title: Use of a molecularly cloned human SS.B antigen to detect anti-SS.B antibodies.
abstract: The aim of this study was to examine the utility of diagnostic assays based on recombinant SS.B/La (rSS.B). Using this antigen, we have developed an ELISA and an immunoblot and compared these recombinant antigen-based assays with traditional thymus extract-based counterimmunoelectrophoresis (CIEP). Using the recombinant ELISA, the incidence of anti-SS.B in 184 normal blood donors was 2.2% (four sera). These four sera were all low titre, i.e., 3-5 SD above the mean. Of 38 sera positive for anti-SS.B by CIEP, 37 were positive in both recombinant assays (97.4% concordance). Anti-SS.B titre in CIEP correlated strongly with results of the rSS.B-based ELISA, but the ELISA was 3,000-fold more sensitive. In an analysis of 152 autoimmune sera containing anti-DNA, anti-RNP, anti-centromere, anti-SS.A/Ro or anti-cardiolipin, all of which were negative for anti-SS.B/La by CIEP, the recombinant assays detected 17 new anti-SS.B positives. These positive results were found only in sera which had previously been characterised by CIEP as anti-SS.A/Ro positive. Anti-SS.B/La antibodies detected by recombinant SS.B assays were found to be highly predictive of primary Sjögren's syndrome. Our results show that rSS.B can have an important role in the design of sensitive and specific assays for anti-SS.B. The diagnostic significance of anti-SS.B/La as a guide to primary Sjögren's syndrome is not diminished by the increased sensitivity of recombinant SS.B assays.
authors.affiliation: Dept. of Rheumatology, St George Hospital, New South Wales, Australia.
authors.forename: R A
authors.initials: RA
authors.lastname: Owe-Young
authors.forename: S
authors.initials: S
authors.lastname: Horn
authors.forename: J P
authors.initials: JP
authors.lastname: Edmonds
authors.forename: A D
authors.initials: AD
authors.lastname: Sturgess
mesh_terms: D000974:Antibodies, Antinuclear / Q000032:analysis; D001323:Autoantibodies / Q000032:analysis* / Q000276:immunology; D001324:Autoantigens / Q000235:genetics / Q000276:immunology*; D001327:Autoimmune Diseases / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D015415:Biomarkers; D001782:Blood Donors; D015153:Blotting, Western; D003378:Counterimmunoelectrophoresis; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D011993:Recombinant Fusion Proteins / Q000276:immunology*; D012016:Reference Values; D012261:Ribonucleoproteins / Q000235:genetics / Q000276:immunology*; D012680:Sensitivity and Specificity; D012859:Sjogren's Syndrome / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D000097585:SS-B Antigen
chemical_list: D000974:Antibodies, Antinuclear; D001323:Autoantibodies; D001324:Autoantigens; D015415:Biomarkers; D011993:Recombinant Fusion Proteins; D012261:Ribonucleoproteins; D000097585:SS-B Antigen