title: Frequency analysis of immunoglobulin V-gene expression and functional reactivities in bone marrow B cells.
abstract: Frequency of immunocompetent B cells in bone marrow has been determined in vitro under culture conditions that allow the development in vitro under culture conditions that allow the development of every growth-inducible B cell into a clone of IgM-secreting PFC. Three limiting dilution culture systems were employed: a specific helper assay with SRBC as antigen and using activated T helper cells, a nonspecific helper assay using Con A-induced factors as a source of help, and polyclonal activation with LPS. From unseparated, normal C57BL/6J bone marrow 1 in 2200 to 1 in 2820 B cells were induced to form a clone of PFC to SRBC in each of the 3 systems. This corresponds to a frequency of 1 SRBC-specific clone in every 900 IgM-secreting LPS-reactive clones. The frequencies of specific plaque-forming B cell clones in terms of LPS-reactive B cells was 1 in 36 for NNP1-SRBC, 1 in 58 for TNP30-SRBC, 1 in 75 for NIP1-SRBC, and 1 in 230 for TNP3-SRBC. These frequencies of v-gene expression in bone marrow B cells are of the same magnitude as the corresponding frequencies for splenic B cells. Bone marrow B cells are also fully susceptible to stimulation by antigen in combination with either specific or nonspecific T cell help, as well as polyclonal activation by LPS, since every 3rd Ig-positive cells in marrow could be induced to form a clone of IgM-secreting cells. There is thus no difference in immunocompetence between surface Ig-bearing B cells from bone marrow and spleen.
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D001402:B-Lymphocytes / Q000276:immunology*; D001854:Bone Marrow Cells; D004136:Dinitrobenzenes / Q000276:immunology; D005260:Female; D005787:Gene Frequency; D007136:Immunoglobulins / Q000235:genetics*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D011917:Rats, Inbred Lew; D012756:Sheep; D014301:Trinitrobenzenes / Q000276:immunology
chemical_list: D004136:Dinitrobenzenes; D007136:Immunoglobulins; D008070:Lipopolysaccharides; D014301:Trinitrobenzenes