title: Sequential requirements for cell cycle progression of resting human B cells after activation by anti-Ig.
abstract: We have previously demonstrated that in vivo activated normal human B cells reflected differential sensitivity on the basis of cell size to either an activation signal delivered by anti-mu or a proliferative signal delivered by a monoclonal B cell growth factor (BCGF) produced by a human T-T hybridoma. In this manuscript, we have shown that by using an in vitro co-culture system of stimulation with anti-mu and BCGF, purified small (resting) B cells could be induced by anti-mu stimulation to express functionally active BCGF acceptor sites concomitant with RNA synthesis and cell enlargement. We have demonstrated that purified small B cells could be activated to increase both cell size and RNA synthesis within 8 hr of anti-mu stimulation. DNA synthesis by anti-mu-stimulated B cells began at 36 to 44 hr from initial stimulation only when BCGF was added to the culture. In addition, large B cells that had been incubated with anti-mu for 24 to 48 hr manifested significant incorporation of [3H]thymidine if BCGF was added to cultures. These data strongly suggest that anti-mu may induce the G0 phase B cells into the G1 phase and that BCGF may then push at least a subset of these G1 phase-B cells into the S phase. This experimental system may provide a useful model of normal human B cell activation and proliferation and may allow a more precise delineation of each phase of this cascade in the B cell repertoire.
mesh_terms: D000293:Adolescent; D000328:Adult; D000888:Antibodies, Anti-Idiotypic / Q000502:physiology*; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology; D002453:Cell Cycle; D002648:Child; D004247:DNA / Q000096:biosynthesis; D006133:Growth Substances / Q000502:physiology; D006801:Humans; D007148:Immunoglobulin mu-Chains / Q000276:immunology; D015847:Interleukin-4; D007700:Kinetics; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000502:physiology; D012313:RNA / Q000096:biosynthesis
chemical_list: D000888:Antibodies, Anti-Idiotypic; D006133:Growth Substances; D007148:Immunoglobulin mu-Chains; D008222:Lymphokines; D015847:Interleukin-4; D012313:RNA; D004247:DNA