title: Identification of a major 50-kDa molecular weight human B-cell growth factor with Tac antigen-inducing activity on B cells.
abstract: A bioassay was developed using human small B cells adherent to anti-human IgM (anti-mu)-coated wells. These B cells were stimulated to proliferate by culture supernatants of concanavalin A (Con A)-activated human peripheral blood lymphocytes (Con A Sup) even in the presence of high concentrations of anti-mu coated on assay wells. Human B-cell growth factor (BCGF) activities were partially purified from Con A Sup. Preparative chromatography (Sephacryl S-200 and isoelectrofocusing) yielded a major peak of BCGF activity for B cells adherent to anti-mu-coated wells with a molecular weight of 50,000 (50 kDa) and a pI 7.6. The 50-kDa BCGF was further purified by sequential chromatography using DEAE-Sephacel, CM-Sepharose, Sephacryl S-200, CM-high performance liquid chromatography (HPLC), and hydroxyapatite (HA)-HPLC. The HA-HPLC-purified 50-kDa BCGF was free of interleukin-1 (IL-1), interleukin-2 (IL-2), and interferon activities, but could support growth of BCL1 cells, similar to BCGF-II. Neither IL-1 nor interferon-gamma had any growth-stimulating effect in our B-cell proliferation assay with or without BCGF in Iscove's synthetic assay medium. BCGF-induced proliferation of B cells adherent to anti-mu-coated wells could be markedly augmented by the simultaneous or sequential addition of recombinant human IL-2 (rIL-2). When cultured for 3 days with 50-kDa BCGF, about 40% of B cells adherent to anti-mu-coated wells expressed Tac antigen, and monoclonal anti-Tac antibody inhibited rIL-2 enhancement of proliferation of 50-kDa BCGF-preactivated B cells. In addition, 50-kDa BCGF could induce Tac antigen on an Epstein-Barr virus-transformed B-cell line (ORSON) in the presence of a suboptimal dose of phorbol myristate acetate (PMA) and also on a natural killer-like cell line (YT cells). We have therefore identified a major 50-kDa BCGF activity with Tac antigen-inducing activity that also has a synergistic effect with IL-2 on normal B-cell proliferation.
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D001402:B-Lymphocytes / Q000032:analysis* / Q000187:drug effects / Q000276:immunology; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology; D004357:Drug Synergism; D006133:Growth Substances / Q000302:isolation & purification*; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology; D007376:Interleukin-2 / Q000494:pharmacology; D015847:Interleukin-4; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D008222:Lymphokines / Q000302:isolation & purification* / Q000494:pharmacology; D051379:Mice; D011971:Receptors, Immunologic / Q000096:biosynthesis; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000888:Antibodies, Anti-Idiotypic; D006133:Growth Substances; D007075:Immunoglobulin M; D007376:Interleukin-2; D008222:Lymphokines; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins; C044203:anti-IgM; D003208:Concanavalin A; D015847:Interleukin-4