Cytokine levels in serum and synovial fluid of patients with juvenile rheumatoid arthritis.

OBJECTIVE

Cytokines play an important role in mediating inflammation and in regulating the immune response of many rheumatological diseases. In patients with juvenile rheumatoid arthritis (JRA), levels of 6 cytokines, interleukin 1 alpha (IL-1 alpha), IL-1 beta (IL-1 beta), IL-2, IL-2 receptor (IL-2R), IL-6, and tumor necrosis factor alpha (TNF-alpha) were measured in serum and synovial fluid (SF) in an effort to evaluate their significance.

METHODS

Serum concentrations of the 6 cytokines were measured in 62 patients with JRA including 22 pauciarticular onset, 26 polyarticular onset, and 14 systemic onset patients, and 29 disease and healthy controls using enzyme-linked immunoabsorbent assays (ELISA). Seventeen SF from patients with JRA were examined for cytokine levels.

RESULTS

Elevated serum levels of IL-2R were found in patients with systemic onset and elevated IL-2 levels in pauciarticular and polyarticular onset JRA as compared to controls. Pauciarticular and polyarticular onset patients also had elevated IL-1 alpha and IL-6 levels. There were no statistical differences found between the groups for TNF-alpha and IL-1 beta. SF revealed elevated levels of IL-1 beta, IL-2R, and IL-6; however, correlation was noted between serum and SF levels only for IL-1 alpha, not for the other cytokines. Mean serum levels of IL-2R in all onset types with active disease and IL-6 levels in active polyarticular and pauciarticular onset were elevated when compared with mean inactive levels.

CONCLUSION

Our studies indicate that (1) IL-1 alpha, IL-2, IL-2R, and IL-6 levels are increased in serum of patients with JRA with different onset types; (2) elevated levels of IL-1 beta, IL-2R, and IL-6 are found in their SF compared to serum levels; (3) a correlation exists between serum and SF levels only for IL-1 alpha; (4) mean IL-2R levels are elevated with active disease in all onset types and mean IL-6 levels with active polyarticular and pauciarticular onset disease are elevated compared to mean levels of inactive patients; and (5) cytokines may thus play a role as inflammatory mediators in JRA.