title: Serum-mediated suppression of nonspecific B cell activation. II. Relative resistance of B cells from the NZB mouse strain to regulation by a natural inhibitor in normal mouse serum.
abstract: Recent work has shown that normal mouse serum (NMS) and plasma contain inhibitory substance(s), termed NMS-In, that suppress proliferative and polyclonal antibody responses elicited in vitro with various B cell mitogens. In this study, the NZB mouse, which has a high degree of spontaneous polyclonal B cell activity, was examined for possible reduced amounts of NMS-In. Also, the capacity of NZB B cells to be inhibited by NMS-In was determined. It was found that sera from NZB mice had normal amounts of NMS-In, as assessed by inhibition of mitogenesis of spleen cells in culture induced by bacterial endotoxin (ET). However, B cells of the NZB mouse were found to be abnormal, requiring approximately 4 to 7 times more NMS-In to inhibit polyclonal antibody synthesis and mitogenesis elicited by ET than B cells of more immunologically normal mice. Removal of T cells by treatment with anti-thy 1.2 and complement did not change the sensitivity of the NZB B cells to NMS-In. Insensitivity to NMS-In was expressed in B cells from relatively young NZB mice, e.g., 9 to 15 wk of age. The relative resistance of B cells of the NZB mouse to regulation by a natural inhibitor in NMS could partially serve to explain their high level of spontaneous antibody synthesis. Furthermore, the fact that B cells of the NZB mouse were ultimately susceptible to inhibition by relatively large amounts of NMS-In affords the opportunity in the future to suppress polyclonal antibody activity in the NZB mouse with purified NMS-In in an attempt to ameliorate autoimmune disease.
mesh_terms: D000818:Animals; D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology*; D004731:Endotoxins / Q000494:pharmacology; D007165:Immunosuppression Therapy; D008213:Lymphocyte Activation; D008212:Lymphocyte Depletion; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008814:Mice, Inbred NZB; D008934:Mitogens / Q000494:pharmacology; D013154:Spleen / Q000276:immunology
chemical_list: D004731:Endotoxins; D008934:Mitogens