title: Antibodies to RNA polymerase III in systemic sclerosis detected by ELISA.
abstract: OBJECTIVE
  To determine serological and clinical variables associated with anti-RNA polymerase III (RNAP-III) antibodies in patients with systemic sclerosis (SSc) using a new ELISA method.
  
  
  METHODS
  Sera from 242 patients with SSc were collected from 14 Canadian clinics. Control sera were from 287 blood donors, and 42 patients with infectious disease, 30 with rheumatoid arthritis (RA), and 30 with systemic lupus erythematosus (SLE). Antibodies to RNAP-III were detected by an ELISA kit and antibodies to other cellular antigens were identified by indirect immunofluorescence (IIF) on HEp-2 cell substrate, line immunoassay, immunoprecipitation of recombinant protein, and addressable laser bead immunoassay (ALBIA).
  
  
  RESULTS
  Anti-RNAP-III antibodies were detected in 47/242 (19.4%) SSc sera, 0% RA and SLE sera, 1/287 blood donor sera, and 2/42 infectious disease sera. Diffuse disease (59.5%) was more common than limited disease (36.1%) in the anti-RNAP-III-positive patients (p = 0.006) and there was an association between the presence of anti-RNAP-III and kidney and joint/tendon involvement, but there was no association with a nucleolar IIF pattern, lung involvement, or other clinical indicators. There was a negative association between the presence of anti-RNAP-III antibodies and anticentromere by IIF (p = 0.00004) and anti-Scl-70 by ALBIA (p = 0.0005) and line immunoassay (p = 0.003), suggesting a virtually exclusive presence of these antibodies in SSc.
  
  
  CONCLUSIONS
  Anti-RNAP-III autoantibodies were found in nearly 20% of SSc patients but in less than 1% of controls, thus detection of this antibody is a useful marker to help diagnose SSc. As well, this antibody has prognostic utility, since it is associated with scleroderma renal crisis and the diffuse cutaneous form of SSc.
authors.affiliation: Serviço de Reumatologia do Hospital do Santa Izabel, Escola Bahiana de Medicina e Saúde Pública, Salvador, Brazil.
authors.forename: Mittermayer
authors.initials: M
authors.lastname: Santiago
authors.forename: Murray
authors.initials: M
authors.lastname: Baron
authors.forename: Marie
authors.initials: M
authors.lastname: Hudson
authors.forename: Rufus W
authors.initials: RW
authors.lastname: Burlingame
authors.forename: Marvin J
authors.initials: MJ
authors.lastname: Fritzler
mesh_terms: D000974:Antibodies, Antinuclear / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D012320:RNA Polymerase III / Q000276:immunology*; D012595:Scleroderma, Systemic / Q000097:blood* / Q000175:diagnosis / Q000503:physiopathology; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
chemical_list: D000974:Antibodies, Antinuclear; D012320:RNA Polymerase III