To determine the prevalence of anti-chromatin antibodies (Abs) in juvenile rheumatoid arthritis (JRA) and to assess any association between the presence of anti-chromatin Abs and clinical subsets of the disease.
IgG anti-chromatin Abs and anti-extractable nuclear antigens (ENA) Abs were detected by an enzyme-linked immunosorbent assay (ELISA), and antinuclear Abs (ANA) by indirect immunofluorescence in sera of 89 children with JRA. Ten children with systemic, 32 with polyarticular and 47 with pauciarticular disease onset (uveitis occurred in 17/47 children) were studied. As a control group, 12 sera of patients suffering from idiopathic uveitis and 31 age- and-sex-matched healthy children (HC) were examined.
Abs to chromatin were detected in 14/47 (29.8%) of children suffering from pauciarticular onset JRA and in this group the higher prevalence of anti-chromatin Abs has been found in children with chronic uveitis (p = 0.002). Anti-chromatin positivity was observed in 2/10 (20%) of systemic and in 3/32 (9.3%) of polyarticular onset JRA. Furthermore, none of the patients with idiopathic uveitis and HC had Abs to chromatin. anti-chromatin Abs titers remained relatively stable over a 6-month control period.
Our results confirm previous data about the presence of circulating anti-chromatin Abs in juvenile arthritis. Interestingly, anti-chromatin Abs were significantly higher in the group of patients with pauciarticular onset with past or present history of uveitis, than in patients without ocular involvement. A long-term follow-up study could be useful to demonstrate the potential utility of these autoantibodies in diagnosing, classifying and treating children affected.