title: Role of antigen in the B cell response. Specific antigen and the lymphokine IL-5 synergize to drive B cell lymphoma proliferation and differentiation to Ig secretion.
abstract: CH12 tumor B cells specific for SRBC require SRBC as Ag and the lymphokine IL-5 (formerly known as BCGFII) for optimal proliferation and differentiation to Ig-secreting cells. Lysed SRBC and IL-5 purified to homogeneity synergize markedly, especially at low B cell densities. A sizable proportion of CH12 cells differentiate into Ig-secreting plaque-forming cells when low numbers of the B lymphoma cells (100 to 3000) are cultured with Ag and IL-5. IL-2 or IL-4 have no effects. Intact SRBC or lysed SRBC are equally effective as sources of Ag. Even in the presence of the mitogens LPS and dextran sulfate, there is a striking requirement for Ag for both proliferation and differentiation at low B cell density. Because of the low cell numbers used, the results strongly suggest that the effects of Ag and lymphokine are directly on the B cell. The cell surface phenotype of the CH12 lymphoma and the kinetics of their response suggest that CH12 B cells have the characteristics of activated B cells. Thus, it appears that Ag binding to surface Ig gives a direct signal to at least some B cells that is critical in the later phases of the B cell response after initial activation during which proliferation and differentiation to Ig secretion occur and that the lymphokine IL-5 costimulates with Ag to mediate this phase of the response.
mesh_terms: D000276:Adjuvants, Immunologic / Q000502:physiology*; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D001789:Blood Group Antigens / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects; D002458:Cell Fractionation; D002460:Cell Line; D016264:Dextran Sulfate; D003911:Dextrans / Q000494:pharmacology; D007136:Immunoglobulins / Q000096:biosynthesis*; D015848:Interleukin-5; D007378:Interleukins / Q000502:physiology*; D007958:Leukocyte Count; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D008223:Lymphoma / Q000276:immunology / Q000473:pathology; D051379:Mice; D012756:Sheep
chemical_list: D000276:Adjuvants, Immunologic; D001789:Blood Group Antigens; D003911:Dextrans; D007136:Immunoglobulins; D015848:Interleukin-5; D007378:Interleukins; D008070:Lipopolysaccharides; D016264:Dextran Sulfate