title: Triggering of affinity-enriched B cells. Analysis of B cell stimulation by antigen-specific helper factor or lipopolysaccharide. I. Dissection into proliferative and differentiative signals.
abstract: Proliferative and differentiative signals controlling the in vitro IgM response by unprimed, affinity-enriched B cells were studied using conditions under which as few as 2,000 B cells stimulated by antigen-specific, Ia-positive, allogeneically restricted, T cell-derived helper factor (Hf) or the polyclonal activator lipopolysaccharide (LPS) yielded on the average 400 antibody-forming cells (AFC) by direct plaque assay. Antigen alone induces neither B cell proliferation nor differentiation into AFC. Proliferation but not differentiation into AFC is induced when affinity-enriched B cells are cultured in the presence of Ag and Hf or LPS but in the absence of nonantigen-specific, radioresistant, accessory (A) cells. For the induction of a complete Hf- or LPS-mediated AFC response, cultures must be reconstituted with A cells or the secretory product(s) of these cells. The antigen-specific response depends strictly on the presence of the Hf specific for the relevant antigen, regardless of the cell cycle state of cooperating B cells. The differentiative signal from A cells is due, at least in part, to the presence of a Thy-1.2-bearing population of cells. In the case of the LPS-mediated, but not the Hf-mediated response. A cells can be substituted by using supernatant derived from an interleukin 2-secreting T lymphoma cell line (EL4). In the presence of histocompatible Hf and B cells, histoincompatible A cells can still cooperate in the immune response. However, the degree of allogeneic restriction between incompatible Hf and B cells is markedly increased if both B cells and A cells are incompatible with Hf.
mesh_terms: D000818:Animals; D000921:Antibody-Producing Cells / Q000276:immunology; D000961:Antilymphocyte Serum / Q000494:pharmacology; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002448:Cell Adhesion; D002454:Cell Differentiation; D002645:Chickens; D000939:Epitopes; D005260:Female; D007075:Immunoglobulin M / Q000096:biosynthesis; D007375:Interleukin-1; D007376:Interleukin-2 / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008213:Lymphocyte Activation; D008223:Lymphoma / Q000276:immunology; D008285:Major Histocompatibility Complex; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008808:Mice, Inbred CBA; D011506:Proteins / Q000494:pharmacology*; D012397:Rosette Formation; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000961:Antilymphocyte Serum; D000939:Epitopes; D007075:Immunoglobulin M; D007375:Interleukin-1; D007376:Interleukin-2; D008070:Lipopolysaccharides; D011506:Proteins