title: B lymphocyte activation upon exclusive recognition of major histocompatibility antigens by T helper cells.
abstract: This study has investigated whether exclusive recognition of I-A or I-E molecules on the B cell surface by T helper cells is sufficient to activate resting B cells. Lines and clones of long-term-cultured T helper cells with specificity for I-A or I-E antigens have been derived from mixed lymphocyte cultures between spleen cells from major histocompatibility complex (MHC)-congenic mouse strains. These cells were tested for helper activity and proved competent to induce resting B lymphocytes expressing the specific MHC antigens to polyclonal expansion and maturation to Ig secretion. B cell activation was shown to require direct recognition of I-A/E antigens by the helper cells on the responding B lymphocyte surface and it could not be achieved by soluble factors released by "third-party" helper cell activity ongoing in the same cultures. Since B lymphocyte activation occurs in the absence of antigen recognition by the responding B cells, these observations suggest that I-A and I-E molecules expressed on the B cell surface participate in the functional reception of T helper cell-derived induction signals.
mesh_terms: D000818:Animals; D000921:Antibody-Producing Cells / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D002999:Clone Cells / Q000276:immunology; D000939:Epitopes; D006462:Hemolytic Plaque Technique; D006649:Histocompatibility Antigens / Q000235:genetics / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000276:immunology*; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D051379:Mice; D008810:Mice, Inbred C57BL; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
chemical_list: D000939:Epitopes; D006649:Histocompatibility Antigens; D000949:Histocompatibility Antigens Class II; C024138:I-E-antigen