Anti-cyclic citrullinated peptide and anti-keratin antibodies in patients with idiopathic inflammatory myopathy.
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.
Labrador-Horrillo
Moisés
M
Internal Medicine Department, Vall d'Hebron General Hospital, Barcelona, Spain. mlabrador@vhebron.net
Martinez
Ma Angeles
MA
Selva-O'Callaghan
Albert
A
Delgado
Juan Francisco
JF
Martínez-Gómez
Xavier
X
Trallero-Araguás
Ernesto
E
Rodriguez-Sanchez
Jose Luis
JL
Vilardell-Tarrés
Miquel
M
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
D001323:Autoantibodies; D001685:Biological Factors; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D007633:Keratins; D012217:Rheumatoid Factor