Immunoglobulin E (IgE) • Least concentrated of the immunoglobulin classes in the circulation • Mediator of many common allergic responses • Defender against parasites • Involved in the inflammatory process • IgE located on mast cells, when activated, IgE causes degranulation of the mast cells releasing histamine • Allergic reaction, rhinitis, watery eyes, itchy nose • Inflammatory response • Parasites • Most common cause of allergies
18 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
19 Immunoglobulin G (IgG) • Most abundant class (80%-85%) • Accounts for most of the protective activity against infections • Transported across the placenta • Four classes: • IgG1 • IgG2 • IgG3 • IgG4
20 Immunoglobulin M (IgM) • Largest of the immunoglobulins • Pentamer stabilized by a J chain – don’t worry about this, just know its large • First antibody produced during the primary response to an antigen • Synthesized during fetal life • IgG and IgM synthesized in utero
21 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 immunoglobulin • Small numbers of IgG and IgM are present
22 Cellular Immunity • T lymphocytes: • T Cytotoxic (Tc) cells • T Helper (Th) cells • Memory cells
23 Adaptive Immunity • Clonal diversity • Production of T and B lymphocytes • Antigen recognition • Lymphocyte specificity • Clonal selection • Antigen processing and presentation • Complex cellular interactions
24 Generation of Clonal Diversity • All necessary receptor specificities are produced • Takes place in the primary (central) lymphoid organs (thymus, bone marrow) • Results in immature but immunocompetent T and B cells • Primarily occurs in the fetus
25 Clonal Diversity • B Cell Development: • Production, proliferation, differentiation in bone marrow • Travel to lymphoid tissue and reside there as immunocompetent cells • Each cell responds to only one specific antigen
26 Clonal Diversity (cont’d) • T Cell Development: • The thymus is the central lymphoid organ of T cell development • Development of antigen-specific T cell receptors (TCRs) • Leave thymus, travel to and reside in lymphoid tissue as mature immunocompetent cells
27 Clonal Selection: Antigen Processing and Presentation • Initiated when T and B cells interact with an antigen • Must first be processed and then presented by antigen- processing (antigen-presenting) cells (APCs) • Results: • Differentiation of B cells into active antibody-producing cells (plasma cells) • Differentiation of T cells into effector cells, such as Tcytotoxic cells
28 Clonal Selection: Antigen Processing and Presentation (cont’d) • For processing and presentation to occur, the antigen must be of the appropriate type, the lymphocytes must be prepared to recognize the presented antigen, and the antigen must be presented appropriately
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- Spring '14