Cross-reactive responses Similar or identical antigenic determinants are sometimes found in association with widely different molecules or cells. This cross-reactivity is important: (a) in protection against organisms with cross-reactive antigens; and (b)in autoimmune diseases induced by infectious organisms bearing antigens cross-reactive with normal self antigens (e.g. streptococcal infections which predispose to rheumatic fever) Key notes
Similar or identical antigenic determinants are sometimes found in association with widely different molecules or cells. This cross-reactivity is important: (a) in protection against organisms with cross-reactive antigens; and (b) in autoimmune diseases induced by infectious organisms bearing antigens cross-reactive with normal self antigens (e.g. streptococcal infections which predispose to rheumatic fever). Cross-reactive responses Key notes
1. Selection and activation of b cells When antigen is introduced into an individual B cells with receptors for that antigen bind and internalize it into an endosomal compartment, and process and present it on MHc class ll molecules to helper T cells
1. Selection and activation of B cells When antigen is introduced into an individual, B cells with receptors for that antigen bind and internalize it into an endosomal compartment, and process and present it on MHC class II molecules to helper T cells
Processed antigen B cell MHC class Peptide derived from carrier protein presented i MHC class重 h
MHC class Peptide derived from carrier protein presented in MHC class Ⅱ
Selection and activation of b cells These B cells are triggered to proliferate, giving rise to clones of large numbers of daughter cells Some of the cells of these expanding clones serve as memory cells, others differentiate and become plasma cells which make and secrete large quantities of specific antibody
Selection and activation of B cells These B cells are triggered to proliferate, giving rise to clones of large numbers of daughter cells. Some of the cells of these expanding clones serve as memory cells, others differentiate and become plasma cells which make and secrete large quantities of specific antibody
活化B细胞 浆细胞 免疫球蛋白 (Activated b cell (plasma cell)( Immunoglobulin g
免疫球蛋白 （Immunoglobulin Ig） 活化B细胞 （Activated B cell） 浆细胞 (plasma cell)