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MCM B2-091 Immunology
Terms in this set (42)
adaptive (acquired) immune response
The response of antigen-specific B and T lymphocytes to antigen generated over 3-4 days, including the development of immunological memory.
innate immune response
A quick, general immune response that targets groups of pathogens and has no memory.
humoral immune response
The branch of acquired immunity that involves the activation of B cells and that leads to the production of antibodies, which defend against bacteria and viruses in body fluids.
Skin: major barrier
Muscous: traps inhaled particles (like dust, allergens, bacteria, or viruses) and keeps them from getting deeper into your lungs
Stomach Acid: lethal to many pathogen but some bacteria can be resistant or having too much of some good bacteria can make them go out of control
Our own biota: if something is removed from out biota, something else will HAVE to replace it and that could be very bad.
The two types of white blood cells are a part of the body's adaptive immune system and use memory:
B lymphocytes form in the bone marrow and release antibodies that fight bacterial infections;
T lymphocytes form in the thymus and other lymphatic tissue and attack cancer cells, viruses, and foreign substances.
Natural Killer (NK) cells are also developed from the lymphocytes, but they are a part of the body's innate immune system.
Cells of the immune system communicate via...
...soluble molecules and surface molecules (CD# and Initialisms eg LFA-1, MHC, ICAM-1).
Antibodies: precise specificity and bind to antigens
Cytokines: communicate between cells, paracrine, autocrine, endocrine
Chemokines: attract migrating cells
Colony Stimulating Factor (CSF): recruit cells from the bone marrow
What are the parts of an antibody?
Two major domains produced by B cells:
Fab - antigen binding fragment with extreme variability
Fc - crytalizable fragment that binds to cells via the FcR (Receptor) + gives the antibody its specialized properties. It is non-variable and important in cell binding and C' activation.
The two domains are made up of two H (heavy) and 2 L (light) chains. The chains are bound together by disulfide bonds. Light chains are encoded for by leader, variable, and joining genes, whereas heavy chains also are encoded by diversity genes.
Opsonization, type II hypersensitivity
2 gamma H chains
Fc with bind to the Fc gamma Rs:
FcgammaRI = CD64
FcgammaRII = CD32
FcgammaRIII = CD16
An Fc receptor is a protein found on the surface of certain cells - including B lymphocytes, macrophages, neutrophils, and mast cells that contribute to the protective functions of the immune system.
They bind to antibodies attaches to INFECTED CELLS or invading pathogens.
Their activity stimulates phagocytic/cytotoxic cells to destroy the infected cells and invading pathogens through ADCC of phagocytosis.
An exaggerated response by the immune system to a particular substance
Type I: immunity to helminths (allergens)
Type II: Cytotoxic ANTIBODY mediated cell destruction such as autoimmune conditions caused by opsonization (ADCC)
Type III: immunity to bacterial toxins such as Lupus and soluble antigens
Type IV: delayed immunity to intracellular bacteria/protozoa that is T-cell mediated (no antibodies) such as Crohn's disease
Natural Killer Cells (NK cells)
Lymphocytes with ONLY CD56 receptors, that can recognize host cells with pathogens inside of them (ADCC) and release cytokines.
NK cells can be switched off by healthy cells or any cells expressing MHC Class I.
A group of about 30 blood proteins that may amplify the inflammatory response by recruiting inflammatory cells, enhance opzonization, or directly lyse extracellular pathogens.
[innate immune system] Found within the lymph nodes and tissues, they are phagocytes that are the first to destroy bacteria, cancer cells, and other foreign matter in the lymphatic stream. They use PRRs.
[innate immune system] The most abundant type of white blood cell that is phagocytic and tend to self-destruct as they destroy foreign invaders, limiting their life span to a few days. They are recruited to sites of infection by cytokines and related to diabetes.
They can be recruited from the bone marrow (by G-CSF and GM-CSF) and then brought to the sites of infection (by IL-8 and C5a through chemotaxis).
Selectins and integrins allow the neutrophils to stop at the correct sites and opsonization leads to phagocytosis.
[innate immune system] Specialized white blood cells that patrol the body searching for antigens that produce infections and present the antigens they find to T cells for memory. They use PRRs.
Mast Cells and Basophils
[innate immune system] Take part in stimulation and coordination of inflammation by release of histamine, heparin, leukotrienes, prostaglandins. They are particularly important for allergies.
Pattern Recognition Receptors (PRRs)
Proteins expressed by cells of the innate immune system that evolved before adaptive immunity. they include toll-like receptors (TLR), nod-like receptors (NLR), and RIG-I receptors (RLR).
TLR: found on cell surfaces and organelles of our body cells; specific TLR interact with specific factors (i.e. TLR-4 interact with LPS on bacteria)
NLR: cytoplasmic sensors of PAMPS and DAMPS
They are used by dendritic cells and macrophages
Pathogen Associated Molecular Patterns
Highly conserved patterns on microbes - cell wall, peptidoglycan, flagella, lipopolysaccharide that are recognised by phagocytes, which triggers phagocytosis.
Examples: LPS, peptidogylcan, dsRNA
Damage Associated Molecular Patterns
Expressed by stressed host cells or cells that went through damage and stuff has lysed out.
Examples: Uric Acid, extracellular DNA, RNA, and ATP
acute phase response
Acute phase responses by dendritic cells and macrophages are induced by:
TNFalpha - activate acquired immune system + pyrexic
IL-6 - pyrexia via PGE2
IL-1 - pyrogenic + inflammation
IL-8 - chemokine for neutrophils
...which cause release of acute phase response proteins c-reactive protein (CRP)
...and can be detected by erythrocyte sedimentation rate (ESR), where a higher than normal rate indicates there are more than normal amounts of inflammatory proteins in the blood.
Leukocyte Adhesion Deficiency (LAD)
Autosomal recessive genetic mutations where there are no integrins for neutrophils to adhere to in the blood vessel at the site of infection.
This can cause recurrent bacterial infections, poor wound healing and peripheral blood neutrophilic leukocytosis.
An immune response in which the binding of antibodies to the surface of a microbe/pathogen allows neutrophils and macrophages to recognize ones they need to kill.
antibody (acquired) and complement system (cytokines - innate)
T (Thymus) Cells
Acquired Immune System
Have antigen receptors that bind to specific antigens on the pathogen:
CD4+ expressed on the pathogen
- MHC Class II
- Control the cell
CD8+ expressed on the pathogen
- MHC Class I
- Kill the cell (such as infected B cells)
Acquired Immune System
Have antigen receptors that bind to specific antigens on the pathogen:
- used to treat B cell proliferative diseases (like cancers) by killing off all the B cells so that they don't keep on producing antibodies against the body
Joins the blood stream at the left subclavian vein, where muscle contraction forces the cells into the blood.
Cells can re-enter the lymph nodes through the high endothelial venules at the lymph nodes.
Primary Lymph Organs
Secondary Lymph Organs
Tertiary Lymph Organs
Aggregates of lymphocytes at chronic inflammation areas
B cell receptor (BCR)
Molecule on the surface of a B cell that binds to a specific antigen.
- surface bound
- can bind two antigens
- interacts with Ig alpha and Ig beta surface molecules to cause signal transduction
T cell receptor (TCR)
Molecule on the surface of a T cell that can bind to a specific antigen fragment in combination with an MHC molecule (heterodimer)
- binds one antigen
- signaling through a CD3 complex
- expresses CD4+ and CD8+ receptors as well
Human Leukocyte Antigen (HLA)
Molecules found on nucleated cells in the body that help the immune system to recognize whether or not a cell is foreign to the body. These antigens are on chromosome 6 and are inherited from one's parents. HLA are used to determine the compatibility of kidneys and pancreases for transplantation from one individual to another.
HLAs have three regions:
Region 1 = MHC Class I region (b chain beta2-microblulin is NOT coded here, only a chain is coded here) found on ALL nucleated cells and binds to CD8+ T cells
Region 2 = MHC Class II region that is present on APC cells (cells that present antigen to CD4+ T cells)
Region 3 = MHC Class III region for other, non-surface protein coding that are important for immunity
MHC Class I
Found on ALL nucleated cells in the body
It binds to the CD8+ molecule on T cells
Presents endogenous toxins
MHC Class II
Display antigens derived from extracellular pathogens
Binds to CD4+ molecule on T cells
first antibody produced
pentameric = several molecules can bind at the same time
Type I hypersensitivity
CD4+ helper T cells
Cells that protect against infections and activate the body's immune response. HIV kills these cells, so a high count usually means better health.
Activate cells related to cell-mediated immunity
Type IV Hypersensitivity (delayed hypersensitivity - B cells respond early whereas these helper T cells response later)
Induced by IL-12
Secretes IFNgamma, TNF, and IL-2 to control macrophages and Th2
Allergies, response to antibodies
Type I Hypersensitivity
IL-4 and IL-13 - allergies
IL-5 - stimulate eosinophils
Assist in antibacterial responses - bacteria and fungi
Important in inflammation
Regulatory T cell (suppressor T cell)
Secretes TGFbeta and IL-10
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