title: Frequency analysis of functional immunoglobulin C and V gene expression in murine B cells at various ages.
abstract: The frequencies of lipopolysaccharide- (LPS) reactive B cells and their antibody specificity repertoire have been determined in the spleen and bone marrow (BM) of mice at different ages. A limiting dilution culture system was employed that allows the growth and development of every LPS-reactive B cell into a clone an IgM-secreting cells that are capable of switching to other Ig heavy chain isotypes (C gene expression). The secretion of IgM and IgG1 was assessed in the protein A plaque assay, whereas specific IgM antibody-secreting cells (V gene expression) were detected with the use of plaque assays specific for various heterologous erythrocytes and sheep red blood cells (SRBC) coupled with a number of different haptens. The frequencies of LPS-reactive B cells in the spleen and BM of C3H/Tif, C57BL/Ka, BALB/c, and CBA/Rij mice appeared to be similar in 6- to 12- and 100-wk-old animals, as was the switch frequency to IgG1 secretion in three strains tested. Moreover, no age-related changes were observed in the frequencies of antigen-specific B cells within the pool of LPS-reactive B cells in the spleen and BM of C57BL/Ka mice. The frequencies ranged from 1 in 10 to 1 in 20 for NIP4- and NNP2-SRBC, from 1 in 50 to 1 in 100 for TNP30-SRBC, and from 1 in 1000 to 1 in 4000 for SRBC, HRBC, and GRBC. The specificity repertoire of the "spontaneously" occurring ("background") IgM-secreting cells in the spleen and BM, on the other hand, did differ between young and old C57BL/Ka mice. During aging the frequencies of the tested specificities decreased in the spleen but increased in the BM. Our data indicate that in unintentionally immunized mice the clonal selection of B lineage cells by antigen takes place at the level of the mature, antigen-reactive B cell.
mesh_terms: D000375:Aging; D000818:Animals; D000918:Antibody Specificity; D000921:Antibody-Producing Cells / Q000276:immunology / Q000502:physiology; D001402:B-Lymphocytes / Q000276:immunology* / Q000502:physiology; D001854:Bone Marrow Cells; D002452:Cell Count; D005260:Female; D007127:Immunoglobulin Constant Regions / Q000235:genetics* / Q000276:immunology; D007074:Immunoglobulin G / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000096:biosynthesis; D007135:Immunoglobulin Variable Region / Q000235:genetics* / Q000276:immunology; D007136:Immunoglobulins / Q000235:genetics*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D051381:Rats; D011917:Rats, Inbred Lew; D013154:Spleen / Q000166:cytology
chemical_list: D007127:Immunoglobulin Constant Regions; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007135:Immunoglobulin Variable Region; D007136:Immunoglobulins; D008070:Lipopolysaccharides