Anti-cyclic citrullinated peptide and anti-keratin antibodies in patients with idiopathic inflammatory myopathy

Rheumatology (Oxford). 2009 Jun;48(6):676-9. doi: 10.1093/rheumatology/kep065. Epub 2009 Apr 22.


Objective: To investigate the prevalence of anti-cyclic citrullinated peptide (anti-CCP) and anti-keratin antibodies (AKAs) in a cohort of patients with idiopathic inflammatory myopathy.

Methods: In a cross-sectional study, we determined the presence of anti-CCP and AKAs by ELISA and IIF, respectively, in a cohort of 90 consecutive patients with idiopathic inflammatory myopathy. Associations between anti-CCP and clinical manifestations or other autoantibodies were determined with the chi-square and Mann-Whitney U-tests. Radiographs of hands were retrospectively evaluated. Serum autoantibody profile was determined in all patients.

Results: Twelve patients were positive to anti-CCP (13.3%); in eight cases values were moderate-high. AKAs were not detected in any patient. Comparison between patients positive and negative to anti-CCP did not show clinical or biological differences. Arthritis joint erosions or positive status to anti-synthetase antibodies were not more frequent in patients with anti-CCP antibodies. Prevalence of RF was the only variable significantly associated with the presence of these antibodies (P = 0.043).

Conclusions: High titres of anti-CCP can occasionally be found in patients with inflammatory myopathy. Therefore, a possible diagnosis of RA should be considered with caution in these patients.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Autoantibodies / blood*
  • Biological Factors / blood
  • Chi-Square Distribution
  • Cross-Sectional Studies
  • Enzyme-Linked Immunosorbent Assay
  • False Positive Reactions
  • Female
  • Fluorescent Antibody Technique, Indirect
  • Hand / diagnostic imaging
  • Humans
  • Keratins / immunology*
  • Male
  • Middle Aged
  • Myositis / diagnostic imaging
  • Myositis / immunology*
  • Peptides, Cyclic / immunology*
  • Radiography
  • Rheumatoid Factor / analysis
  • Statistics, Nonparametric


  • Autoantibodies
  • Biological Factors
  • Peptides, Cyclic
  • cyclic citrullinated peptide
  • Keratins
  • Rheumatoid Factor