title: Lupus/Sjögren's autoantibody specificities in sera with paraproteins.
abstract: Antinuclear antibody and anti-RNA-protein autoantibodies were determined in 143 sera containing paraproteins and 39 control sera. Antinuclear antibodies were commonly present in the paraprotein sera by indirect immunofluorescence. 19 of 143 sera (13%) had elevated anti-Ro/SSA activity in a solid phase Ro/SSA binding assay, and 5 (3.5%) had Ro/SSA precipitating autoantibody. Eighteen sera had La/SSB binding autoantibodies (12%) but only one had an anti-La/SSB precipitin. Anti-nRNP(Sm) was not detected in any of these sera. The solid phase anti-RNA protein assays were repeated using anti-lambda and anti-kappa conjugates. Both lambda and kappa light chain autoantibodies were found in all positive sera consistent with polyclonal anti-Ro/SSA and anti-La/SSB responses. Paraprotein sera containing Ro/SSA precipitins were analyzed by isoelectric focusing followed by exposure to 125I-labeled Ro/SSA and autoradiography. All sera with anti-Ro/SSA binding paraproteins also contained polyclonal anti-Ro/SSA. Our data are consistent with the hypothesis that anti-Ro/SSA paraproteins are common and arise from a previously present polyclonal anti-Ro/SSA response.
mesh_terms: D000974:Antibodies, Antinuclear / Q000276:immunology; D000918:Antibody Specificity; D001323:Autoantibodies / Q000032:analysis / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology; D001327:Autoimmune Diseases / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D010266:Paraproteins / Q000276:immunology*; D020733:RNA, Small Cytoplasmic; D012261:Ribonucleoproteins; D012859:Sjogren's Syndrome / Q000276:immunology*; D055517:snRNP Core Proteins; D000097585:SS-B Antigen; D000099207:SS-A Antigen
chemical_list: D000974:Antibodies, Antinuclear; D001323:Autoantibodies; D001324:Autoantigens; D010266:Paraproteins; D020733:RNA, Small Cytoplasmic; D012261:Ribonucleoproteins; D055517:snRNP Core Proteins; D000097585:SS-B Antigen; D000099207:SS-A Antigen; C116006:RO60 protein, human