title: Immunoglobulin isotype expression. II. Frequency analysis in mitogen-reactive B cells.
abstract: The frequency of lipopolysaccharide (LPS)-reactive B cells developing into clones that secrete the various immunoglobulin (Ig) classes has been determined in vitro, in cells from BALB/c mice, under culture conditions which detect all growth-inducible cells. Secretion of the different Ig classes was assessed in the protein A plaque assay for Ig-secreting, plaque-forming cells by using developing antisera specific for either IgM, IgG1, IgG2a, IgG2b, IgG3 or IgA. In all lymphoid organs tested (spleen, bone marrow, mesenteric lymph nodes and thoracic duct), a considerable proportion of all B cells (5-20%) was induced by LPS to yield a clone of IgM-secreting cells. Frequency determinations of LPS-reactive cells giving rise to descendants secreting other Ig isotypes revealed that, on an average, and irrespective of the origin of the cells, 7% of all IgM-secreting clones switched to the synthesis of IgG1, 39% to IgG2, 41% to IgG3 and 1% to IgA. Roughly the same frequencies of B cells switching CH gene expression were found among spleen cells of athymic nude mice. No correlation was found between the clonal frequencies of CH gene expression in polyclonally activated B cells and the in vivo "background" Ig-secreting cells suggesting that the CH gene expression in B cells is influenced by the quality of stimulation and other regulating influences.
mesh_terms: D000818:Animals; D000921:Antibody-Producing Cells / Q000378:metabolism; D001402:B-Lymphocytes / Q000166:cytology*; D002999:Clone Cells / Q000276:immunology; D005260:Female; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007136:Immunoglobulins / Q000145:classification*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D011817:Rabbits; D051381:Rats; D011917:Rats, Inbred Lew; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013897:Thoracic Duct / Q000166:cytology / Q000276:immunology
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007136:Immunoglobulins; D008070:Lipopolysaccharides