title: T-independent and T-dependent steps in the murine B cell response to antiimmunoglobulin.
abstract: Sepharose-anti-Ig and purified populations of small, high-density B cells have been used to study the formation and function of B lymphoblasts. Sepharose-anti-Ig converts small, Ia-poor B cells with a high-buoyant density to large, Ia-rich, B blasts with a low-buoyant density. We find that this response proceeds efficiently in the absence of IL-4 (BSF-1) as well as most T cells, macrophages, and dendritic cells. Further development of the blasts requires an additional stimulus, such as LPS or the conditioned medium of stimulated EL-4 thymoma cells. Within 6 h, blasts begin to enter S phase and within 24 h most divide. At later times (48-72 h) most of the blasts are actively secreting IgM. Recombinant IL-1, -2, -3, and -4 have little or no effect on the B blasts, and a neutralizing mAb to IL-4 does not block the response to EL-4 Sn. We conclude that Sepharose-anti-Ig induces B cell blastogenesis in a T-independent fashion and that these blasts represent a highly enriched population of cells that respond to distinct, T cell-derived lymphokines.
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000494:pharmacology*; D000911:Antibodies, Monoclonal; D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology; D002455:Cell Division; D005260:Female; D006133:Growth Substances / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D015847:Interleukin-4; D008222:Lymphokines / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D006133:Growth Substances; D007375:Interleukin-1; D008222:Lymphokines; D015847:Interleukin-4