p.2
Peripheral Lymphoid Organs
What are the three parts of a lymph node?
Cortex, medulla, and paracortex.
p.9
Macrophages and Dendritic Cells
What role do macrophages play in adaptive immunity?
Macrophages act as antigen presenting cells (APCs) by capturing and processing antigens, then presenting them with MHC class II molecules to helper T cells.
p.5
Lymphoid Cells: T Cells, B Cells, and NK Cells
What are the two regions of the extracellular domain of each T cell receptor (TCR) polypeptide chain?
Variable and constant region.
p.3
Peripheral Lymphoid Organs
Where are Peyer's patches located?
In the submucosa of the intestinal wall.
What is central tolerance?
Tolerance to self-antigens mediated by the thymus, preventing autoimmunity.
p.3
Lymphoid Cells: T Cells, B Cells, and NK Cells
What types of cells are found in the lamina propria of the intestinal mucosa?
Lymphocytes (B cells, plasma cells, T helper cells) and macrophages.
p.3
Lymphoid Cells: T Cells, B Cells, and NK Cells
What are intraepithelial lymphocytes (IELs)?
Specialized T cells found in the epithelial layer of the intestinal mucosa.
p.3
Macrophages and Dendritic Cells
What is the function of M cells?
They act as a portal for microbes to enter the immune system.
p.11
Major Histocompatibility Complex (MHC)
What are MHC class I proteins responsible for?
Presenting peptide antigens to CD8 T cells.
p.11
Major Histocompatibility Complex (MHC)
Where are MHC class I proteins located?
On the surface of all nucleated cells except sperm cells and platelets.
p.2
Peripheral Lymphoid Organs
What are primary lymphoid follicles?
Follicles found before antigenic stimulus, mainly containing resting B cells.
p.2
B Cell Development and Function
What happens to resting B cells upon contact with an antigen?
They divide and become activated, differentiating into plasma cells and memory B cells.
p.2
T Cell Development and Maturation
What are nurse cells in the thymus?
Specialized epithelial cells with long membrane extensions that surround many thymocytes.
p.2
T Cell Development and Maturation
What is the role of thymic hormones?
They attract precursor T cells (progenitor T cells) from bone marrow.
p.9
Macrophages and Dendritic Cells
What happens to macrophages upon exposure to certain cytokines like interferon-γ?
They become activated, enhancing their phagocytic ability and increasing cytokine production against intracellular bacteria, virus-infected cells, and tumor cells.
p.10
Granulocytes and Their Role in Immunity
What are granulocytes?
A category of white blood cells characterized by the presence of granules in their cytoplasm.
p.1
Central Lymphoid Organs
What is the primary function of bone marrow in the immune system?
It is the site of hematopoiesis, where almost all blood cells originate from pluripotent hematopoietic stem cells.
p.6
T Cell Development and Maturation
What happens to the surviving cells after positive selection?
They undergo negative selection if they react to self-antigens.
p.10
Granulocytes and Their Role in Immunity
What is the role of interleukin-5 in relation to eosinophils?
It is believed to be the eosinophil chemotactic factor.
p.9
Macrophages and Dendritic Cells
What are some secretory products of activated macrophages?
Examples include enzymes, free radicals, cytokines, growth factors, and coagulation factors.
p.11
Major Histocompatibility Complex (MHC)
What additional genes are found in the MHC region II?
DO, DM, LMP, and TAP, which help in antigen processing and presentation.
p.4
Lymphoid Cells: T Cells, B Cells, and NK Cells
What is the lifespan of effector cells?
A few days to a few weeks.
p.11
Major Histocompatibility Complex (MHC)
What are the components of MHC class II molecules?
One α chain and one β chain, each consisting of two domains.
p.3
Peripheral Lymphoid Organs
What are the two structural arrangements of MALT?
Loose clusters of lymphoid cells and organized structures like tonsils and Peyer's patches.
p.9
Macrophages and Dendritic Cells
What is the role of follicular dendritic cells?
They are present in lymphoid follicles and differ from other dendritic cells in their specific location and function.
p.6
T Cell Development and Maturation
What do CD4+ helper T cells recognize?
Antigenic peptides presented with MHC-II molecules.
p.10
Major Histocompatibility Complex (MHC)
What are human leukocyte antigens (HLA)?
MHC coded proteins found on the surface of human cells.
p.13
Cytokines and Their Functions
What substances decrease the expression of MHC II molecules?
Corticosteroids and prostaglandins.
p.4
Lymphoid Cells: T Cells, B Cells, and NK Cells
What are the three types of lymphocytes based on function and cell membrane structure?
T lymphocytes, B lymphocytes, and natural killer (NK) cells.
p.4
Lymphoid Cells: T Cells, B Cells, and NK Cells
What are naive lymphocytes?
Resting B and T lymphocytes that have not interacted with any antigen.
p.11
Major Histocompatibility Complex (MHC)
What is the structure of MHC class I molecules?
Composed of an α chain and β2 microglobulin, with three extracellular domains (α1, α2, α3).
p.12
Cytokines and Their Functions
What are the four groups of cytokines?
Hematopoietin family, interferon family, chemokine family, and tumor necrosis factor family.
p.2
B Cell Development and Function
What is the germinal center in a lymph node?
The central area containing dividing B cells of various stages, where B cell activation occurs.
p.12
Cytokines and Their Functions
What are the two broad categories of cytokine functions?
Promote development of adaptive immunity and promote responses of innate immunity.
p.1
Central Lymphoid Organs
What is the role of the thymus in the immune system?
It is the site of proliferation and maturation of T cells.
p.10
Major Histocompatibility Complex (MHC)
What is the major histocompatibility complex (MHC)?
A group of genes coding for host cell surface molecules that bind to peptide fragments from pathogens.
p.1
Central Lymphoid Organs
What are the two types of lymphoid organs?
Central (primary) lymphoid organs and peripheral (secondary) lymphoid organs.
p.13
Major Histocompatibility Complex (MHC)
What is the relationship between HLA B27 and disease susceptibility?
It is strongly associated with ankylosing spondylitis, increasing risk by 90 times.
What is DiGeorge syndrome?
An immunodeficiency disorder characterized by congenital aplasia of the thymus.
p.9
Macrophages and Dendritic Cells
What are dendritic cells known for in the immune system?
They are specialized antigen presenting cells that capture, process, and present antigenic peptides to helper T cells.
p.11
Major Histocompatibility Complex (MHC)
What is the function of MHC class II molecules?
Presenting peptide antigens to CD4 T cells.
p.8
Macrophages and Dendritic Cells
What is the first step in the phagocytosis process?
Recognition: Attachment of the microbe to receptors on the macrophage.
p.9
Major Histocompatibility Complex (MHC)
What is the significance of MHC class II in macrophages and dendritic cells?
MHC class II molecules are essential for presenting antigenic peptides to helper T cells, facilitating their activation.
p.13
Cytokines and Their Functions
What effect does IL-4 have on MHC class II molecules?
Increases expression on resting B cells.
p.5
B Cell Development and Function
What type of antibodies do B cells produce after activation?
IgM and IgD initially, followed by IgG, IgA, and IgE with high affinity.
p.7
B Cell Development and Function
Where do the initial stages of B cell proliferation occur?
In the bone marrow, independent of exposure to antigen.
p.3
Peripheral Lymphoid Organs
What does MALT stand for?
Mucosa-associated Lymphoid Tissue.
p.12
Cytokines and Their Functions
What are the two effects cytokines can have on each other?
Synergism (augmenting each other's action) and antagonism (opposing each other's action).
p.10
Granulocytes and Their Role in Immunity
What do basophils contain that plays a major role in allergic responses?
Granules rich in histamine and other mediators.
p.12
Cytokines and Their Functions
What is the role of IL-2?
Induces proliferation of activated T H cells, T C cells, and some NK cells.
p.6
T Cell Development and Maturation
What are the subsets of CD4+ helper T cells?
TH1, TH2, and TH17 cells.
p.6
T Cell Development and Maturation
What do CD8+ cytotoxic T cells recognize?
Intracellular antigens presented with MHC-I molecules.
p.1
Other Cells of Immune System
What types of cells are included in the 'other cells of the immune system'?
Phagocytes (macrophages, neutrophils, eosinophils, basophils), dendritic cells, mast cells, and platelets.
p.7
B Cell Development and Function
What are Pro-B Cells?
The earliest bone marrow cells of B cell lineage that do not produce immunoglobulins but express a heterodimer Ig D /Ig E.
p.8
Lymphoid Cells: T Cells, B Cells, and NK Cells
From which lineage are NK cells derived?
A separate lymphoid lineage.
p.8
Macrophages and Dendritic Cells
What are the two main functions of macrophages?
Phagocytosis and antigen presentation.
p.9
Cytokines and Their Functions
What is the function of Interleukin 1 (IL-1) secreted by macrophages?
It promotes inflammatory responses, fever, and activates helper T cells.
p.5
T Cell Development and Maturation
What happens to double positive (DP) T cells during development?
They can undergo positive selection if their DE receptors recognize MHC molecules.
p.13
Major Histocompatibility Complex (MHC)
What condition is caused by defects in CIITA and RFX?
Bare lymphocyte syndrome.
p.11
Major Histocompatibility Complex (MHC)
What is the significance of β2 domain in MHC class II molecules?
It interacts with the CD4 molecule of helper T cells during antigen presentation.
p.8
Macrophages and Dendritic Cells
What type of killing is accomplished by lysosomal enzymes during phagocytosis?
Oxygen independent killing.
p.4
Lymphoid Cells: T Cells, B Cells, and NK Cells
What is the composition of most T cell receptors?
Two chains (D and E) with three regions: extracellular domain, transmembrane domain, and cytoplasmic domain.
p.13
Cytokines and Their Functions
What is the difference between cytokines and growth factors?
Cytokines are inducible and produced after cell activation, while growth factors are produced constitutively.
p.13
Major Histocompatibility Complex (MHC)
What type of antigens do MHC class I and class II present?
MHC class I presents endogenous antigens; MHC class II presents exogenous antigens.
p.12
Cytokines and Their Functions
What does the cascade effect in cytokine action refer to?
A series of effects mediated by different cytokines where one cytokine acts on a target cell to produce another cytokine.
p.4
Lymphoid Cells: T Cells, B Cells, and NK Cells
What are effector cells?
Activated lymphoblasts that function to eliminate antigens.
p.10
Granulocytes and Their Role in Immunity
What is the primary function of neutrophils?
They are the principal phagocytes of innate immunity.
p.3
Peripheral Lymphoid Organs
What happens if there is a defect in the spleen?
Increased incidence of bacterial sepsis, especially from capsulated bacteria.
p.1
Central Lymphoid Organs
What happens to hematopoietic activity in large bones as an individual ages?
It decreases, and after puberty, hematopoiesis is mostly confined to axial bones.
p.10
Granulocytes and Their Role in Immunity
Where are mast cells primarily located?
In skin, connective tissues of various organs, and mucosa.
p.4
Lymphoid Cells: T Cells, B Cells, and NK Cells
How do TCRs recognize antigens?
They respond to antigens that are processed and presented by antigen presenting cells.
p.10
Major Histocompatibility Complex (MHC)
Where are the HLA complex genes located in humans?
On the short arm of chromosome-6.
p.13
Major Histocompatibility Complex (MHC)
What is the primary difference between MHC class I and class II molecules?
MHC class I is present on all nucleated cells, while class II is present on antigen presenting cells (APCs).
p.4
Lymphoid Cells: T Cells, B Cells, and NK Cells
What happens to naive lymphocytes upon interaction with an antigen?
They become activated and transform into lymphoblasts.
p.5
Lymphoid Cells: T Cells, B Cells, and NK Cells
What is required for TCR to be active?
Both D and E chains must complex with the CD3 molecule.
p.9
Macrophages and Dendritic Cells
What is the origin of dendritic cells?
They originate from bone marrow, possibly developing from a separate lineage or from the macrophage lineage.
p.6
T Cell Development and Maturation
What are the two main types of effector T cells?
CD4+ helper T cells and CD8+ cytotoxic T cells.
p.5
Lymphoid Cells: T Cells, B Cells, and NK Cells
What is the life span of naive T cells?
Short, as they are dormant in the G0 phase.
p.13
Major Histocompatibility Complex (MHC)
How do viral antigens affect MHC-I expression?
They inhibit various components, leading to suppressed expression.
p.6
T Cell Development and Maturation
What are JG T cells?
A small subset of T cells that do not require antigen processing and MHC presentation.
p.13
Cytokines and Their Functions
What are the major classes of cytokines?
Lymphokines, monokines, interleukins, and chemokines.
p.13
Cytokines and Their Functions
What types of effects can cytokines have?
Autocrine, paracrine, and endocrine effects.
p.7
B Cell Development and Function
What happens to mature B cells after antigenic stimulus?
They transform into activated B cells (lymphoblasts) and differentiate into effector B cells or memory B cells.
p.4
Lymphoid Cells: T Cells, B Cells, and NK Cells
What distinguishes memory cells from naive cells?
Memory cells can rapidly transform into effector cells upon subsequent antigenic challenge.
p.6
T Cell Development and Maturation
What do double positive T cells express after maturation?
Either CD4 or CD8 molecules, becoming single positive mature T cells.
p.2
Peripheral Lymphoid Organs
What is the function of the spleen?
Acts as a physiological barrier, clearing microbial antigens through stimulation of T and B cells.
p.12
Cytokines and Their Functions
What effect does IL-4 have on B cells?
Promotes B cell activation and proliferation, and induces class switch to produce IgE, IgG4, IgG1.
p.7
B Cell Development and Function
What are B-1 cells and where are they found?
They are found mostly in the peritoneal cavity, coated by surface markers IgM and CD5, but lack IgD.
p.1
Components of the Immune System
What are the main components of the immune system?
Lymphoid organs, cells of the immune system, and cytokines.
p.3
Peripheral Lymphoid Organs
What is the primary function of the spleen?
To filter blood and destroy old or defective red blood cells.
p.11
Major Histocompatibility Complex (MHC)
What is the role of the α3 domain in MHC class I molecules?
It binds to the CD8 molecule on cytotoxic T cells during antigen presentation.
p.8
Macrophages and Dendritic Cells
What are the two types of macrophages based on their mobility?
Free (wandering) macrophages and fixed macrophages.
p.12
Cytokines and Their Functions
Which cells are the major producers of cytokines?
T H cells and macrophages.
p.1
Lymphoid Cells: T Cells, B Cells, and NK Cells
What are thymocytes?
Lymphocytes of the thymus, specifically immature cortical thymocytes.
p.1
Peripheral Lymphoid Organs
What are examples of peripheral lymphoid organs?
Lymph nodes, spleen, and mucosa-associated lymphoid tissue (MALT).
p.7
B Cell Development and Function
Where do immature B cells migrate to after leaving the bone marrow?
To peripheral lymphoid organs like lymph nodes and spleen.
p.9
Macrophages and Dendritic Cells
How do dendritic cells differ from macrophages in terms of their nature?
Dendritic cells are nonphagocytic and are the most efficient APCs, while macrophages are phagocytic.
p.5
Lymphoid Cells: T Cells, B Cells, and NK Cells
What distinguishes effector T cells from naive T cells?
Effector T cells are active and found in inflamed tissues, while naive T cells are dormant.
p.12
Cytokines and Their Functions
What is the function of IL-6?
Promotes B cell proliferation and antibody production.
p.6
T Cell Development and Maturation
What are regulatory T cells (TREG) responsible for?
Regulating the immune system and providing tolerance to self-antigens.
p.7
B Cell Development and Function
How do Pre-B Cells differentiate from Pro-B Cells?
By expressing the μ heavy chain.
p.7
B Cell Development and Function
What processes contribute to tolerance in B cells?
Receptor editing and negative selection.
p.13
Cytokines and Their Functions
What is redundancy in cytokine function?
Different cytokines producing the same effect on the same target cell.
p.7
B Cell Development and Function
What are plasma cells?
Antibody-secreting cells that are large, oval, and have a short life span of two to three days.
p.8
Macrophages and Dendritic Cells
How do macrophages differ from monocytes?
Macrophages are 5–10 times larger, contain more organelles, produce more enzymes and cytokines, have greater phagocytic activity, and live longer in tissues.
p.5
T Cell Development and Maturation
What are double negative (DN) T cells?
T cell precursors that do not express CD4 and CD8 surface markers.
p.11
Major Histocompatibility Complex (MHC)
What forms the antigen peptide binding groove in MHC class II molecules?
The cleft between the α1 and β1 domains.
p.6
T Cell Development and Maturation
What is the role of TH17 cells?
They produce IL-17 and IL-22, recruiting neutrophils and contributing to autoimmune diseases.
p.10
Major Histocompatibility Complex (MHC)
What is the significance of MHC molecules in transplantation?
They determine compatibility between graft and host tissues, affecting acceptance or rejection.
p.6
T Cell Development and Maturation
What is the significance of Foxp3 in TREG cells?
Deficiency leads to autoimmune diseases like IPEX syndrome.
p.7
B Cell Development and Function
What is the significance of tolerance in B cell development?
It prevents autoimmunity by ensuring that immature B cells do not react to self-antigens.
p.1
Cytokines and Their Functions
What are cytokines?
Soluble products secreted from various cells of the immune system, including interleukins and interferons.
p.13
Cytokines and Their Functions
What are cytokines?
Chemical substances that serve as messengers in the immune system.
p.13
Cytokines and Their Functions
What is pleiotropy in the context of cytokines?
The same cytokine having different actions on different target cells.
p.7
B Cell Development and Function
What are marginal-zone B cells?
B cells present at the edges of lymphoid follicles of the spleen, produced in response to polysaccharide antigens.
p.7
B Cell Development and Function
What characterizes Immature B Cells?
They express light chains and proliferate from Pre-B cells.
p.6
B Cell Development and Function
What is the primary function of B lymphocytes?
Mediating humoral immunity.
p.7
B Cell Development and Function
What is the B cell receptor composed of?
A heavy chain μ and its light chain, forming a complete IgM molecule complexed with heterodimer Ig D /Ig E.
