title: Concanavalin A supernatant recruits antigen-insensitive IgG memory B lymphocyte precursors into an antigen-sensitive precursor pool.
abstract: Spleen cells from mice primed to trinitrophenyl-keyhole limpet hemocyanin (TNP-KLH) generate IgG anti-TNP memory responses when stimulated in vitro with either thymus-dependent (TD) or thymus-independent (TI) forms of the hapten. When supernatants from Con A-stimulated spleen cells (Con A Sup) were added to such secondary cultures the TI responses to DNP-dextran or TNP-T4 were augmented; the TD response to TNP-KLH was suppressed. Passage over Sephadex and addition of alpha-methyl-D-mannoside did not inhibit augmentation by Con A Sup, indicating that augmentation did not result from direct action of the lectin on the responding cells. Augmentation occurred equally well in cultures that had been depleted of T cells by treatment with anti-Thy-1.2 and complement. Limiting dilution analyses revealed that Con A Sup increased the frequency of TI-responding precursors approximately threefold while causing a concomitant decrease in TD-responding precursors. To determine the relationship of the additional TI precursors and those normally detected in the absence of Con A Sup, the TI-responding IgG precursors were first eliminated through selective suicide by using DNP-dextran plus BUdR and light treatment; subsequently no TI-responding IgG PFC could be detected to DNP-dextran unless Con A Sup was also added. The data suggest Con A Sup may augment the TI responses to DNP-dextran and TNP-T4 by recruiting additional precursors from a memory cell pool formerly insensitive to these forms of antigen.
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology*; D000961:Antilymphocyte Serum / Q000494:pharmacology; D001402:B-Lymphocytes / Q000145:classification / Q000187:drug effects / Q000276:immunology*; D001973:Bromodeoxyuridine / Q000494:pharmacology; D003208:Concanavalin A / Q000494:pharmacology*; D003911:Dextrans / Q000276:immunology; D004136:Dinitrobenzenes / Q000276:immunology; D005260:Female; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000276:immunology*; D007156:Immunologic Memory; D008027:Light; D008766:Methylmannosides / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000941:Antigens; D000961:Antilymphocyte Serum; D003911:Dextrans; D004136:Dinitrobenzenes; D007074:Immunoglobulin G; D008766:Methylmannosides; D003208:Concanavalin A; D001973:Bromodeoxyuridine