title: Molecular characterization of the SM and RNP nuclear antigens.
abstract: Patients with systemic lupus erythematosus (SLE) often possess antibodies against two nuclear antigens, designated "Sm" and "RNP". The exact relationship between Sm and RNP is not clear; the present study was conducted to define these two different nuclear antigens. Rabbit thymus extracts were used to obtain purified Sm/RNP complex and free Sm antigens by using a combination of 25-60% ammonium sulfate precipitation, DEAE-Sephacel and hydroxylapatite chromatography. By using the separated antigens, sera characterized as anti-Sm, anti-Sm/RNP and anti-RNP could be distinguished by enzyme-linked immunosorbent assay (ELISA). Anti-Sm and/or anti-RNP antibodies were detected in 32 (52%) of 62 sera from patients with SLE. Of these 32, 6 contained anti-Sm only, 10 contained anti-RNP only and 16 had both. When HeLa nuclear extracts were used as antigens by immunoblotting, sera with anti-RNP reacted primarily with 2 polypeptides of 68 and 45 KD; sera with anti-Sm recognized mainly on 2 polypeptides of 26 and 14 KD; sera with anti-Sm/RNP recognized both groups. When purified Sm/RNP complex from rabbit thymus extracts was used as antigen by immunoblotting, sera with anti-RNP reacted with 68 KD protein and putative degradation products of the 68 KD protein. (major: 63 KD, 45 KD, 40 KD; minor: 54-47 KD); sera with anti-Sm recognized 14 KD protein; sera with anti-Sm/RNP reacted with both groups. Although Sm and RNP can exist as a Multimolecular complex, the epitopes recognized by anti-Sm and anti-RNP differ greatly. The Sm determinants reside primarily on proteins of 26 KD and 14 KD, whereas the RNP determinants reside mainly on a protein of 68 KD.
authors: Department of Internal Medicine, Chung Shan Medical & Dental College Hospital, Taichung, Taiwan.
authors: G J
authors: GJ
authors: Tsay
authors: M J
authors: MJ
authors: Chou
mesh_terms: D000818:Animals; D000906:Antibodies / Q000032:analysis; D001324:Autoantigens / Q000276:immunology; D006801:Humans; D015151:Immunoblotting; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D011817:Rabbits; D012261:Ribonucleoproteins / Q000032:analysis*; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins
chemical_list: D000906:Antibodies; D001324:Autoantigens; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins