Interleukin-6 and soluble interleukin-2 receptor in juvenile chronic arthritis: Correlations with clinical and laboratory parameters

We sought to determine whether levels of interleukin-6 and soluble interleukin-2 receptor were correlated with clinical parameters including functional capacity indices such as Steinbrocker's class and the Juvenile Arthritis Functional Assessment Report (JAFAR) score, with tests for inflammation, and/or with immunological parameters in 24 patients with active polyarticular or pauciarticular juvenile chronic arthritis. Levels of interleukin-6 and soluble interleukin-2 receptor were significantly higher in juvenile chronic arthritis patients than in healthy controls (p<0.005 and p<0.00005, respectively). Interleukin-6 levels were correlated with the following parameters: number of painful joints (p<0.025); Ritchie's index (p<0.025); visual analog scale pain score (p<0.025); Steinbrocker's class (p<0.025); JAFAR score determined by patients (p<0.05); JAFAR score determined by parents (p<0.05); erythrocyte sedimentation rate (p<0.0002); and serum levels of C-reactive protein (p<0.0003), hemoglobin (p<0.05), albumin (p<0.025), and alpha2-globulins (p<0.025). Levels of soluble interleukin-2 receptor did not correlate with any of the parameters studied. Levels of interleukin-6 and soluble interleukin-2 receptor were not correlated with each other. Abnormal levels of interleukin-6 or soluble interleukin-2 receptor were not significantly associated with the presence of antinuclear antibodies, IgM-rheumatoid factor, IgA rheumatoid factor or anticardiolipin antibodies. Our findings suggest that interleukin-6 is a useful parameter for assessing juvenile chronic arthritis and that the potential clinical value of elevated levels of soluble interleukin-2 receptor in this disease needs to be further evaluated in longitudinal studies.