title: Polyclonal activation of xid B cells by auto-Ia-reactive T cell clones.
abstract: The mechanism of T cell-dependent activation of xid B cells into Ig-producing cells was studied by employing H-2-restricted, antigen-specific T cell clones. Helper factors (B cell stimulatory factors, BSF) released from KLH-specific T cell lines could induce polyclonal Ig production in B cells from (CBA/N X BALB/c)F1 (NBF1) female mice but not from CBA/N or NBF1 male mice. Direct addition of helper T cell lines induced Ig production in xid B cells from CBA/N or NBF1 male mice. A T cell clone, MK6, which was derived from NBF1 male mice and specific against Iad determinant, could activate NBF1 male but not CBA/N B cells. Another clone, CK4, derived from CBA/N mice and having specificity against KLH plus I-Ak determinant could activate both CBA/N and NBF1 male B cells into IgM- and IgG-producing cells in the absence of KLH, and monoclonal anti-I-Ak antibody specifically blocked such activation. These results suggest that xid B cells are able to be activated by the signal provided by the recognition of Ia molecules on B cells by auto-Ia-reactive T cells. Xid B cells from CBA/N mice that had been co-cultured with a T cell line specific against I-Ak determinant for 24 hr became reactive to BSF and capable of differentiating into Ig-producing cells in the presence of BSF. The results showed that even xid B cells could be responsive to BSF if they were in a certain activation stage.
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology; D001324:Autoantigens / Q000235:genetics / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D002999:Clone Cells / Q000276:immunology; D005260:Female; D006133:Growth Substances / Q000502:physiology; D006183:H-2 Antigens / Q000235:genetics; D006433:Hemocyanins; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D007136:Immunoglobulins / Q000096:biosynthesis; D007153:Immunologic Deficiency Syndromes / Q000235:genetics; D015847:Interleukin-4; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000502:physiology; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008807:Mice, Inbred BALB C; D008808:Mice, Inbred CBA; D008811:Mice, Inbred DBA; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000941:Antigens; D001324:Autoantigens; D006133:Growth Substances; D006183:H-2 Antigens; D000949:Histocompatibility Antigens Class II; D007136:Immunoglobulins; D008222:Lymphokines; D015847:Interleukin-4; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin