title: Characterization of a B cell defect in the NZB mouse manifested by an increased ratio of surface IgM to IgD.
abstract: In an effort to define the cellular basis of abnormalities in polyclonal B cell activation previously noted in NZB mice, the surface immunoglobulin (sIg) isotypes of spleen cells from NZB mice were examined. After lactoperoxidase-catalyzed radioiodination, the cell surface immunoglobulins were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Spleen cells from 8- to 10-week-old NZB mice were found to have an increased ratio of cell surface IgM/IgD compared to cells from 11 control strains. The altered ratio of sIg isotypes was not a consequence of increased proteolytic activity present in NZB cell suspensions or of the presence of cytophilic antibody or autoantibody. Ontogenetic studies of the sIgM/sIgD (mu/delta) ration on splenocytes from NZB and BALB/c mice revealed that the former cells had higher mu/delta ratios as early as 2 weeks after birth. By 4 weeks of age the mu/delta ratios were equivalent. Between 4 weeks and 1 year of age, the mu/delta ratios on NZB splenocytes remained constant whereas those on BALB/c splenocytes decreased and reached adult levels at 6 weeks.
mesh_terms: D000818:Animals; D001323:Autoantibodies; D001402:B-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D007072:Immunoglobulin D; D007075:Immunoglobulin M; D007457:Iodine Radioisotopes; D008198:Lymph Nodes / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008814:Mice, Inbred NZB; D010447:Peptide Hydrolases / Q000494:pharmacology; D011947:Receptors, Antigen, B-Cell; D013154:Spleen / Q000276:immunology
chemical_list: D001323:Autoantibodies; D007072:Immunoglobulin D; D007075:Immunoglobulin M; D007457:Iodine Radioisotopes; D011947:Receptors, Antigen, B-Cell; D010447:Peptide Hydrolases