title: Anti-cyclic citrullinated peptide antibody in systemic sclerosis.
abstract: OBJECTIVE
  To determine if anti-cyclic citrullinated peptide (anti-CCP) antibody titers can distinguish the overlap syndrome of systemic sclerosis and rheumatoid arthritis (SSc-RA) in patients with systemic sclerosis (SSc) and to investigate the clinical significance of anti-CCP antibodies in SSc.
  
  
  METHODS
  Serum levels of anti-CCP antibodies were measured by enzyme-linked immunosorbent assay in 159 outpatients: 114 with SSc, 14 with rheumatoid arthritis, 7 with SSc-RA overlap syndrome, and 24 with Sjögren's syndrome. In patients with SSc and SSc-RA, we also measured serum levels of matrix metalloproteinase-3 and anti-agalactosyl IgG antibody.
  
  
  RESULTS
  Elevated serum levels of anti-CCP antibodies were observed in 3 of 114 patients (2.6%) with SSc, 9 of 14 patients (64%) with RA, 6 of 7 patients (86%) with SSc-RA, and only 1 of 24 patients (4.2%) with SjS. In patients with SSc-RA, serum anti-CCP antibody levels were significantly higher than those seen in SSc (p<0.001). The sensitivity, specificity, and predictive values of elevated anti-CCP titers for SSc-RA were higher than either matrix metalloproteinase-3 and anti-agalactosyl IgG antibodies as markers. In addition, almost all SSc-RA and SSc patients with elevated serum levels of anti-CCP antibodies exhibited arthralgias and interstitial pneumonia.
  
  
  CONCLUSIONS
  Anti-CCP antibody titers are a reliable marker of SSc-RA facilitating its distinction from SSc alone.
authors.affiliation: Division of Connective Tissue Disease & Autoimmunity, Department of Dermatology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Morita
authors.forename: Y
authors.initials: Y
authors.lastname: Muro
authors.forename: K
authors.initials: K
authors.lastname: Sugiura
authors.forename: Y
authors.initials: Y
authors.lastname: Tomita
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000175:diagnosis* / Q000276:immunology; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology*; D012217:Rheumatoid Factor / Q000097:blood; D012595:Scleroderma, Systemic / Q000175:diagnosis / Q000276:immunology*; D013577:Syndrome; D055815:Young Adult
chemical_list: D001323:Autoantibodies; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D012217:Rheumatoid Factor