Anti-cyclic citrullinated peptide (anti-CCP) antibodies in children with juvenile idiopathic arthritis

OBJECTIVE: To determine if anti-cyclic citrullinated peptide antibodies (anti-CCP) can be detected in sera of patients with juvenile idiopathic arthritis (JIA) and if they can be used to identify patients with a more destructive course of disease. METHODS: One hundred serum samples of 71 patients with JIA taken at different time points in their disease course were analyzed by a commercially available anti-CCP ELISA. Followup serum samples from 28 patients were also tested. Correlations between anti-CCP and disease characteristics, medication, and radiological damage (presence of joint space narrowing and/or erosions) were also determined. RESULTS: The serum samples came from patients of all 8 different subtypes of JIA (mean age: 9.6 years, median: 10.5; disease duration mean: 39 months, median: 24) including 11 polyarticular rheumatoid factor positive (IgM-RF) patients. Anti-CCP was positive in 73% of the IgM-RF positive JIA patients and in 3% of the other JIA patients (p < 0.0001). Disease duration, medication, and anti-nuclear antibody positivity did not differ significantly between anti-CCP positive and negative patients. Testing of followup samples showed almost identical anti-CCP results. All IgM-RF positive JIA patients had radiological damage (p < 0.001). Of the anti-CCP positive patients, 80% had radiological damage resulting in a significant difference between anti-CCP positive and negative patients (p = 0.009) with an odds ratio (OR) of 12.7, but corrected for IgM-RF, the OR was no longer significant (p = 0.88). CONCLUSION: Anti-CCP antibodies can be detected in the sera of patients with JIA but almost exclusively in the subset of patients with polyarticular IgM-RF.