中科院细胞与分子免疫学课程课件3+Antibodies+and+Antigensnew2.ppt

Section II Recognition of Antigens;;Section II Recognition of Antigens;Chapter 5 Antigen Processing and Presentation to T Lymphocytes Chapter 6 Antigen Receptors and Accessory Molecules of T Lymphocytes ;Chapter3 Antibodies and Antigens; Natural Distribution and Production of Antibodies;Binding antigen phase: ----In recognition phase - Membrane antibody function as BCR Na?ve B cell changed into activated phase ----In effector phase - Secreted form Eliminate the antigen;70-kg adult human : 3g of antibodies Two thirds of the antibody: IgA Antibodies that enter the circulation have limited half-lives. ----IgG, has a half-life of about 3 weeks.;Molecular Structure of Antibodies ;;Ig domain: about 110 amino acid residues fold independently in a globular motif Ig super-family: All molecules that contain this motif ; Both the heavy chains and light chains have: ----- N terminal variable regions in antigen recognition ------ C terminal constant regions in effector functions;Structural Features of Variable Regions and Their Relationship to Antigen Binding ;Crystallographic analyses of antigen-antibody complexes ;Complementarity-determining regions (CDRs): Region: The three hypervariable regions of a VL domain and VH domain are brought together in three-dimensional space to form an antigen-binding surface. Character: a surface complementary to the three-dimensional structure of the bound antigen; Structural Features of Constant Regions and Their Relationship to Effector Functions ;Isotypes: classes IgG - Gamma (?) heavy chainsγ IgM - Mu (?) heavy chains μ IgA - Alpha (?) heavy chains α IgD - Delta (?) heavy chains δ IgE - Epsilon (?) heavy chains ε ;Immunoglobulin Isotypes;Subtypes：In humans, IgA and IgG isotypes can be further subdivided into closely related subclasses, or subtypes, called IgA1 and IgA2, and IgG1, IgG2, IgG3, and IgG4. ;Immunoglobulin Allotypes（同种异型）;Immunoglobulin Idiotypes（独特型）;Antibody molecules