title: Subclass restriction of anti-Sm antibodies in MRL mice.
abstract: The subclass distribution of anti-Sm antibodies in the serum of MRL/Mp-Ipr/Ipr and MRL/Mp- +/+ mice was investigated with a sensitive ELISA technique. In both strains, but particularly in the Ipr mice, anti-Sm antibodies were predominantly of the IgG2a isotype. This preponderance was not an artifact of the sensitivity or specificity of the subclass-specific anti-Sm ELISA, nor did it reflect the subclass distribution of total serum IgG. A plaque-forming cell assay for anti-Sm antibodies also showed a predominance of the IgG2a isotype, indicating that the serum findings could not be explained by differential catabolism of IgG subclasses. Finally, antibodies to double-stranded DNA, as detected by the Crithidia luciliae assay, did not show a restricted subclass distribution. The isotype expression of anti-Sm antibodies in MRL mice must reflect in vivo mechanisms regulating the production of these autoantibodies. The IgG2a restriction in particular suggests an important in vivo role for T cells.
mesh_terms: D000818:Animals; D000921:Antibody-Producing Cells / Q000276:immunology; D000941:Antigens / Q000276:immunology*; D001323:Autoantibodies / Q000145:classification / Q000235:genetics* / Q000276:immunology; D001324:Autoantigens; D001666:Binding Sites, Antibody; D004247:DNA / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D006462:Hemolytic Plaque Technique; D007074:Immunoglobulin G / Q000276:immunology; D051379:Mice; D008815:Mice, Inbred Strains / Q000276:immunology*; D011817:Rabbits; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins
chemical_list: D000941:Antigens; D001323:Autoantibodies; D001324:Autoantigens; D007074:Immunoglobulin G; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins; D004247:DNA