title: Molecular properties of the Ro/SSA antigen and enzyme-linked immunosorbent assay for quantitation of antibody.
abstract: Antibodies to the Ro/SSA antigen occur in patients with systemic lupus erythematosus and Sjögren's syndrome. An immunoaffinity method for the preparation of electrophoretically homogeneous Ro/SSA antigen is described. Several molecular properties of the antigen have been determined. The native RNA protein particle has a molecular weight of approximately 100,000 D determined by gel filtration. Sodium dodecyl sulfate-analysis of the purified Ro/SSA antigen and analysis by staining of bands with silver and Coomassie Blue, Western blotting, and RNAase treatment leads to a hypothesis for the structure of the particle in which an antigenic 60,000 protein is bound to 24,000-27,000 RNA molecules which are not antigenic. An enzyme-linked immunoabsorbent assay method for assay of anti-Ro/SSA is also described which sensitively measures antigen binding at dilutions of sera containing anti-Ro/SSA precipitins up to 10(7) fold. Normal sera on average have 10(3) less binding activity.
mesh_terms: D000818:Animals; D000936:Antigen-Antibody Complex; D000941:Antigens / Q000276:immunology*; D001323:Autoantibodies / Q000032:analysis*; D001324:Autoantigens; D002417:Cattle; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D008214:Lymphocytes / Q000276:immunology*; D008970:Molecular Weight; D020733:RNA, Small Cytoplasmic; D012016:Reference Values; D012261:Ribonucleoproteins; D013154:Spleen / Q000276:immunology; D013950:Thymus Gland / Q000276:immunology*; D000099207:SS-A Antigen
chemical_list: D000936:Antigen-Antibody Complex; D000941:Antigens; D001323:Autoantibodies; D001324:Autoantigens; D020733:RNA, Small Cytoplasmic; D012261:Ribonucleoproteins; D000099207:SS-A Antigen; C116006:RO60 protein, human