Antibodies against cyclic citrullinated peptide are associated with HLA-DR4 in simplex and multiplex polyarticular-onset juvenile rheumatoid arthritis.

Objective Anti–cyclic citrullinated peptide (anti-CCP) antibodies have been detected in patients with juvenile rheumatoid arthritis (JRA), particularly in those with polyarticular, rheumatoid factor (RF)-positive JRA. Our objectives were to determine whether anti-CCP antibodies are associated with HLA–DR4 in children with polyarticular JRA, whether anti-CCP antibodies are associated with clinical features of disease, and whether affected sibling pairs (ASPs) with JRA are concordant for this antibody. Methods Stored serum samples obtained from 230 HLA-typed patients with JRA (77 with polyarticular-onset disease and 153 with pauciarticular- or systemic-onset disease), 100 JRA ASPs, and 688 healthy children were tested for anti-CCP antibodies and RF. Results Thirteen percent of the patients with polyarticular-onset JRA and 2% of the other JRA patients exhibited anti-CCP antibodies, compared with only 0.6% of the controls. Fifty-seven percent of RF-positive patients with polyarticular-onset JRA had anti-CCP antibodies. HLA–DR4–positive patients with polyarticular-onset JRA were more likely to have anti-CCP antibodies than were those without HLA–DR4 alleles (odds ratio [OR] 5.20, 95% confidence interval [95% CI] 1.30–20.9). Anti-CCP antibodies were associated with polyarticular onset (OR 7.46, 95% CI 1.99–28.0), a polyarticular disease course (OR 9.78, 95% CI 1.25–76.7), and erosive disease (OR 14.3, 95% CI 3.01–67.9). Concordance rates for anti-CCP antibodies among ASPs were statistically significant. Conclusion These data demonstrate increased anti-CCP antibody formation in HLA–DR4–positive patients with polyarticular-onset JRA. The overall prevalence of anti-CCP antibodies in JRA is low, but a substantial proportion of RF-positive patients with polyarticular-onset JRA have these antibodies. Anti-CCP antibodies in JRA are associated with polyarticular onset, a polyarticular course, and erosive disease.