Pathology 2-2 Immunity

Pathology 2-2 Immunity - I. Immunity a. Properties...

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I. Immunity a. Properties (expected): antigen specific/antigen recognition, tolerance to self,  memory b. Antigen   elicits immune response (e.g. self cell, pathogen); protein, > 40,000  MW (responds to bigger things), repetitive epitopes (more chances for immune  system to react), multiple epitopes for triggering more immune responses (ex. 3  epitopes = 3 different immune responses) c. Epitopes: 10^11 molecules that the immune system can interact with = about a  trillion different epitopes needed   want more than one on each antigen; want  multiple copies of each on antigen d. Types of Response: endogenous (autologous), exogenous (homologous,  environment), shared (heterologous), xenologous (different species) e. Expected: humoral (antibody production) or cell-mediated response , clonal   expansion  (exact replicas, mitosis   swollen lymph nodes; more copies of cell to  response, more responses to same antigen, broader and stronger response),  memory f. Hypersensitivity: excess/inappropriate response g. Immune Deficiency: absent/inadequate response h. Autoimmunity: failure to distinguish self from non-self II. Humoral Response (B cells) a. Antibody Production i. B lymphocytes recognize antigen ii. Present antigen to T cells iii. T cells drive B cells to plasma cells iv. Plasma cells produce antibodies (until death) b. Antibodies i. Made from plasma cells (fully differentiated form of B cells) ii. Potential Complement Activation (antigen/antibody reaction) iii. Opsinization (enhance phagocytosis b/c macrophages have antibody  receptor) iv. Neutralization (make something no longer harmful; ex. Neutralizing  antibodies block cells from viruses) v. Killing of infected cell via antibody-dependent cell-mediated cytotoxicity vi. IgM – agglutination and lysis of bacteria; initiation of classical C’ pathway vii. IgA – blocking entry of microorganisms from respiratory tract, gut, eyes, urinary tract c. B Cell Activation/Process i. IgM antibodies are secreted (excited?) ii. Antibody (B cell making IgM) is clonally expanded (make copies of self –  more opportunity to encounter antigen) 1
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iii. Encounter Th2 help   make a better fitting antibody (TCR DOES NOT  have this) 1. Somatic Hypermutation (Affinity Maturation) a. Point mutations in variable region b. Check to antigen held by dendritic cell c. If okay, becomes plasma (or memory) cell d. If not okay, becomes anergic   apoptotic, removal 2. Class Switching a. Keep same Variable, Heavy, Light; switch to different  Constant (usually M to G) iv. Start in bone marrow (as stem cells) v. Gene rearrangement (see below) vi. Successful B cell receptor (BCR) – looks like antibody vii. Training for “tolerance of self”
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This note was uploaded on 03/23/2009 for the course BLD 204 taught by Professor Gerlach during the Spring '09 term at Michigan State University.

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Pathology 2-2 Immunity - I. Immunity a. Properties...

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