title: Anti-cyclic citrullinated peptide and anti-keratin antibodies in patients with idiopathic inflammatory myopathy.
abstract: 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.
authors.affiliation: Internal Medicine Department, Vall d'Hebron General Hospital, Barcelona, Spain. mlabrador@vhebron.net
authors.forename: Moisés
authors.initials: M
authors.lastname: Labrador-Horrillo
authors.forename: Ma Angeles
authors.initials: MA
authors.lastname: Martinez
authors.forename: Albert
authors.initials: A
authors.lastname: Selva-O'Callaghan
authors.forename: Juan Francisco
authors.initials: JF
authors.lastname: Delgado
authors.forename: Xavier
authors.initials: X
authors.lastname: Martínez-Gómez
authors.forename: Ernesto
authors.initials: E
authors.lastname: Trallero-Araguás
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Rodriguez-Sanchez
authors.forename: Miquel
authors.initials: M
authors.lastname: Vilardell-Tarrés
mesh_terms: D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D001685:Biological Factors / Q000097:blood; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005189:False Positive Reactions; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006225:Hand / Q000000981:diagnostic imaging; D006801:Humans; D007633:Keratins / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D009220:Myositis / Q000000981:diagnostic imaging / Q000276:immunology*; D010456:Peptides, Cyclic / Q000276:immunology*; D011859:Radiography; D012217:Rheumatoid Factor / Q000032:analysis; D018709:Statistics, Nonparametric
chemical_list: D001323:Autoantibodies; D001685:Biological Factors; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D007633:Keratins; D012217:Rheumatoid Factor