28 in T cell activation?
CD28 is a receptor on T cells that binds to B7 on antigen-presenting cells, providing a crucial costimulatory signal required for full T cell activation and survival.
Where does the other part of the antigen go after entering the body?
To the T cell zone.
Which genes produce the VDJ recombinase enzymes?
Recombinase-activating Genes (RAG-1 and RAG-2).
What is gene segment recombination in B cells?
Gene segment recombination is the process by which B cells rearrange their DNA to create unique antibodies.
Which cells are primarily involved in cross-presentation?
Dendritic cells.
What is the region in the lymph node where T cells are primarily located?
The T cell zone.
How does IL-2 contribute to the immune response?
IL-2 promotes the proliferation of activated T cells, enhancing the immune response.
What is the length of the core region of peptides that bind to MHC molecules?
8-11 amino acids.
What role do cytokines play in the acute inflammatory response?
Cytokines recruit more immune cells to the site of infection.
How does IL-2 affect natural killer (NK) cells?
IL-2 enhances the cytotoxic activity of natural killer (NK) cells.
What is the role of MHC in antigen presentation?
MHC molecules present microbial antigens to effector cells for recognition.
What happens to T cells after the antigen is eliminated?
After the antigen is eliminated, most of the expanded T cells undergo apoptosis, leading to a decline in their numbers.
What are the two main types of T Cell Receptors?
The two main types of T Cell Receptors are alpha-beta (αβ) TCRs and gamma-delta (γδ) TCRs.
What is the function of the Fab fragment in an antibody?
It binds to the antigen.
How do chemokines function in innate immunity?
Chemokines attract immune cells to sites of infection or injury.
What unique capability do dendritic cells have that other APCs do not?
They can both present antigens and phagocytose.
What is the difference between MHC class I and MHC class II molecules?
MHC class I molecules present endogenous antigens (from within the cell) to CD8+ T cells, while MHC class II molecules present exogenous antigens (from outside the cell) to CD4+ T cells.
How do CTLs recognize infected or cancerous cells?
By detecting specific antigens presented on the surface of these cells by MHC class I molecules.
How do cells move during migration?
Cells move by extending protrusions like lamellipodia and filopodia, adhering to the extracellular matrix, and contracting their cytoskeleton to pull themselves forward.
What happens to dendritic cells after they capture an antigen?
They migrate to the lymph nodes where they present the antigen to T cells.
How does covering binding sites by normal microbiota protect the body?
It prevents pathogens from binding.
What are the two main functions a lymphocyte receptor must perform?
Name a key cytokine produced by Helper T cells.
Interleukin-2 (IL-2) is a key cytokine produced by Helper T cells.
How does competition for nutrients by normal microbiota protect the body?
It makes nutrients unavailable for pathogens.
What is the significance of MHC class I molecules in CTL activity?
They present antigens to CTLs, allowing them to recognize and target infected or abnormal cells.
How does T cell activation affect B cells?
It regulates B cell activity
What are the regions of high variability within the variable domains called?
Hypervariable Regions (HV) or Complementarity Determining Regions (CDR).
What is the significance of dendritic cells in vaccine development?
They are crucial for inducing a strong and specific immune response, making them a target for vaccine strategies.
Which white blood cells are considered part of the innate response?
All white blood cells except most lymphocytes.
What can happen if the immune system fails to respond to a pathogen?
Infection and disease, as the pathogen can proliferate unchecked.
What are professional antigen-presenting cells (APCs)?
Cells that present antigens to T cells to activate an immune response.
What is the process of combining different gene segments called?
Combinatorial diversity.
How are the genes that encode receptor proteins structured in the germline?
They are segments, not complete genes.
What happens to lymphocytes if they are not activated?
They continue to move between blood and lymph until they are either activated or killed.
What is the first step that occurs after T cell activation?
T cells undergo clonal expansion, where they rapidly proliferate to increase the number of T cells specific to the antigen.
How many copies or alleles do diploid cells have for each gene?
Two copies or alleles.
What role do cytokines play in innate immunity?
Cytokines mediate and regulate immune and inflammatory responses in innate immunity.
How do MHC molecules present antigens?
MHC molecules present antigens in a membrane-bound form.
What mechanisms are in place to prevent dual expression of alleles in lymphocytes?
Mechanisms built in to ensure that each lymphocyte expresses only one antigen-specific receptor.
What does the Fab fragment of an antibody consist of?
An entire light chain and the corresponding heavy chain variable region and first constant region.
Why is cell migration important in the immune system?
Cell migration is crucial for immune responses, allowing immune cells to travel to sites of infection or injury to perform their functions.
What is the result of allelic exclusion in terms of receptor expression?
Each lymphocyte will express either all maternal or all paternal receptors, but not a mix.
What cytokine is predominantly produced by Th1 cells?
Interferon-gamma (IFN-γ).
What are common features of exhausted T cells?
Common features include poor effector function, sustained expression of inhibitory receptors (such as PD-1, CTLA-4), and a distinct transcriptional profile.
What is the primary function of Th2 cells?
Th2 cells are involved in humoral immunity and help activate B cells to produce antibodies.
Why is MHC polymorphism important for the immune system?
MHC polymorphism increases the range of antigens that can be presented to T cells, enhancing the ability of the immune system to recognize and respond to a diverse array of pathogens.
What is the function of the Fc fragment in an antibody?
It determines the class and effector functions of the antibody.
What type of responses are stimulated as a result of T cell activation?
Both innate and adaptive responses
What is the primary function of Th17 cells?
Th17 cells are involved in the defense against extracellular bacteria and fungi and contribute to inflammatory responses.
What happens to monocytes after they leave the bone marrow?
After leaving the bone marrow, monocytes circulate in the blood and then migrate into tissues where they differentiate into macrophages or dendritic cells.
What cytokine is predominantly produced by Th17 cells?
Interleukin-17 (IL-17).
Why is it important for immune cells to encounter antigens?
In order for the body to mount an appropriate immune response.
What segments do the heavy-chain (BCR) and β-chain (TCR) have?
V, D, and J segments.
What activity is enhanced as a result of T cell activation that involves killing infected cells?
CTL (Cytotoxic T Lymphocyte) activity
How do dendritic cells activate T cells?
By presenting processed antigens on their surface along with necessary co-stimulatory signals.
What is the sequence of rearrangement for heavy-chain (BCR) and β-chain (TCR)?
D-J rearrangement first, then V-DJ.
Where do T cells become fully mature?
T cells become fully mature in the thymus.
At what level does the D-J and V-DJ rearrangement occur?
At the DNA level.
What is unique about the γ/δ TCR's repertoire?
It has a restricted repertoire and may recognize antigens without MHC restriction.
What types of antigens can γ/δ T cells recognize?
They can recognize non-peptide antigens.
Which cells are considered professional antigen-presenting cells?
Dendritic cells, B cells, and macrophages.
Which cells are primarily involved in cell-mediated immunity?
Phagocytes, antigen-specific cytotoxic T-lymphocytes, and various cytokines.
Does receiving a second shot guarantee that you won't get sick?
No, receiving a second shot doesn't mean you won't get sick.
What type of infection does the T cell response target in adaptive immunity?
Intracellular infection.
What is the function of phagolysosomes?
They are where the microbiome is chopped.
Which cells are primarily involved in the extracellular response of adaptive immunity?
B cells.
Can a cell express both alleles of a gene simultaneously?
No, unlike MHC, a cell can only express one allele.
What is the function of the germinal center in the lymph node?
It is the site where B cells proliferate, differentiate, and mutate their antibody genes.
What is the function of the MHC molecule's binding zone?
The binding zone of the MHC molecule holds the antigen in place so it doesn't fly away.
What is polygeny in the context of the immune system?
Polygeny refers to the presence of multiple genes within an individual that encode for proteins with similar functions, such as the multiple MHC (Major Histocompatibility Complex) genes.
What are double-positive T cells?
T cells that express both CD4 and CD8 co-receptors during a stage of their development.
What is the role of memory T cells?
Memory T cells persist after the decline phase and provide a faster and more robust response upon re-exposure to the same antigen.
What are mononuclear phagocytes?
Mononuclear phagocytes are a type of immune cell that includes monocytes and macrophages, which are involved in the detection, phagocytosis, and destruction of bacteria and other harmful organisms.
What is the role of the Major Histocompatibility Complex (MHC) in TCR function?
The Major Histocompatibility Complex (MHC) presents peptide fragments of antigens on the surface of antigen-presenting cells, which are then recognized by T Cell Receptors (TCRs).
Where do almost fully mature T cells go after leaving the thymus?
They enter the peripheral bloodstream and lymphoid organs to perform immune functions.
What types of cells are involved in MHC-associated antigen presentation?
Effector cells, such as T cells, are involved in MHC-associated antigen presentation.
What is the two-signal requirement for lymphocyte activation?
The two-signal requirement for lymphocyte activation involves the recognition of an antigen by the lymphocyte receptor (Signal 1) and a co-stimulatory signal provided by antigen-presenting cells (Signal 2).
What happens to the S1P receptor expression when it binds to its cellular receptor?
Binding to its cellular receptor reduces the expression of the S1P receptor.
How do CD4 T cells assist CD8 T cells?
CD4 T cells secrete cytokines that enhance the activation and proliferation of CD8 T cells.
How does receptor gene expression contribute to the diversity of the immune response?
Receptor gene expression involves genetic recombination processes that generate a diverse repertoire of receptors, enabling the immune system to recognize a wide array of antigens.
What immune response is associated with T cell activation and involves redness and swelling?
Inflammation
What is the primary function of Treg cells?
Treg cells help maintain immune tolerance and prevent autoimmune diseases.
What is one of the strongest indicators of infection?
Fever.
What cytokine is predominantly produced by Treg cells?
Transforming growth factor-beta (TGF-β) and Interleukin-10 (IL-10).
Can CD8 T cells function independently of CD4 T cells?
While CD8 T cells can function independently to some extent, their efficiency and longevity are significantly enhanced by the help of CD4 T cells.
What is the role of the main receptor in lymphocyte receptors?
The main receptor binds the ligand.
How does the size of the B Cell Receptor compare to the T Cell Receptor (TCR)?
The B Cell Receptor is approximately twice as large as the T Cell Receptor.
What is polymorphism in the context of MHC molecules?
Polymorphism refers to the presence of multiple alleles at a gene locus, resulting in a high degree of variability in MHC molecules.
What do effector cells do after they are formed?
They go to the site with the source of the activating antigen and carry out their effector functions.
Which cytokines are important for the differentiation of Th1 cells?
IL-12 and IFN-γ
How do B cells function as antigen-presenting cells?
B cells present antigens to T cells to help initiate an immune response.
What happens to T cells in the thymus during their development?
They undergo a series of maturation steps, including positive and negative selection.
Do all cells with a nucleus have MHC class I molecules?
Yes, every single cell with a nucleus has MHC class I molecules.
Which type of cells do not have MHC class I molecules?
Red blood cells (RBCs).
What is clonal expansion in the context of T cells?
Clonal expansion refers to the rapid multiplication of T cells that have recognized a specific antigen.
What is cell migration?
Cell migration is the process by which cells move from one location to another, often in response to specific signals.
Where are viral and intracellular bacterial antigens located within the cell?
In the cytoplasm.
How do B cells recognize antigens?
By the B cell receptor (BCR).
What does the TCR complex engage for T cell activation?
MHC + peptide
How does the immune system ensure that T cell numbers return to normal after an infection?
The immune system induces apoptosis in most of the expanded T cells, ensuring that their numbers return to normal after the infection is cleared.
Which cells are primarily involved in cell migration during an immune response?
Leukocytes, including T cells, B cells, and macrophages, are primarily involved in cell migration during an immune response.
Why is receptor gene expression important in the immune system?
Receptor gene expression is crucial for the development and function of immune cells, allowing them to recognize and respond to specific antigens.
Which inhibitory receptors are commonly expressed by exhausted T cells?
PD-1 and CTLA-4 are commonly expressed inhibitory receptors on exhausted T cells.
What cytokines are predominantly produced by Th2 cells?
Interleukin-4 (IL-4), Interleukin-5 (IL-5), and Interleukin-13 (IL-13).
Which cells are primarily involved in receptor gene expression in the immune system?
B cells and T cells are primarily involved in receptor gene expression, producing B cell receptors (BCRs) and T cell receptors (TCRs) respectively.
What is the primary function of the lymphoid system?
To bring B and T cells in contact with antigens.
What initiates signal transduction?
A signal, often in the form of a molecule such as a hormone or neurotransmitter, initiates signal transduction.
What type of cells do NK cells target and kill?
NK cells target and kill cells that are abnormal or infected, not microbes directly.
What are the three types of B cells?
B-2 cells (Follicular B cells), B-1 cells, and Marginal zone B cells.
What is the role of receptor gene expression in lymphocyte maturation?
During lymphocyte maturation, receptor gene expression ensures that each lymphocyte expresses a unique receptor, which is essential for the specific recognition of antigens.
Which organs compensate for the reduced activity of the thymus in T cell production?
Other lymphoid organs, such as the spleen and lymph nodes, help compensate for the reduced activity of the thymus.
How do activated T cells eventually leave the lymph node?
S1P receptor expression is restored while L-selectin and CCR7 are turned off, drawing the activated cell out of the lymph node.
How do normal microbiota help teach our immune response?
They help teach our immune response what is good and bad.
What cells mediate T cell positive and negative selection?
Thymic cortical epithelial cells.
Why is the interaction between B7 and CD28 important?
The interaction between B7 and CD28 is essential for the activation of T cells, as it provides the necessary costimulatory signal that complements the antigen-specific signal from the T cell receptor.
What is cell-mediated immunity?
Cell-mediated immunity is an immune response that does not involve antibodies but rather the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.
Which gene segments are involved in B cell recombination?
The V (variable), D (diversity), and J (joining) gene segments.
How do pro-inflammatory and pro-repair macrophages interact with each other?
They inhibit each other as they have opposing functions.
Where do effector T cells migrate?
To the site of infection.
What is the function of lysozyme?
Lysozyme degrades peptidoglycan.
What is the significance of MHC class I molecules in cell-mediated immunity?
They present intracellular antigens to cytotoxic T cells, triggering an immune response.
Which types of molecules often do not induce a strong immune response?
Lipids and nucleic acids.
How do T cells recognize antigens?
Through T cell receptors (TCRs) that bind to specific antigens presented by MHC molecules.
Where are the chemokines that bind CCR7 produced?
Only in lymph tissues.
How do T cells and B cells recognize specific antigens?
T cells recognize antigens presented by other cells via MHC molecules, while B cells recognize free-floating antigens directly.
Can both organic and inorganic compounds elicit an immune response?
Yes, both organic and inorganic compounds can elicit an immune response.
What is the role of Th1 cells?
Th1 cells are involved in cell-mediated immunity and help activate macrophages and cytotoxic T cells.
What triggers the activation of NK cells?
NK cells are activated by the presence of stress-induced ligands on target cells and the absence of MHC class I molecules.
What is the primary characteristic of adaptive immunity?
Adaptive immunity provides a specific response to pathogens and has memory for faster response upon re-exposure.
When do antigen-specific cells arise?
Before exposure to the antigen.
What is the most important receptor:ligand interaction in immunology?
The T cell receptor:MHC/antigen interaction.
What are the consequences of cytokine production and expression of selectins and ICAMs?
Cell migration, inflammation, and activation of the adaptive response.
What is the second letter of the Greek alphabet?
Beta (Β, β)
What is the role of regulatory T cells (Tregs) in the immune system?
Regulatory T cells (Tregs) help maintain immune tolerance and prevent autoimmune responses by suppressing the activity of other immune cells.
What is the twenty-third letter of the Greek alphabet?
Psi (Ψ, ψ)
What percentage of adults in the United States are infected with HSV-2?
Approximately 20% to 50% of adults in the United States are infected with HSV-2.
What is cross-presentation?
Cross-presentation is the process by which certain antigen-presenting cells, like dendritic cells, present exogenous antigens on MHC class I molecules.
What is the primary function of dendritic cells?
To present antigens to T cells and activate them.
What is the first step in T cell development?
T cell progenitors migrate from the bone marrow to the thymus.
Why is the rearrangement of gene segments important for the immune system?
It is the source of lymphocyte receptor diversity.
What is positive selection in T cell development?
Positive selection ensures that T cells can recognize self-MHC molecules.
What is the function of Interleukin-1 (IL-1) in innate immunity?
IL-1 promotes inflammation and the activation of immune cells.
Which cells are primarily involved in cell-mediated immunity?
T cells, including cytotoxic T cells (CD8+) and helper T cells (CD4+).
How are MHC molecules typically viewed in terms of structure?
MHC molecules are often viewed from a top-down perspective to understand where the antigen binds.
What is polymorphism in the context of the immune system?
Polymorphism refers to the existence of multiple alleles or variants of a gene within a population, leading to genetic diversity in MHC molecules.
What does CTL stand for in immunology?
Cytotoxic T Lymphocyte.
What role do helper T cells (CD4+) play in cell-mediated immunity?
They assist other immune cells by releasing cytokines that enhance the immune response.
What role do receptors play in signal transduction?
Receptors bind to signaling molecules (ligands) and initiate the signal transduction process.
What happens to CTLs after they are fully activated?
They proliferate and differentiate into effector CTLs capable of killing infected or abnormal cells.
What is signal transduction?
Signal transduction is the process by which a signal is transmitted through a cell as a series of molecular events, typically involving protein phosphorylation, leading to a cellular response.
How are the receptors on lymphocytes coded for?
By the genome.
What does TH1 stand for in immunology?
TH1 stands for T helper type 1 cells.
What is the primary function of Helper T cell cytokines?
The primary function of Helper T cell cytokines is to regulate and coordinate the activities of other immune cells.
What is the role of dendritic cells in adaptive immunity?
They present antigens to T cells, thus bridging the innate and adaptive immune responses.
What are the two types of immune responses?
Primary and secondary immune responses.
Which antibody isotype is the first to be produced in response to an infection and is effective in forming antigen-antibody complexes?
IgM.
What is inflammation?
The body’s response to tissue damage or microbial invasion.
What characterizes the primary immune response?
The primary immune response occurs when the immune system encounters an antigen for the first time, leading to a slower and less intense response.
Which cytokine is crucial for the differentiation of naive T cells into Helper T cells?
Interleukin-12 (IL-12) is crucial for the differentiation of naive T cells into Helper T cells.
What is the role of MHC in T cell selection?
It dictates co-receptor expression and is essential for positive selection.
What does the innate immune response recognize and attack?
Common features of microorganisms called Pathogen Associated Molecular Patterns (PAMPs).
When do light-chain (BCR) and α-chain (TCR) rearrangements occur?
After successful heavy-chain (BCR) and β-chain rearrangements.
What does the term 'antigen' originally stand for?
Anti body gen erator, a compound that elicits antibody production.
Does every immune response require the adaptive immune system?
No, not everything needs the adaptive response.
What is immunodeficiency?
A condition where the immune system's ability to fight infectious disease is compromised or entirely absent.
What type of infection does the B cell response target in adaptive immunity?
Extracellular infection.
From where can additional phagocytes be recruited?
From the bloodstream and bones.
What process creates a complete, linear gene sequence for receptor proteins?
Random rearrangement of multiple gene segments.
At what stage of B cell development does gene segment recombination occur?
Gene segment recombination occurs during the early stages of B cell development in the bone marrow.
What role does IL-2 play in regulatory T cells?
IL-2 is crucial for the survival and function of regulatory T cells, which help maintain immune tolerance.
What happens after cytokines recruit more cells during an acute inflammatory response?
More cells bind to the vessel surface and enter the tissue.
What is the significance of memory T cells?
Memory T cells provide long-term immunity by remaining in the body and responding more rapidly and effectively if the same antigen is encountered again.
Which cytokine is known for its antiviral properties in innate immunity?
Interferon-alpha (IFN-α) is known for its antiviral properties.
Which cells are involved in the humoral response?
B cells.
What activates Natural Killer (NK) cells?
Macrophages ingest pathogens and release signals that activate NK cells.
What happens to most effector T cells after the infection is cleared?
Most effector T cells undergo apoptosis (programmed cell death) after the infection is cleared to prevent excessive immune response.
Where are excreted proteins or those bound for cell surface attachment processed?
In the endoplasmic reticulum (ER).
What is the primary function of Cytotoxic T Lymphocytes (CTLs)?
To kill infected or cancerous cells.
Where are dendritic cells commonly found in the body?
In tissues that are in contact with the external environment, such as the skin (Langerhans cells) and the inner lining of the nose, lungs, stomach, and intestines.
How does perspiration contribute to the skin's defense against pathogens?
Perspiration contains salt which inhibits pathogen growth and antimicrobial substances.
How are cells or cell parts (pathogens) internalized into the cell?
By endocytic vesicles.
What is the role of IFN-γ released by NK cells?
IFN-γ helps activate macrophages and assists CD8+ T cells in killing infected cells.
How do the proportions of naive and memory T cells change with age?
With age, the proportion of naive T cells decreases while the proportion of memory T cells increases.
How many reading frames are possible for a given nucleotide sequence?
There are three possible reading frames for a given nucleotide sequence, depending on the starting point.
Which chains undergo rearrangement first in BCR and TCR?
Heavy-chain (BCR) and β-chain (TCR).
What is the significance of cytokines in the cooperation between CD4 and CD8 T cells?
Cytokines produced by CD4 T cells help in the activation, growth, and differentiation of CD8 T cells, enhancing their ability to kill infected cells.
Why is the skin considered a potent barrier against microbes?
Because it is dry, oily, and salty, making it difficult for most microbes to get past.
What is the mucociliary escalator and its function?
The mucociliary escalator of the throat moves mucus up the throat where anything contained in it can be swallowed and destroyed in the stomach.
How do lymphocyte receptors achieve signal transduction?
Accessory proteins take care of signal transduction.
What is an example of a sequence read in different reading frames?
The sequence 'NOWITSNOTTOOHOTFORZOOYOUCANSEESIXOWLFLY' can be read in different frames: 'NOW ITS NOT TOO HOT FOR ZOO YOU CAN SEE SIX OWL FLY', 'N OWI TSN OTT OOH OTF ORZ OOY OUC ANS EES IXO WLF LY', and 'NO WIT SNO TTO OHO TFO RZO OYO UCA NSE ESI XOW LFL Y'.
How do macrophages contribute to the immune response?
Macrophages contribute to the immune response by presenting antigens to T cells and secreting cytokines that modulate the activity of other immune cells.
What percentage of the population is infected with Cytomegalovirus (CMV)?
40% to 70% are infected with CMV.
What contributes to sequence diversity in combinatorial diversity?
Tdt (Terminal deoxynucleotidyl transferase).
What are the two possible fates of lymphocytes during their maturation cycle?
Lymphocytes are either activated or killed.
Why is antigen presentation important for T cell activation?
Antigen presentation is crucial for T cells to recognize and respond to pathogens.
What is the role of effector T cells?
Effector T cells perform functions such as killing infected cells (cytotoxic T cells) or helping other immune cells (helper T cells).
What is clonal selection in the context of B and T cells?
Clonal selection is the process by which specific B and T cells are activated and proliferate in response to recognizing an antigen.
What are normal microbiota?
Microorganisms found growing on body surfaces of healthy individuals.
Why are dendritic cells considered the most important Antigen Presenting Cell (APC)?
Because they are the key messengers that can present antigens to the adaptive immune response and also phagocytose.
What is the primary function of Th1 cells?
Th1 cells are involved in cell-mediated immunity and help activate macrophages.
Which cells are involved in the cell-mediated response?
T cells.
Where is the Fab fragment located on an antibody?
At the tip of the 'Y'.
What do NK cells release upon activation?
NK cells release Interferon-gamma (IFN-γ).
How does the adaptive response compare to the first response in terms of speed and strength?
The adaptive response is usually faster and stronger than the first response.
What are the results of T cell activation?
Stimulation of both innate and adaptive responses, cytokine production and release, inflammation, CTL activity, and B cell regulation
What would happen if dendritic cells die off?
There would be no adaptive immune response.
What molecules do CTLs release to induce apoptosis in target cells?
Perforin and granzymes.
Where is the Fc fragment located on an antibody?
At the base of the 'Y'.
What role does the Fas-FasL interaction play in CTL function?
It triggers apoptosis in the target cell.
What is the primary function of TH1 cells?
TH1 cells are primarily involved in cell-mediated immunity and help activate macrophages.
Do Natural Killer (NK) cells have antigen specificity?
No, they lack antigen specificity.
What is the process of T cell activation?
T cells are activated when their TCRs bind to an antigen-MHC complex, along with co-stimulatory signals from antigen-presenting cells.
How do T cells recognize antigens?
T cells recognize antigens that have been processed and presented by another cell.
How is the VDJ segment linked to the closest C segment?
By alternative splicing at the RNA level.
What segments do the light-chain (BCR) and α-chain (TCR) have?
V and J segments.
What type of receptor is the macrophage mannose receptor and what does it bind?
The macrophage mannose receptor is a C-type lectin that binds sugar residues.
Why are NK cells important in viral infections?
Because they recognize and destroy host cells that lack MHC class I molecules, which is a common occurrence in viral infections.
What types of antigens can B cells recognize?
B cells can recognize a wide variety of antigens, including proteins, polysaccharides, lipids, and nucleic acids.
What are monocytes and where do they circulate?
Monocytes are a type of white blood cell that circulates in the blood.
What is the nature of MHC class II genes in terms of inheritance?
They are inherited as pairs of α- and β-chain genes from each parent.
What are the primary types of adaptive immune cells?
The primary types of adaptive immune cells are T cells and B cells.
What is the primary function of IL-2?
IL-2 primarily stimulates the growth and differentiation of T cells.
What does allelic exclusion ensure in lymphocytes?
It ensures that each lymphocyte will only express one antigen-specific receptor.
What type of antigens are presented by MHC class I molecules?
Endogenous antigens.
Which cells are known for cross-promotion of antigens?
Dendritic cells, B cells, and macrophages.
What types of cells do activated T cells differentiate into?
Activated T cells differentiate into effector T cells and memory T cells.
How many lymphocytes do we have in our bodies?
Billions.
Which cells are primarily involved in the intracellular response of adaptive immunity?
T cells.
What is the primary function of the T Cell Receptor (TCR)?
The primary function of the T Cell Receptor (TCR) is to recognize and bind to specific antigens presented by Major Histocompatibility Complex (MHC) molecules on the surface of antigen-presenting cells.
What are the main subsets of Helper T Cells?
Th1, Th2, Th17, and Treg cells.
Can any effector cell migrate to the site of infection?
Yes, any effector cell can migrate to the site of infection, but there is selective retention.
What is the primary function of cell-mediated immunity?
To defend against intracellular pathogens and cancer cells.
What happens to T cells after they pass positive and negative selection?
They become single-positive T cells, expressing either CD4 or CD8, and are almost fully mature.
How do T cells recognize antigens?
By the T cell receptor (TCR).
What does the Fc fragment of an antibody consist of?
Only the heavy chain constant region.
What is the role of sphingosine 1-phosphate (S1P) in T cell migration?
S1P is high in blood and lymph and low in lymph tissue, influencing T cell movement.
What are Helper T cells?
Helper T cells are a type of T cell that play an important role in the immune system by releasing cytokines to regulate immune responses.
How does the immunological synapse contribute to T cell activation?
The immunological synapse allows for the stable interaction and signaling between the T cell receptor (TCR) and the antigen-MHC complex, along with co-stimulatory signals, which are crucial for T cell activation.
What is the role of sebum secreted by sebaceous (oil) glands?
Sebum helps keep the skin pliable and lowers skin pH to a level inhibitory to many bacteria.
Which antibody isotype is the most abundant in serum and provides the majority of antibody-based immunity against pathogens?
IgG.
What is the significance of the reading frame in protein synthesis?
The reading frame determines which amino acids will be encoded by the nucleotides, thus affecting the resulting protein.
What is chemotaxis in the context of cell migration?
Chemotaxis is the directed movement of cells towards higher concentrations of a chemical signal, often seen in immune cell migration towards infection sites.
Can T cell exhaustion be reversed?
In some cases, T cell exhaustion can be partially reversed by blocking inhibitory receptors like PD-1 and CTLA-4, which can restore some T cell function.
What initiates inflammation?
Microbial invasion or tissue damage.
How do Helper T cell cytokines influence B cells?
Helper T cell cytokines, such as IL-4, promote B cell proliferation and differentiation into plasma cells that produce antibodies.
Which cytokine is predominantly produced by TH1 cells?
TH1 cells predominantly produce the cytokine IFN-γ (Interferon gamma).
Why is fever considered an important host defense mechanism?
Because it inhibits the growth of pathogens and activates other body defenses.
What type of immune response is TH1 associated with?
TH1 is associated with the cell-mediated immune response.
What is the predominant type of T cell in older individuals?
In older individuals, the bulk of T cells are memory T cells.
What are cytokines?
Cytokines are small proteins that are important in cell signaling, especially in immune responses.
Which molecules are not expressed by effector T cells?
L-selectin and CCR7.
What is the structure of MHC molecules in terms of chains?
MHC molecules have two chains, typically referred to as chain A and chain B.
What is the function of cytokines in cell-mediated immunity?
Cytokines are signaling molecules that mediate and regulate immunity, inflammation, and hematopoiesis.
What is the primary function of dendritic cells?
They are involved in antigen presentation to the adaptive immune response.
What is the second signal required for CTL activation?
Co-stimulatory signals provided by interactions between CD28 on the CTL and B7 on the antigen-presenting cell.
What do lymphocytes recognize and bind to?
Antigen.
What is the role of Tumor Necrosis Factor-alpha (TNF-α) in innate immunity?
TNF-α is involved in systemic inflammation and can induce fever and apoptosis.
How do T Cell Receptors (TCRs) recognize antigens?
T Cell Receptors (TCRs) recognize antigens by binding to peptide fragments presented by Major Histocompatibility Complex (MHC) molecules on the surface of antigen-presenting cells.
Which cells are primarily responsible for providing the necessary cytokines for CTL activation?
Helper T cells (Th cells).
Which cells are primarily involved in cell-mediated immunity?
T cells, including cytotoxic T cells (CD8+) and helper T cells (CD4+).
What role does the Golgi apparatus play in antigen presentation?
It ships proteins processed in the endoplasmic reticulum (ER) to their destination.
Where do monocytes originate?
Monocytes originate in the bone marrow.
What is the role of cytokines in cell-mediated immunity?
Cytokines are signaling molecules that help regulate and coordinate the immune response.
What is a reading frame in the context of genetic sequences?
A reading frame is a way of dividing the sequence of nucleotides in a nucleic acid (DNA or RNA) into a set of consecutive, non-overlapping triplets or codons.
How do effector proteins function in signal transduction?
Effector proteins carry out the cellular response to the signal, such as altering gene expression or modifying cellular metabolism.
What provides the first signal in the two-signal requirement for lymphocyte activation?
The first signal is provided by the recognition of an antigen by the lymphocyte receptor.
How does T cell exhaustion impact immune response?
T cell exhaustion leads to a diminished immune response, making it difficult for the body to effectively combat chronic infections or cancer.
What principle behind vaccines is related to the adaptive immune response?
Vaccines work on the principle that the adaptive response becomes faster and stronger with subsequent exposures.
What happens to S1P receptor expression if a T cell recognizes an antigen?
If the antigen is recognized, S1P receptor expression is suppressed for several days.
Why is the two-signal requirement important for lymphocyte activation?
The two-signal requirement ensures that lymphocytes are only activated in the presence of a genuine threat, preventing inappropriate immune responses.
Where are B-2 cells primarily located?
In the lymph nodes.
What is the significance of G-protein coupled receptors (GPCRs) in signal transduction?
GPCRs are a large family of receptors that play a key role in many signal transduction pathways by activating G-proteins.
What are the four cardinal signs of inflammation?
Heat, pain, redness, swelling.
What is the first signal required for T cell activation?
The first signal is the recognition of the antigen-MHC complex by the T cell receptor (TCR).
What do scavenger receptors recognize?
Scavenger receptors recognize anionic polymers and acetylated low-density lipoproteins.
What role does the invariant chain (Ii) play in the MHC Class II pathway?
It prevents premature binding of peptides to MHC Class II molecules and directs them to the endosomal/lysosomal pathway.
What do Toll-like receptors bind?
Toll-like receptors bind a variety of membrane or vesicle-associated microbial antigens.
What role do cytotoxic T-lymphocytes play in cell-mediated immunity?
Cytotoxic T-lymphocytes directly kill infected cells by recognizing antigens presented on their surface.
How does V(D)J recombination contribute to the immune response?
By creating a diverse repertoire of antibodies, V(D)J recombination enables the immune system to recognize and respond to a vast array of pathogens.
What is the primary function of cell-mediated immunity?
To defend against intracellular pathogens and cancer cells.
What is unique about each B cell in our bodies?
Each B cell recognizes something completely different from all of the others.
Which receptors are subject to allelic exclusion?
TCR (T Cell Receptor) and BCR (B Cell Receptor).
How do cytotoxic T cells (CD8+) kill infected cells?
By recognizing antigens presented by MHC class I molecules and inducing apoptosis in the infected cells.
How do effector cells recognize microbial antigens?
Effector cells recognize microbial antigens through MHC-associated antigen presentation.
What is T cell exhaustion?
T cell exhaustion is a state of dysfunction that arises in T cells during chronic infections or cancer, characterized by poor effector function, sustained expression of inhibitory receptors, and a transcriptional state distinct from functional effector or memory T cells.
What is the role of Interleukin-6 (IL-6) in innate immunity?
IL-6 stimulates acute phase responses and the production of antibodies.
What is the significance of MHC class I molecules in cell-mediated immunity?
They present intracellular antigens to cytotoxic T cells, triggering an immune response.
How do cytotoxic T cells (CD8+) kill infected cells?
By recognizing antigens presented by MHC class I molecules and inducing apoptosis in the infected cells.
What are the key components of an immunological synapse?
Key components include the T cell receptor (TCR), major histocompatibility complex (MHC) molecules, co-stimulatory molecules, and adhesion molecules.
What role do helper T cells (CD4+) play in cell-mediated immunity?
They assist other immune cells by releasing cytokines that enhance the immune response.
What are lymphocyte receptors?
Protein receptors displayed on the surface of the cell.
What is produced and released as a result of T cell activation?
Cytokines
What provides the second signal in the two-signal requirement for lymphocyte activation?
The second signal is provided by co-stimulatory molecules on antigen-presenting cells.
What is the role of cytokines in cell-mediated immunity?
Cytokines are signaling molecules that help regulate and coordinate the immune response.
What is the general outcome of signal transduction?
The general outcome of signal transduction is a specific cellular response, such as gene expression, cell division, or apoptosis.
How do T cells recognize antigens?
Through their T cell receptors (TCRs) which bind to specific antigens presented by MHC molecules.
Which antibody isotype is present on the surface of immature B-lymphocytes and plays a role in initiating B-cell activation?
IgD.
What marker do B-1 cells express?
CD5.
What is the primary function of MHC Class II molecules?
To present antigens to helper T cells (CD4+ T cells).
What is the significance of memory cells in the secondary immune response?
Memory cells enable the immune system to respond more quickly and effectively upon re-exposure to the same antigen.
How many pairs of class II α- and β-chain genes do humans have?
Three pairs.
At what level does the V-J rearrangement occur?
At the DNA level.
What are adaptive cells?
Adaptive cells are immune cells that are part of the adaptive immune system, primarily including T cells and B cells.
What is the primary function of cytokines?
Cytokines bind to surface receptors and regulate cell function.
What is the primary function of Helper T Cells?
Helper T Cells assist other white blood cells in immunologic processes, including the activation of B cells to secrete antibodies and macrophages to destroy ingested microbes.
Where do the recruited cells go after entering the tissue during an acute inflammatory response?
They move towards the site of infection to combat the bacteria.
Where do B and T cells reside?
B and T cells reside in the lymph nodes.
What are the main components involved in signal transduction pathways?
Receptors, ligands, second messengers, and effector proteins.
What is the role of MHC (Major Histocompatibility Complex) in the immune system?
MHC molecules present peptide fragments to T cells, enabling the immune system to recognize and respond to pathogens.
What is the primary function of dendritic cells?
To act as antigen-presenting cells that initiate and modulate the immune response.
What is required for full T cell activation besides TCR engagement?
Co-stimulation
What is the difference between alpha-beta (αβ) TCRs and gamma-delta (γδ) TCRs?
Alpha-beta (αβ) TCRs are more common and primarily recognize peptide antigens presented by MHC molecules, while gamma-delta (γδ) TCRs can recognize a broader range of antigens, including non-peptide antigens, and are less dependent on MHC presentation.
What are second messengers in signal transduction?
Second messengers are intracellular signaling molecules released by the cell in response to exposure to extracellular signaling molecules.
What are the primary roles of CD4 and CD8 T cells in the immune response?
CD4 T cells, also known as helper T cells, assist other cells in the immune response, while CD8 T cells, also known as cytotoxic T cells, directly kill infected or cancerous cells.
What are the major isotypes (classes) of antibodies?
IgG, IgA, IgM, IgE, and IgD.
How long does the adaptive response typically take compared to the normal 7-10 days?
It could take just 2-3 days and even faster the next time.
What is the environment inside endocytic vesicles and what is its function?
They have low pH and proteases that break down protein.
What occurs if a T cell does not recognize an antigen in the lymph tissue?
If the antigen is not recognized, S1P receptor expression increases, allowing the T cell to leave through the efferent lymph vessel.
What is the role of phosphorylation in signal transduction?
Phosphorylation is a common mechanism for activating or deactivating proteins and enzymes in signal transduction pathways.
What is the relationship between MHC molecules and antigens?
MHC molecules are always in excess to antigens.
What happens if the reading frame is shifted?
A shift in the reading frame, known as a frameshift mutation, can result in a completely different translation from the original, often leading to nonfunctional proteins.
Why do NK cells kill certain cells?
NK cells kill cells that show signs of being abnormal or infected.
What is another name for B-2 cells?
Follicular B cells.
What are the key events that occur during inflammation?
Dilation of blood vessels, leakage of fluid from vessels, and migration of leukocytes and phagocytes.
What are the two anatomical barriers mentioned?
Skin and mucus.
How many class I α-chain genes do humans have?
Three.
How do cells prevent MHC Class I antigens from binding to MHC Class II molecules?
By using the invariant chain (Ii) which blocks the peptide-binding groove of MHC Class II molecules in the endoplasmic reticulum.
How do classic childhood rashes typically enter the body?
They typically enter by the lungs, not by direct skin contact.
What is the state of Marginal zone B cells?
Resting mature B cells.
What is the inflammasome?
The inflammasome is a multiprotein complex in the cytosol that activates inflammatory responses.
How does fever affect other body defenses?
It activates and speeds them up.
Where do naïve T cells migrate?
Between blood and lymph tissue.
What is often the end result of signal transduction?
Altered gene expression.
What are the two main types of immune responses?
Innate and Adaptive.
What is the role of primary (generative) lymphoid organs?
They are where B and T cells develop.
What type of molecules do T cells recognize?
T cells only recognize proteins.
How do TH1 cells contribute to the activation of macrophages?
TH1 cells secrete IFN-γ, which activates macrophages to enhance their microbicidal activity.
What are Damage Associated Molecular Patterns (DAMPs)?
Signals of tissue damage recognized by the innate immune response.
Which cells are primarily involved in cell-mediated immunity?
T cells, including cytotoxic T cells (CD8+) and helper T cells (CD4+).
How many MHC class I genes do you inherit from each parent?
Three from each parent, totaling six.
How do NK cells complement the function of cytotoxic T cells?
They pick up the slack for cytotoxic T cells by targeting and destroying cells that cytotoxic T cells might miss.
What is the primary function of the inflammasome?
To activate inflammatory responses by processing pro-inflammatory cytokines like IL-1β and IL-18.
What is the significance of the MHC gene combinations in siblings?
Siblings can have different combinations of MHC genes, leading to potential mismatches.
What is the function of CD28 in T cell activation?
CD28 provides a costimulatory signal necessary for full T cell activation by binding to B7 on the antigen-presenting cell.
What is the outcome of successful T cell activation?
Successful T cell activation leads to T cell proliferation, differentiation into effector cells, and the initiation of an adaptive immune response.
What are the two 'arms' of the immune system?
Innate Response and Adaptive Response.
How can the immune system's failure to respond properly affect cancer?
It may not pick up and destroy cancer cells.
What is another name for white blood cells (WBC)?
Leukocytes.
What is the primary role of white blood cells (WBC)?
They are important in host defenses.
Where are defensins found?
On mucous membranes and in phagocytes.
What is the purpose of inflammation in innate immunity?
To localize and eliminate pathogens and to remove damaged tissue.
How do B cells contribute to adaptive immunity?
B cells produce antibodies that neutralize pathogens and mark them for destruction.
What is the seventh letter of the Greek alphabet?
Eta (Η, η)
What is the fifteenth letter of the Greek alphabet?
Omicron (Ο, ο)
Where are the Hypervariable Regions (HV) or Complementarity Determining Regions (CDR) found?
On the loops at the tips of the variable region.
What is the role of secondary (peripheral) lymphoid organs?
They are sites where immune cells encounter antigens and initiate immune responses.
What are ligands?
Molecules that bind to receptors on the cell surface or inside the cell.
What is the role of IL-12 in the TH1 response?
IL-12 is crucial for the differentiation of naive T cells into TH1 cells.
What is the role of the external domain of a receptor?
The external domain binds the ligand.
What is the typical time frame for the contraction phase in an immune response?
The contraction phase typically occurs around Day 30.
How does fever inhibit the growth of pathogens?
By elevating the body temperature above the maximum growth temperature of pathogens.
What role do cytokines play in T cell activation?
Cytokines provide additional signals that promote T cell proliferation, differentiation, and survival.
Which types of molecules induce a strong immune response?
Proteins and polysaccharides.
Where can lysozyme be found?
In tears, saliva, blood, and phagocytes.
What is the most abundant phagocyte in the innate immune response?
Neutrophils.
What happens during transplant rejection?
The immune system treats the transplant as foreign if it is not identical.
What is the primary function of red blood cells (RBC)?
To carry oxygen in the blood.
What are the two main subsets of Helper T Cells?
Th1 and Th2 cells
What happens when the first line barriers of the immune system are breached?
Recognition by tissue macrophages and complement.
What is the majority of pus composed of?
Dead neutrophils.
What are sensor systems in innate immunity?
Mechanisms like pattern recognition receptors (PRRs) that detect pathogen-associated molecular patterns (PAMPs).
What is the role of phagocytosis in innate immunity?
The process by which phagocytes engulf and digest pathogens and debris.
How do natural killer (NK) cells contribute to effector functions?
NK cells kill virus-infected cells and tumor cells by releasing cytotoxic granules.
What role do cytokines play in the immune system?
Cytokines are signaling molecules that mediate and regulate immunity, inflammation, and hematopoiesis.
What happens when all three complement pathways converge?
They produce a specific molecule and the same set of effector proteins.
How do T cells contribute to adaptive immunity?
T cells help in killing infected host cells, activating other immune cells, and regulating immune responses.
How do CD8+ T cells induce apoptosis in target cells?
CD8+ T cells induce apoptosis through the release of perforin and granzymes or by engaging death receptors on the target cell surface.
What is the ninth letter of the Greek alphabet?
Iota (Ι, ι)
What is the nineteenth letter of the Greek alphabet?
Tau (Τ, τ)
How do NK cells augment the adaptive immune response?
They are important in the process of antibody-dependent cellular toxicity, enabling the killing of host cells with foreign protein in the membrane.
Which pathogens are typically targeted by the TH1 response?
TH1 responses typically target intracellular pathogens such as viruses and certain bacteria.
Where are B-1 cells mainly found?
In the peritoneal and pleural cavity fluid.
What is the standard innate response to inflammation?
Increased blood flow to the area.
What is the sequence of rearrangement for light-chain (BCR) and α-chain (TCR)?
V-J rearrangement.
What can happen if a large area of inflammation is not confined?
It can be damaging and form an abscess.
What factors influence immunogenicity?
Foreignness, size, and complexity of the compound.
How is the VJ segment linked to the C segment?
By alternative splicing at the RNA level.
What happens to the invariant chain (Ii) once MHC Class II molecules reach the endosomal/lysosomal compartments?
The invariant chain is degraded, allowing antigenic peptides to bind to the MHC Class II molecules.
What molecules do naïve T cells express to mediate migration into lymph nodes?
L-selectin and chemokine receptor CCR7.
What does peroxidase do?
Peroxidase breaks down hydrogen peroxide to produce reactive oxygen.
What are neutrophils sometimes called?
Polymorphonuclear neutrophilic leukocytes (PMNs).
How does the number of epitopes on an antigen affect the immune response?
More epitopes generally lead to a better immune response.
What are the first line anatomical barriers in innate immunity?
Physical barriers such as skin and mucous membranes that prevent pathogen entry.
What is a naïve immune cell?
A naïve immune cell is one that has not yet encountered its specific antigen.
What is an effector immune cell?
An effector immune cell is one that has been activated and is actively responding to an antigen.
Does the innate immune response have memory?
No, the innate immune response does not have memory.
What happens when NK cells encounter cells with low or absent MHC class I molecules?
NK cells are more likely to kill cells with low or absent MHC class I molecules, as the inhibitory signals are reduced.
How many different ways can the complement system be activated?
Three different ways.
What are the three pathways of complement activation?
Lectin pathway, classical pathway, and alternative pathway.
What is the function of Th2 cells?
Th2 cells produce cytokines such as IL-4 and IL-5 that stimulate B cell differentiation and antibody production, particularly IgE, and are involved in responses to extracellular parasites.
What is the eighteenth letter of the Greek alphabet?
Sigma (Σ, σ/ς)
What is the function of mannose-binding lectin in the immune system?
Mannose-binding lectin is free in plasma, part of the collectin family, and binds sugar residues.
What type of host cells do NK cells recognize and destroy?
Host cells with no MHC class I surface molecules.
What antigens select B-1 cells?
Ubiquitous self and foreign antigens.
What is the second signal required for T cell activation?
The second signal is the costimulatory signal provided by the interaction between CD28 on the T cell and B7 on the antigen-presenting cell (APC).
What is another name for NK cells?
Large granular lymphocytes.
How do cytotoxic T cells (CD8+) kill infected cells?
By recognizing antigens presented by MHC class I molecules and inducing apoptosis in the infected cells.
What role do helper T cells (CD4+) play in cell-mediated immunity?
They assist other immune cells by releasing cytokines that enhance the immune response.
What type of antibodies do B-1 cells make against the wrong blood type?
IgM.
What do RIG-I-like helicases (RLH) sense?
RIG-I-like helicases (RLH) sense cytoplasmic viral RNAs.
What is the role of high endothelial venules (HEV) in naïve T cell migration?
HEV endothelial cells have the ligand for L-selectin, facilitating T cell migration into lymph nodes.
Why is the MHC Class I pathway important?
The MHC Class I pathway is important because it allows the immune system to monitor and respond to intracellular infections and malignancies by presenting endogenous antigens to CD8+ cytotoxic T cells.
How do interferons contribute to the immune response?
Interferons are important in the control of viral infections and the inflammatory response.
What is the role of interleukins in the immune system?
Interleukins are produced by leukocytes and play a role in both innate and adaptive immunity.
Which granulocytes are active in allergic reactions?
Basophils, Eosinophils, and Mast cells.
What role do cytotoxic T lymphocytes (CTLs) play in effector functions?
CTLs kill infected cells by inducing apoptosis through the release of perforin and granzymes.
Where are neutrophils found?
In the blood.
Where are mast cells typically found?
In tissues.
How do Helper T Cells contribute to the immune response against intracellular pathogens?
Helper T Cells, particularly Th1 cells, activate macrophages and cytotoxic T cells to destroy cells infected with intracellular pathogens.
How do Helper T Cells contribute to the immune response against extracellular pathogens?
Helper T Cells, particularly Th2 cells, activate B cells to produce antibodies that neutralize extracellular pathogens.
What happens if a pathogen is detected in tissue?
A macrophage will take care of it.
What triggers each of the three complement pathways?
Lectin pathway is triggered by lectin binding to pathogens, classical pathway by antigen-antibody complexes, and alternative pathway by pathogen surfaces.
How do Th17 cells contribute to the immune response?
Th17 cells produce IL-17 and other cytokines that recruit neutrophils and are important in defense against extracellular bacteria and fungi.
What is the twentieth letter of the Greek alphabet?
Upsilon (Υ, υ)
What characterizes the secondary immune response?
The secondary immune response occurs upon subsequent exposure to the same antigen, leading to a faster and more robust response due to memory cells.
What are endogenous pyrogens?
Fever-inducing cytokines produced by the body.
Do B cells require antigens to be processed by another cell for recognition?
No, B cells can recognize antigens directly without the need for processing by another cell.
What are exogenous pyrogens?
Fever-inducing substances from microbial products.
What happens if a T cell receives only the first signal without the second signal?
The T cell becomes anergic, meaning it is functionally inactivated and unable to respond to the antigen.
What is the source of the antigen in the MHC Class I pathway?
The source of the antigen in the MHC Class I pathway is endogenous, meaning it originates from within the cell, typically from intracellular pathogens like viruses or from the cell's own proteins.
What deficiency characterizes Leukocyte Adhesion Deficiency?
Deficiency in cell adhesion molecules.
What is unique about the MHC Class I pathway?
The MHC Class I pathway presents endogenous antigens to CD8+ cytotoxic T cells. This pathway is crucial for the immune system to detect and destroy infected or cancerous cells.
How do temperature and pH affect microbial growth?
They determine microbial growth by influencing protein folding and other cellular processes.
Which molecule is primarily expressed on the surface of Helper T Cells?
CD4
What does a complete mismatch in MHC genes between siblings imply?
It implies that the siblings have entirely different sets of MHC genes.
What are some effects of triggering receptors in the immune response?
Triggering receptors can increase phagocytosis, increase proinflammatory cytokine production, and increase the production of co-stimulatory molecules.
Which complement components are associated with both autoimmune disorders and recurrent bacterial infections?
C1r, C2, C5, C7.
What are the primary components of the innate immune system?
Physical barriers, phagocytic cells, natural killer cells, and various proteins like complement.
What was IL-6 originally discovered to do?
IL-6 was originally discovered to repress tumors.
What are the four categories of white blood cells (WBC)?
Granulocytes, Mononuclear Phagocytes, Dendritic cells, Lymphocytes.
What is the significance of the complement system in effector functions?
The complement system enhances the ability of antibodies and phagocytic cells to clear pathogens and damaged cells.
Why are both the innate and adaptive immune responses necessary?
Both are needed to effectively combat infections; the innate response provides immediate defense, while the adaptive response provides specific and long-lasting immunity.
What is the outcome of the complement cascade?
The cascade amplifies along the way, leading to the production of effector proteins.
What are the primary effector functions of CD8+ T cells?
CD8+ T cells primarily function to kill infected or cancerous cells by inducing apoptosis.
What is the fourteenth letter of the Greek alphabet?
Xi (Ξ, ξ)
What components make up a fully functioning lymphocyte receptor?
The main receptor and accessory proteins.
What does positive selection in T cells relate to?
The receptor’s ability to recognize MHC.
What is the primary function of cell-mediated immunity?
To defend against intracellular pathogens and cancer cells.
What is the mononuclear phagocyte system?
A collection of phagocytic cells, previously called the reticuloendothelial system.
Does the principle of CDRs apply to antibodies as well?
Yes, the same principle applies to antibodies.
What can an overly aggressive immune response lead to?
Tissue and nerve damage, especially due to inflammation.
How do macrophages originate and where are they abundant?
Macrophages differentiate from monocytes and are abundant in the liver, spleen, lymph nodes, lungs, and peritoneal cavity.
What is the result of Interleukin Receptor-Associated Kinase Deficiency?
Lack of response to TLR and IL-1.
What are the general categories of blood cells?
Red blood cells (RBC), Platelets, White blood cells (WBC).
How do macrophages react to tissue damage and signs of invasion?
Macrophages react to tissue damage and signs of invasion by initiating the innate immune response.
How do cytosolic DNA sensors contribute to the immune response?
They detect foreign or damaged DNA in the cytoplasm and activate signaling pathways like the STING pathway to initiate an immune response.
What mechanisms draw naïve T cells to the lymph node?
The expression of L-selectin, CCR7, and the function of Sphingosine 1-phosphate.
Which cells are primarily responsible for cell-mediated effector functions?
T cells, particularly cytotoxic T lymphocytes (CTLs) and helper T cells.
How does normal flora contribute to innate immunity?
By competing with pathogens for nutrients and space, thereby preventing their colonization.
What is required for immune cell activation?
No activation without costimulation.
What role do inhibitory receptors play in NK cell function?
Inhibitory receptors on NK cells recognize MHC class I molecules on healthy cells, preventing the NK cells from killing them.
What type of enzymes are several complement proteins?
Proteases that are active upon proteolytic cleavage.
How does the innate immune system recognize pathogens?
Through pattern recognition receptors (PRRs) that detect pathogen-associated molecular patterns (PAMPs).
What are the outcomes of complement activation?
Opsonization, inflammation, and cell lysis.
What is the tenth letter of the Greek alphabet?
Kappa (Κ, κ)
What is the twenty-first letter of the Greek alphabet?
Phi (Φ, φ)
What is the role of IL-10 produced by Helper T cells?
IL-10 is an anti-inflammatory cytokine produced by Helper T cells that helps to limit immune responses and prevent tissue damage.
What is an antigen?
A compound that elicits an immune response.
What does negative selection in T cells focus on?
The antigen being presented.
Where do Marginal zone B cells reside?
In the marginal sinus of the spleen.
What is the function of the transcription factor AIRE?
AIRE (autoimmune regulator) is involved in the negative selection of T cells.
Where are MHC Class II molecules loaded with antigens?
In the endosomal/lysosomal compartments after the invariant chain is degraded.
What would happen if there was a defect in HLA-DM?
There would be no MHC II because of the lack of presentation of CLIP.
What are granulocytes?
Granulocytes are a type of white blood cell that contain cytoplasmic granules.
What is the role of cytokines in cell-mediated immunity?
Cytokines are signaling molecules that regulate the intensity and duration of the immune response.
What is the STING pathway?
The STING pathway is a signaling pathway activated by cytosolic DNA sensors that leads to the production of type I interferons and other cytokines.
What is the process of clonal expansion in cell-mediated immunity?
It is the proliferation of T cells after recognizing an antigen, leading to a large number of effector T cells.
What happens when chemokines bind to CCR7 on naïve T cells?
The T cell makes the integrin LFA-1, which binds tightly to ICAM-1.
What are effector functions in the context of adaptive immune cells?
Effector functions refer to the actions performed by activated T cells and B cells to eliminate pathogens, such as cytotoxic activity by T cells and antibody production by B cells.
What is the function of tumor necrosis factor (TNF)?
Tumor necrosis factor kills tumor cells and initiates inflammation.
How do cells follow chemokines?
Cells follow a concentration gradient of chemokines.
How do NK cells identify cells to target?
NK cells identify target cells through a balance of activating and inhibitory signals received from receptors on their surface.
Which cytokines are primarily produced by Th2 cells?
Interleukin-4 (IL-4), Interleukin-5 (IL-5), and Interleukin-13 (IL-13)
What are some examples of activating receptors on NK cells?
Examples of activating receptors on NK cells include NKG2D and natural cytotoxicity receptors (NCRs).
How do macrophages participate in effector functions?
Macrophages phagocytose pathogens and present antigens to T cells, and they can also be activated by cytokines to enhance their microbicidal activity.
What is the role of the complement system in the immune response?
It acts as a blood-based alarm system.
What is the fourth letter of the Greek alphabet?
Delta (Δ, δ)
What is the thirteenth letter of the Greek alphabet?
Nu (Ν, ν)
How many Complementarity Determining Regions (CDRs) are there in each of the Vα and Vβ domains?
There are 3 CDRs in each of the Vα and Vβ domains.
What additional properties does mucus have besides being a physical barrier?
Mucus has some antimicrobials that trap and protect against pathogens.
How many CDRs interact with the antigen in total?
A total of 6 CDRs interact with the antigen.
What is the cause of Chronic Granulomatous Disease?
Lack of NADPH Oxidase.
What is the role of the cytoplasmic domain of a receptor?
The cytoplasmic domain transmits the signal inside the cell.
How do Marginal zone B cells respond to antigens?
They have a quick response to common environmental and self antigens in the bloodstream.
What are NOD-like receptors and what do they sense?
NOD-like receptors are intracellular sensors for microbial products.
Which rearrangement happens first, D-J or V-DJ?
D-J rearrangement happens first.
What is the main function of T cells in the adaptive immune system?
T cells primarily function in cell-mediated immunity, identifying and destroying infected cells.
What is another name for red blood cells (RBC)?
Erythrocytes.
What is the difference between primary and secondary immune responses?
Primary response occurs on first exposure to an antigen, while secondary response is faster and stronger upon subsequent exposures.
What is the primary function of the immune system?
To protect the body against pathogens and foreign substances.
What are platelets and what is their function?
Platelets are fragments of megakaryocytes and are an important component in blood clotting.
What are NK cells?
Natural Killer (NK) cells are a type of lymphocyte that play a crucial role in the innate immune response.
What is the role of Th2 cells?
Th2 cells are involved in humoral immunity and help activate B cells to produce antibodies.
What effect do macrophage-produced cytokines have on other cells?
They cause other cells to produce cytokines and epithelial cells to express E and P selectins and ICAMs.
Which cells are primarily involved in innate immunity?
Phagocytes (such as macrophages and neutrophils), natural killer cells, and dendritic cells.
What are ICAMs and what do they bind to?
ICAMs are expressed by epithelial cells and they bind to integrins.
What is the significance of the balance between activating and inhibitory signals in NK cell function?
The balance between activating and inhibitory signals ensures that NK cells can effectively target and kill abnormal cells while sparing healthy cells.
What is the role of memory cells in adaptive immunity?
Memory cells remember past infections and provide a faster and stronger response upon re-exposure to the same pathogen.
How do T follicular helper (Tfh) cells assist in the immune response?
T follicular helper (Tfh) cells help B cells in the germinal centers of lymph nodes to produce high-affinity antibodies and undergo class switching.
What are the two main functions of the innate immune response in dealing with pathogens?
Direct destruction of pathogens and serving as a communication link with the adaptive response.
What is signal transduction?
A cascade of events that starts when a receptor binds a ligand and transmits a signal inside the cell.
What is the role of the T cell receptor (TCR) in T cell activation?
The TCR recognizes and binds to the antigen-MHC complex on the surface of the antigen-presenting cell.
What type of peptides are important for the MHC Class I pathway?
Peptides that are 8-10 amino acids long are important for the MHC Class I pathway. These peptides fit snugly into the binding groove of the MHC Class I molecule.
Can receptors be a single protein or a multi-protein complex?
Yes, receptors can be either a single protein or a multi-protein complex.
Which complement components are associated with recurrent bacterial infections?
C3, C6, Factor I.
What is immunodeficiency?
Not responding when it should, which can be primary or secondary.
What are effector functions in the immune system?
Effector functions are the mechanisms through which immune cells and molecules eliminate pathogens.
What are antimicrobial substances in the context of innate immunity?
Chemicals such as lysozyme, defensins, and complement proteins that inhibit or kill pathogens.
What is the primary characteristic of innate immunity?
Innate immunity provides immediate, non-specific defense against pathogens.
How do helper T cells contribute to effector functions?
Helper T cells secrete cytokines that activate other immune cells, such as macrophages and B cells.
Where are most complement proteins produced?
In the liver.
Which cells are primarily involved in adaptive immunity?
B cells and T cells.
What should you learn to love in immunology?
Lower-case Greek letters.
Can the adaptive immune response function without the innate immune response?
No, the adaptive immune response cannot function without the innate immune response.
What is the first letter of the Greek alphabet?
Alpha (Α, α)
What is the twenty-second letter of the Greek alphabet?
Chi (Χ, χ)
What is hypersensitivity in the context of immune response?
Responding when it shouldn’t.
What role do chemokines play in the immune system?
Chemokines are important in chemotaxis.
Which complement components are associated with autoimmune disorders like SLE and glomerulonephritis?
C1q, C1s, C4.
What is an epitope?
The chemical structure of a molecule that is directly recognized by the immune system.
What role do cells of the immune response play in innate immunity?
They are involved in recognizing and responding to pathogens.
What is the role of memory T cells in cell-mediated immunity?
They provide long-term immunity by quickly responding to previously encountered antigens.
What disorder is associated with a deficiency in C1INH?
Hereditary angioedema.
What distinguishes the adaptive immune response from the innate immune response?
The adaptive immune response is specific to particular pathogens and has memory, while the innate immune response is non-specific and immediate.
What are the main types of cells involved in the adaptive immune response?
B cells and T cells.
Into how many categories are white blood cells (WBC) divided?
Four categories.
What role do antibodies play in the immune system?
Antibodies bind to specific antigens to neutralize pathogens or mark them for destruction by other immune cells.
What is immunological memory?
The ability of the adaptive immune system to remember past encounters with pathogens and respond more rapidly and effectively upon subsequent exposures.
What is the fifth letter of the Greek alphabet?
Epsilon (Ε, ε)
What role do Th1 cells play in the immune response?
Th1 cells produce cytokines like IFN-γ that activate macrophages and promote cell-mediated immunity against intracellular pathogens.
What is the sixteenth letter of the Greek alphabet?
Pi (Π, π)
What are the specialized macrophages in the CNS, liver, lungs, and bones called?
Microglia in CNS, Kupffer cells in liver, alveolar macrophages in lungs, and osteoclasts in bones.
What is autoimmunity?
Responding to harmless antigens.
What are the main components of innate immunity?
Cells of the immune response, first line anatomical barriers, antimicrobial substances, normal flora, sensor systems, phagocytosis, inflammation, and fever.
Where is peroxidase found?
In saliva, body tissues, and phagocytes.
Which granulocytes are important in expelling parasitic worms?
Basophils, Eosinophils, and Mast cells.
What role does the STING pathway play in the immune system?
It helps in the production of type I interferons and other cytokines, which are crucial for antiviral and antibacterial defenses.
Where can lactoferrin be found?
In saliva, some phagocytes, blood, and tissue fluids.
What are defensins and what do they do?
Defensins are antimicrobial peptides that insert into microbial membranes.
Which cytokines are primarily produced by Th1 cells?
Interferon-gamma (IFN-γ) and Interleukin-2 (IL-2)
What are E and P selectins and what do they bind to?
E and P selectins are expressed by epithelial cells and they bind to sulfated-sialyl-Lewis X.
How does fever function as a component of innate immunity?
By raising the body's temperature to create an environment less favorable for pathogens and enhancing immune response.
What is the lectin pathway in the complement system?
A pathway that is part of the blood alarm system and requires lectin.
What is the third letter of the Greek alphabet?
Gamma (Γ, γ)
What are the main effector functions of CD4+ T helper cells?
CD4+ T helper cells assist other immune cells by secreting cytokines, enhancing the activity of macrophages, and aiding B cell antibody production.
What is the twelfth letter of the Greek alphabet?
Mu (Μ, μ)
What are cytosolic DNA sensors?
Cytosolic DNA sensors are proteins that detect the presence of DNA in the cytoplasm, which is usually a sign of infection or cellular damage.
What is the function of colony stimulating factors?
Colony stimulating factors are important in the multiplication and differentiation of leukocytes.
What are the two main types of immune responses?
Innate immune response and adaptive immune response.
How do Helper T Cells recognize antigens?
Helper T Cells recognize antigens presented by Major Histocompatibility Complex (MHC) class II molecules on the surface of antigen-presenting cells.
What is the role of lactoferrin?
Lactoferrin sequesters iron from microorganisms.
What are the two main types of immunity?
Innate immunity and adaptive immunity.
What is the role of tissue macrophages when the first line barriers are breached?
They recognize the breach and produce cytokines.
What is the complement system?
A collection of a large number of blood proteins, mostly produced by the liver.
What is the role of antibodies in effector functions?
Antibodies neutralize pathogens, opsonize them for phagocytosis, and activate the complement system.
What is the sixth letter of the Greek alphabet?
Zeta (Ζ, ζ)
What is the eleventh letter of the Greek alphabet?
Lambda (Λ, λ)
What is the twenty-fourth letter of the Greek alphabet?
Omega (Ω, ω)
What is the main function of B cells in the adaptive immune system?
B cells are responsible for producing antibodies that neutralize pathogens and mark them for destruction.
What are the two types of adaptive immunity?
Humoral and Cell-mediated immunity (CMI).
What are the characteristics of the innate immune response?
Non-specific, attacks a variety of pathogens, quick response, no memory.
What are the characteristics of the adaptive immune response?
Humoral and Cell-Mediated immunity, specific, recognizes specific pathogen molecules, slow initial response (7-10 days), immunological memory.
How does the innate immune response differ from the adaptive immune response in terms of speed?
The innate response is quick, while the adaptive response has a slow initial response (7-10 days).
How does the immune system recognize pathogens?
Through the detection of antigens, which are molecules found on the surface of pathogens.
What type of immunity is involved in the adaptive immune response?
Humoral and Cell-Mediated immunity.
Why is immunological memory important in the adaptive immune response?
It allows the immune system to recognize and respond more rapidly to pathogens it has encountered before.
What is antibody-dependent cellular cytotoxicity (ADCC)?
ADCC is a mechanism where immune cells, such as NK cells, recognize and kill antibody-coated target cells.
What is the eighth letter of the Greek alphabet?
Theta (Θ, θ)
What is the seventeenth letter of the Greek alphabet?
Rho (Ρ, ρ)