Transcript Slide 1
Humoral Immunity presented by Dr. MAHROO MIRAHMADIAN Professor of Immunology Tehran University of Medical Sciences Antibodies Antibody Structure and function Protein electrophoresis Multiple Myeloma Antigen Binding Site Antibodies are Proteins that Recognize Specific Antigens Hypervariable regions Antibody is a flexible molecule Immunoglobulin Domain Ig Superfamily Proteolytic Digestion A MW of 150,000 Da A MW of 100,000 Da A MW of 25,000 Da A MW of 45,000 Da A MW of 50,000 Da A MW of 50,000 Da Proteolytic Digestion Antibody classes IgG subclasses Opsonization Complement activation Neutralization ADCC Effector functions of IgG Antibody Opsonization of bacteria for phagocytosis by macrophages and neutrophils Neutralization of toxins Activation of the classical pathway of complement Antibody dependent cell mediated cytotoxicity (ADCC) by NK cells. Neutralization of microbes Transfer of maternal antibody across the placenta and gut. Effector functions of IgG subclasses IgG1, IgG3 and IgG4 readily cross the placenta (neonatal immunity) IgG3, IgG1 are effective complement activator, and IgG4 is not able to activate complement. IgG1 and IgG3 bind to Fc receptors on phagocytic cells and thus mediate opsonization. sIgA Neutralization Effector functions of IgA antibody Mucosal immunity: secretion of IgA into the lumens of the gastrointestinal and respiratory tract. Neonatal immunity: transfer of maternal IgA from breast milk Neutralization of bacteria, viruses and toxins IgM Effector functions of IgM antibody Elevated level of IgM usually indicated either recent infection or recent exposure to the antigen. Isohemagglutinins. Antigen receptor of naive B lymphocyte. Activation of classical pathway of complement. IgM is the first antibody produced in a primary response to an antigen. Effector functions of IgD antibody IgD, together with IgM, is expressed by matureB cell IgE Allergen cross-linkage of receptor-bound IgE on mast cells induces degranulation Mast cells basophils and activated eosinophils bind IgE antibody via Fc eR Mast cells contain cytoplasmic granules that contain mixture of chemical mediators: histamine which make local blood vessels permeable. Lipid mediators such as prostaglandin D2 and leukotriene C4 and to secret cytokines such as TNF-a. ADCC Effector functions of IgE antibody IgE antibody mediate immediate hypersensitivity reaction. Antibody dependent cell mediated cytotoxicity (ADCC) involving eosinophils Isotype Allotype Idiotype Idiotype