2-2 Adaptive immunity STUDENT.pdf

BIOL 1003 2- Inflammation 2-1 Innate immunity 2-2 Adaptive Immunity 2-3 Defects in Mechanisms of Defence Adaptive Immunity Purposes (in contrast to innate): Destruction of infectious microorganisms that are resistant to inflammation Long-term highly effecti...

BIOL 1003 2- Inflammation 2-1 Innate immunity 2-2 Adaptive Immunity 2-3 Defects in Mechanisms of Defence Adaptive Immunity Purposes (in contrast to innate): Destruction of infectious microorganisms that are resistant to inflammation Long-term highly effective protection against future exposure to the same microorganism Inducible (7-14d) Specific (1 lymphocyte : 1 antigen) -recognizes 100,000,000 different Ag before you’re even born! End products Activated lymphocytes (T cells, B cells) Immunoglobulins Adaptive Immunity Components: Humoral—B cells produce immunoglobulins (antibodies) that bind to antigens Cellular—T cells produce subpopulations (effector T cells) -Cytotoxic T cells- Kill target directly -Helper T cells- Stimulate other leukocytes -And more! Both produce memory cells and interact with each other Adaptive Immunity Antigens Bind with antibodies, receptors on T and B cells Not necessarily immunogens Immunogens All are antigens (e.g. peanut allergy- antigen is immunogenic in the allergic, but not in non- allergic) Induce production of antibodies, T and B cells Depends on foreignness, molecular size, quantity Entry route (intravenous, intradermal, oral) stimulates different lymphoid tissue Genetics Other factors (nutrition, concurrent disease, drugs) Antigens Antigenic determinant (epitope) Antigenic binding site (paratope) Self-antigen Tolerance Central and peripheral tolerance Humoral Immunity Antigen-Antibody Binding: Antigenic determinant (epitope) Antigen-binding site (paratope) FC is the generic region of AB that is recognized by cells via FcR Antibody Functions Antibody functions: Direct Neutralization Agglutination Precipitation Indirect Inflammation Phagocytosis Complement Degree of antibody protection is assessed by an antibody titer Immunoglobulin A (IgA) Two classes: IgA1 molecules are found predominantly in the blood IgA2 molecules are found predominantly in normal body secretions IgAs found in body secretions are dimers anchored by a J chain and a “secretory” piece Secretory piece may function to protect IgAs against enzyme degradation Primary constituent of the secretory immune system (Meant to prevent infection instead of react to it) Secretory (Mucosal) Immune System Lymphoid tissues that protect the external surfaces of the body Antibodies present in tears, sweat, saliva, mucus, and breast milk IgA is the dominant mucosal immunoglobulin Small numbers of IgG and IgM are present Immunoglobulin D (IgD) Limited information on IgD function Low concentration in the blood Located primarily on the surface of developing B lymphocytes Function as one type of B cell antigen receptor Immunoglobulin E (IgE) Least concentrated of the immunoglobulin classes in the circulation Mediator of many common allergic responses Defender against parasites IgE Function Provides protection from large parasites Initiates an inflammatory reaction to attract eosinophils When produced against innocuous environmental antigens, they are a common cause of allergies Fc portions of IgEs are bound to mast cells Immunoglobulin G (IgG) Most abundant class (80%-85%) Accounts for most of the protective activity against infections (best opsonin) Transported across the placenta Four classes: IgG1 IgG2 IgG3 IgG4 Immunoglobulin M (IgM) Largest of the immunoglobulins Pentamer stabilized by a J chain First antibody produced during the primary response to an antigen Synthesized during fetal life Best activator of complement system YY C1 Antibody Types Mnemonic Most abundant G Most abundant (most activity in immune response is phagocytic) A 2 subtypes (blood+secretion), dimer M aMbulance, first responder, best at C activation because VV D On B E Al-er-GEE, defends against parasites (just like Eosinophils) Least abundant Antigen presentation and recognition Major histocompatibility complex (MHC) -aka human leukocyte antigens (HLAs) -display antigen to leukocytes Clusters of differentiation (CD) CD4 -expressed by Th -recognizes extracellular threats presented by MHC II CD8 -expressed by Tc -recognizes intracellular threat threats presented by MHC I Antigen Processing and Presentation Figure 07-12. Primary and Secondary Responses Primary response Initial exposure Latent period or lag phase B cell differentiation is occurring After 5 to 7 days, an IgM antibody for a specific antigen is detected An IgG response equal or slightly less follows the IgM response Primary and Secondary Responses Secondary response More rapid Larger amounts of antibody are produced Rapidity is caused by the presence of memory cells that do not have to differentiate IgM is produced in similar quantities to the primary response, but IgG is produced in considerably greater numbers Adaptive Immunity Active immunity Exposure to antigen Immunization Passive immunity Preformed antibodies or T cells are administered -Colostrum