CIRCULATING LEVELS OF INTERLEUKIN-1-BETA AND OF INTERLEUKIN-1 RECEPTOR ANTAGONIST IN SYSTEMIC JUVENILE CHRONIC ARTHRITIS

Objective. To measure circulating interleukin 1 beta (IL-1 beta) and I L-1 receptor antagonist (IL-1Ra) levels in patients with systemic juve nile chronic arthritis (JCA) and to evaluate their correlation with di sease activity. Methods. IL-1 beta and IL-1Ra levels were measured by ELISA in 45 patients with JCA (20 systemic, 10 polyarticular and 15 pa uciarticular) and in 15 healthy controls. Results. Plasma IL-1 beta le vels were undetectable in the majority of patients with systemic JCA, and detectable levels were not associated with different treatments or with parameters of disease severity. Serum IL-1Ra levels were markedl y increased in patients with systemic JCA and significantly correlated with the persistence of systemic features, the extent and severity of joint involvement, and with C-reactive protein concentrations. Serum IL-1Ra levels were also significantly correlated with IL-6 levels. Con clusion. These results argue against a relevant role of IL-1 in system ic JCA. The increase in IL-1Ra levels does not appear to reflect an in crease in IL-1 production, but may rather be induced by, IL-6.