How do the innate and adaptive immune responses work together?
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They work side by side through a feedback mechanism.
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How do the innate and adaptive immune responses work together?
They work side by side through a feedback mechanism.
What role do dendritic cells (DCs) play in the immune system?
They function as a 'bridge' between innate and adaptive immune responses.
What is the significance of the interactions between innate and adaptive immunity?
They enhance the overall immune response.
What are neutrophils also known as?
PolyMorphonuclear Neutrophilic Leukocytes (PMNs).
What percentage of total white blood cells do neutrophils constitute?
~60%.
How are neutrophils replaced in the body?
Through granulopoiesis at a rate of 5 × 10^10 per day.
What is the key location for B lymphocytes?
Blood, Lymph, and Lymph Nodes (LNs).
What happens to neutrophils after they complete their mission?
They die and form pus.
What is the role of neutrophils in response to infection?
They are the first to respond and are a hallmark of acute inflammation.
What major component of pus do neutrophils represent?
They are a major component of pus.
What are the key immunological functions of B lymphocytes?
Humoral immunity, production of antibodies, and keeping immunological memory.
What mechanisms do neutrophils use for phagocytic killing?
Intracellular, oxidative, and non-oxidative mechanisms.
How do neutrophils perform cytotoxic killing?
Through degranulation and neutrophil extracellular traps (NETs).
What is the key location for T lymphocytes?
Blood, Lymph, and Lymph Nodes (LNs).
What are the key immunological functions of T lymphocytes?
Cellular immunity, secretion of cytokines, and elimination of cancer cells and virally infected host cells.
What do lymphoid-derived lineages originate from?
A common lymphoid precursor (CLP).
What are white blood cells also known as?
Leukocytes.
What is the primary function of leukocytes?
To recognize and destroy invading antigens and neoplastic cells, and alert other immune cells.
Name three types of lymphoid-derived cells.
T lymphocytes (T cells), B lymphocytes (B cells), and Natural Killer (NK) cells.
What role do cytokines play in the immune system?
They function as intercellular mediators or signaling molecules.
What is normal flora?
Normal flora refers to the microorganisms that are naturally present in various parts of the body.
What are T lymphocytes also known as?
T cells.
What triggers an acute inflammatory response in the innate immune system?
The entry of foreign bacteria (antigens) or tissue damage.
How do leukocytes migrate to affected tissues?
By squeezing out through blood vessel walls in response to chemical signals (Chemotaxis).
Where can normal flora be found in the body?
On the skin, eyes, GI tract, outer ear, nose, mouth, throat, urethra, and vagina.
What are B lymphocytes also known as?
B cells.
What is the function of lymphatic vessels?
To collect excess interstitial fluid from tissues and return it as lymphatic fluid to the blood vasculature.
What are the cardinal signs of acute inflammation?
Redness, warmth, pain, swelling, altered function.
What type of cells do Natural Killer (NK) cells belong to?
Lymphoid-derived lineages.
What are the criteria for classifying different populations of leukocytes?
Developmental origin, cytological appearance, location, and immune functions.
Which bacteria are commonly found on the skin as part of normal flora?
Propionibacterium and Staphylococcus epidermidis.
How does interstitial fluid form?
Fluid from the blood seeps out of capillaries into the tissues, creating interstitial fluid.
What is fever in the context of the immune response?
A host defense mechanism to infectious disease, especially bacterial infections.
Which leukocytes are considered tissue resident and not found in the blood?
Mast cells and macrophages.
What are examples of normal flora in the large intestine?
Escherichia coli and Clostridium difficile.
What is the complement system?
A system of interacting proteins produced by the liver that circulate in the blood.
What mechanisms help in the movement of lymphatic fluid?
Smooth muscles, respiratory pump, and skeletal muscle pump.
What normally regulates body temperature and what happens during infection?
The temperature-regulation center in the brain normally holds at 37°C but raises during infection.
What is the primary function of the skin in the innate immune system?
To serve as an outer barrier composed of densely packed squamous epithelial cells and impenetrable keratinized cells.
How are complement proteins activated?
They are inactive when intact and become active when fragmented.
Which bacteria are found in the vaginal cavity as part of normal flora?
Lactobacillus spp. and Candida albicans.
What happens to excess interstitial fluid in the lymphatic system?
It is sucked by lymphatic capillaries and transferred to collecting vessels, then filtered through draining lymph nodes.
What causes the increase in body temperature during infection?
Pyrogens produced exogenously by infecting microbes and endogenously by macrophages and monocytes.
What role do mucosal epithelia play in the innate immune defense?
They line the digestive, respiratory, and urogenital tracts, secreting mucus that helps trap microbes and aids in their mechanical removal.
What is Chediak-Higashi Syndrome?
A condition caused by defects in lysosomal trafficking regulator (LYST), affecting phagocyte function.
What role do lymph nodes play in the immune response?
They filter lymphatic fluid and activate adaptive immune cells if antigens are present.
What are the main functions of activated complement proteins?
Where are antibodies found in vertebrate animals?
In blood serum, tissue fluids, and mucosal surfaces.
What are the three key responses of the Innate Immune System?
Complement System, Acute Inflammatory response, Phagocytosis, and Fever.
What are some examples of mechanical removal mechanisms in the innate immune system?
Peristalsis, flushing of the urinary tract, and mucociliary clearance of the respiratory tract.
What role does LYST play in the immune system?
It is critically involved in lysosomal transport and vesicle formation during phagocytosis.
What roles do basophils and mast cells play in the immune system?
They are involved in allergic disorders and the inflammatory response to parasitic infections.
Which complement proteins are involved in stimulating the inflammatory response?
C3a and C5a.
Where do eosinophils preferentially reside?
In the dermis and lamina propria.
What is one of the primary functions of antibodies?
To recognize and bind to antigens, assisting with phagocytosis.
What type of cells are Natural Killer Cells?
Lymphocytes that function in innate immunity.
What is the role of the Complement System in the Innate Immune Response?
It helps to enhance the ability of antibodies and phagocytic cells to clear pathogens.
What components make up the mucus secreted by mucosal epithelia?
Glycoproteins, proteoglycans, and protective enzymes.
What role does C3b play in the complement system?
It opsonizes pathogens, aiding in phagocytosis.
What is extracellular fluid (ECF) found within blood vessels composed of?
Plasma, platelets, and cells (RBC, WBC).
What is one of the primary immune functions of Natural Killer Cells?
Elimination of virally-infected and neoplastic (cancer/tumor) cells.
What are the clinical manifestations of Chediak-Higashi Syndrome?
Recurrent, life-threatening infections, neurological defects, and oculocutaneous albinism.
How do antibodies neutralize pathogens?
By binding to them and neutralizing their effects.
What is the Acute Inflammatory response?
A rapid response to tissue injury or infection that involves the recruitment of immune cells.
What condition is characterized by an increased number of eosinophils?
Eosinophilia.
What happens during FcR binding with IgE?
It results in acute allergic reactions.
What system do antibodies assist in activating?
The complement system.
What types of infections are patients with Chediak-Higashi Syndrome susceptible to?
Infections caused by fungi, Gram-negative bacteria, and Gram-positive bacteria such as Staphylococcus and Streptococcus spp.
What is phagocytosis?
The uptake of pathogens by phagocytic cells leading to their destruction.
What mechanism do Natural Killer Cells use for direct cytotoxicity?
Perforin-granzyme mechanism.
What is Phagocytosis?
The process by which certain immune cells engulf and digest pathogens or debris.
In which situations do eosinophils increase in number?
During allergic responses and infections with helminthic parasites.
What are the primary lymphoid organs involved in?
The formation and development of immune cells.
What is interstitial fluid (ISF) and its function?
ECF that surrounds cells in the tissues, facilitating the transfer of nutrients and wastes to/from cells and capillaries.
What induces cross-linking of multiple Fc ε Rs?
Repeated exposure to allergens, which are often polyvalent.
What is mucociliary clearance?
A mechanism in the respiratory tract that helps remove microbes through the action of cilia and mucus.
What is cytolysis in the context of the complement system?
The process of lysis and death of target cells, facilitated by the membrane attack complex (C5b, C6-C9).
What abnormalities are observed in neutrophils of patients with Chediak-Higashi Syndrome?
Excessive nuclear segmentation and giant lysosomes in the cytoplasm.
What is antibody-dependent cellular cytotoxicity (ADCC)?
A process where antibodies assist in killing infected host cells.
How does the perforin-granzyme mechanism work?
Perforin forms pores in the target cell, allowing granzyme to enter and induce apoptosis.
What role does opsonization play in phagocytosis?
It mediates the uptake of pathogens by phagocytic cells.
What is the purpose of Fever in the Innate Immune Response?
To create an unfavorable environment for pathogens and enhance immune function.
What is one of the immune functions of eosinophils?
Cytotoxic killing through degranulation and ADCC.
Name the primary lymphoid organs.
Red bone marrow and thymus.
What is lymphatic fluid (lymph) formed from?
Drainage of excess interstitial fluid (ISF).
How does Chediak-Higashi Syndrome affect phagocyte function?
It leads to grossly impaired phagocyte function and increased susceptibility to infections.
What do basophils and mast cells release during degranulation?
Inflammatory mediators including histamine and other cytokines.
What are the two mechanisms of pathogen destruction during phagocytosis?
Oxidative and non-oxidative killing mechanisms.
What is Antibody-dependent cell-mediated cytotoxicity (ADCC)?
A mechanism where NK cells use Fc Ƴ III receptors to bind antibody-coated antigens on infected or cancer cells.
What is the role of Memory T cells in the adaptive immune response?
They keep immunological memory of the antigen and differentiate into effector T cells upon re-encountering the antigen.
Where is the spleen located?
In the lower left quadrant of the abdomen.
What are the two widely different types of dendritic cells?
Conventional (myeloid) dendritic cells (cDCs or mDCs) and plasmacytoid dendritic cells (pDCs).
What type of parasites do eosinophils help eliminate?
Extracellular parasites, especially helminths.
What are secondary lymphoid organs responsible for?
Sites where naïve adaptive immune cells interact with antigens and get activated.
How does lymphatic fluid return to the cardiovascular system?
Via subclavian veins where it mixes with venous blood.
How do mast cell stabilizers or antihistamines work?
They limit the ability of mast cells and basophils to degranulate, preventing the release of histamine and related inflammatory mediators.
What do myeloid-derived lineages originate from?
A common myeloid precursor (CMP).
What is the primary immune organ responsible for hematopoiesis?
Red bone marrow (RBM).
What are antigen-presenting cells (APCs)?
Cells like dendritic cells and macrophages that present epitopes on their surface after phagocytosis.
What do activated NK cells release to induce apoptosis?
Granzyme and perforin.
How do Memory T cells assist during re-infection?
They help with the activation of B cells in re-infection with the same antigen.
What condition typically occurs during infections with bacteria and fungi?
Neutrophilia.
What are the two distinct regions of the spleen?
Red pulp and white pulp.
What is the mechanism of ADCC in eosinophils?
Binds targets using FcɛRI and antibodies IgE or IgG, then kills targets by releasing cytotoxic proteins and cytokines.
What is the primary function of conventional dendritic cells (cDCs)?
To secrete cytokines that help with immune response against various pathogens and function as antigen-presenting cells (APCs).
Give examples of secondary lymphoid organs.
Lymph nodes, spleen, and mucosal-associated lymphoid tissues (MALTs).
Which immune cells are carried in lymph?
Dendritic cells (DCs), B cells, and T cells.
How do APCs connect innate immunity with adaptive immunity?
By bringing naïve T lymphocytes in contact with antigens, aiding in their activation and proliferation.
Give examples of mast cell stabilizers or antihistamines.
Cromolyn and Diphenhydramine.
Name three types of granulocytes.
Neutrophil, eosinophil, basophil.
What type of stem cells are found in red bone marrow?
Hematopoietic stem cells (HSC).
What is neutropenia?
A decreased number of neutrophils.
What is the function of T helper cells?
They secrete cytokines that shape immune responses by enhancing or suppressing immune cell functions.
What is the primary function of the red pulp in the spleen?
Removes spent RBC, recycles iron, stores platelets, and stores blood for mobilization during hemorrhagic shock.
What do plasmacytoid dendritic cells (pDCs) primarily respond to?
Viruses, by producing large amounts of type-I interferons (IFN-alpha, IFN-beta).
What is the primary difference between primary and secondary antibody responses?
A secondary antibody response shows significantly increased levels of antibodies compared to the primary response.
What are tertiary lymphoid tissues?
Spontaneous organized lymphoid structures that arise in chronic inflammation, select cancers, and autoimmune diseases.
What is a macrophage also referred to as?
M Φ.
What is hematopoiesis?
The process of development of blood elements from hematopoietic stem cells.
Why are T helper cells referred to as 'central gate keepers'?
Because they play a crucial role in regulating immune responses through cytokine secretion.
What can cause neutropenia in cancer patients?
Treatment with antiproliferative agents.
What is the role of the white pulp in the spleen?
It is analogous to the lymph node, with immune cells arranged in nodules.
Do plasmacytoid dendritic cells (pDCs) function as antigen-presenting cells?
No, they do not function as APCs.
What is one role of the lymphatic system in fluid balance?
Drains and cleans excess interstitial fluid (ISF) to maintain fluid balance and returns it to the cardiovascular system.
What induces an elevated secondary immune response?
Repeated exposure to the same antigen.
Which cell type is a precursor to platelets?
Megakaryocyte.
How do tertiary lymphoid tissues compare to secondary immune organs?
They are less organized compared to secondary immune organs.
What process occurs in red bone marrow related to B cells?
B cell lymphopoiesis.
What is the primary function of Cytotoxic T cells?
They kill host cells infected with viruses or intracellular bacteria, as well as cancer/tumor cells.
What is Severe Congenital Neutropenia?
A genetic disorder affecting granulopoiesis, leading to neutropenia.
How does the spleen differ in terms of lymphatic drainage?
It is serviced by blood vessels but does not have afferent lymphatic vessels, hence does not drain lymphatic fluid.
How much interstitial fluid does the lymphatic system return to systemic circulation daily?
~ 8 liters.
What are the immune functions of dendritic cells as professional phagocytes or APCs?
Phagocytic killing, antigen processing and presentation, co-stimulation, and cytokine delivery.
What type of cell is a dendritic cell (DC)?
A myeloid-derived lineage cell.
Where is red bone marrow located in adults?
In open spaces formed between trabeculae of spongy bone in vertebrae, epiphyses of long bones, innominate bones of the pelvis, and flat bones of the skull, sternum, and ribs.
What are the major lymph node regions?
Cervical, Supraclavicular, Axillary, Popliteal, Femoral, Inguinal, Mesenteric, Supratrochlear, Mediastinal.
What is the underlying mechanism for the elevated antibody response upon repeated antigen exposure?
Immunological memory.
What does GALT stand for?
Gut-Associated Lymphoid Tissue.
What type of antigens do Cytotoxic T cells target?
Intracellular antigens.
What infections are particularly dangerous for individuals with Severe Congenital Neutropenia?
Life-threatening bacterial infections, especially those caused by Staphylococcus spp.
What are the functions of the spleen?
Removing senescent RBC, storing RBC, WBC, and platelets, and mounting immune responses against blood-borne antigens.
What immune cells are supported by the lymphatic system's circulation?
B cells, T cells, and dendritic cells (DCs).
How many lymph nodes are typically found in the human body?
500-800.
What type of cell is an erythrocyte?
Red blood cell (RBC).
How does the distribution of red bone marrow differ between adults and infants?
Infants have a distinct distribution pattern compared to adults.
How do antigen-specific B cells and T cells respond to repeated encounters with the same antigen?
They respond more quickly and robustly, known as an anamnestic reaction.
What is co-stimulation in the context of dendritic cells?
The necessary secondary signal delivered by co-stimulatory molecules to help activate T cells.
Where is GALT located?
Across the gut wall.
What is the size and shape of lymph nodes?
Small (1-2 cm), bean-shaped organs.
What type of immune responses does the spleen primarily mount?
Adaptive immune responses (B and T cell activation) against antigens present in blood.
How does the lymphatic system support adaptive immune function?
By facilitating the circulation of immune cells to secondary immune organs.
How can neutropenia be treated?
With rhG-CSF (recombinant human granulocyte colony-stimulating factor) to stimulate granulopoiesis.
What advantage does a secondary antibody response provide to the host?
It enables elimination of pathogens before the host becomes symptomatic, providing immunity.
What is the role of monocytes in the immune system?
They differentiate into macrophages and dendritic cells.
How do dendritic cells promote T cell activation?
By secreting cytokines.
What are MALTs?
Mucosa-Associated Lymphoid Tissues.
What do draining lymph nodes do?
Filter lymphatic fluid transported via lymphatic vessels.
What is the significance of fluid uptake by the lymphatic system?
It allows for antigens present in tissues to be delivered to secondary immune organs, aiding in the activation of T and B cells.
What principle underlines the concept of vaccination?
The principle of immunological memory and the secondary antibody response.
What type of immune cell is a mast cell?
A myeloid-derived lineage cell involved in allergic responses.
What is the relationship between neutrophilia and susceptibility to infections?
Neutrophilia indicates an increased number of neutrophils, while neutropenia indicates a decreased number, leading to increased susceptibility to infections.
What comprises the first line of defense in immune defenses?
Physical barriers, chemical and physiological barriers, and normal microbiota.
Where are MALTs found?
In the lamina propria of mucosal membranes lining the GI, respiratory, and urogenital tracts.
What are cell surface markers?
Surface glycoproteins that immune cells use to communicate and interact.
What is the role of Memory B cells in the adaptive immune response?
They keep immunological memory of the antigen and differentiate into effector B cells upon re-encountering the antigen.
What initiates immune responses in the lymphatic system?
The delivery of antigens to secondary immune organs.
What is the role of normal microbiota in immune defense?
They block infection and help defend by colonizing barriers.
What types of cells reside in the lymphoid follicles of MALTs?
B cells.
What types of cells are primarily found in lymph nodes?
B and T cells, some macrophages, and dendritic cells (DCs).
What does CD stand for in CD markers?
Cluster of differentiation.
What do Plasma B cells secrete?
Antibodies specific to the antigens.
What constitutes the second line of defense in immune defenses?
Innate immune cells such as granulocytes, phagocytes, and NK cells.
What types of cells reside in the surrounding follicles of MALTs?
T cells and dendritic cells (DCs).
What do cells inside lymph nodes respond to?
Antigens present in interstitial fluid (ISF) drained from upstream tissues.
What is immunophenotypic analysis?
The use of antibodies directed against CDs to phenotype cells.
What are antibodies?
Y-shaped glycoproteins produced by activated B cells (plasma cells) in response to specific antigens.
What are the main cells of the Adaptive Immune System?
B cells and T cells.
What are the two main types of immune cells based on granularity?
Granulocytes and Agranulocytes.
What is the shape and location of the thymus?
Butterfly-shaped endocrine gland situated anterior to the heart.
What is the function of innate immune cells?
They recognize and help destroy any pathogen that crosses the barriers.
What specialized epithelial cells are found in Peyer's patches?
Microfold cells (M cells).
What techniques are applied in immunophenotypic analysis?
Flow cytometry and microscopy, using immunohistochemistry (IHC) and immunofluorescence (IF).
What is the role of lymph nodes in the immune response?
Sites for B and T cell activation and major sites for mounting adaptive immune responses.
What can the antigen-specific B cell receptor (BCR) on plasma cells be secreted as?
An antibody (Ab) or immunoglobulin (Ig).
What do B cells differentiate into upon activation?
Memory B cells and Plasma B cells.
Which immune cells are classified as granulocytes?
Neutrophils, Eosinophils, and Basophils.
What are macrophages also known as?
Large-eaters or histiocytes.
What makes up the third line of defense in immune defenses?
Adaptive immune cells, specifically B and T cells, and their products.
What is the role of M cells in MALTs?
To transport antigens.
What types of cells are found in the thymus?
Progenitor T cells (thymocytes), stromal cells, thymic epithelial cells, macrophages (M Φ), and dendritic cells (DCs).
What are the CD markers for Helper T cells?
CD3, CD28, CD4, CD40L, CXCR4/CCR5.
How many major structural classes or isotypes of antibodies are there?
Five: IgA, IgD, IgE, IgG, and IgM.
What types of T cells are produced upon activation?
T helper (Th) cells and Cytotoxic T (Tc) cells (or Cytotoxic T lymphocytes, CTLs).
What is the appearance of neutrophils under routine staining?
Polymorphonuclear with pink cytoplasmic granules.
What are the main types of cells involved in the second line of innate immune defense?
Granulocytes (Neutrophils, Eosinophils, Basophils), Macrophages, Dendritic cells, and Natural Killer cells.
Where do resident macrophages typically reside?
In tissues and secondary immune organs.
What is the role of B and T cells in the immune response?
They help defend the host when the first two lines are overpowered and keep a memory of the pathogen.
What is the function of CD19 in B cells?
It is involved in binding antigen and is a receptor for EBV.
What happens to activated B and T cells in MALTs?
They traffic to the draining mesenteric lymph node to amplify the adaptive immune response.
What does humoral immunity typically target?
Extracellular pathogens.
