Interleukin-6, soluble interleukin-2-receptor and soluble interleukin-6-receptor in sera of patients with rheumatoid arthritis: influences of disease activity and drug therapy.

Cytokines and their receptors play a fundamental role in the development and maintenance of the inflammatory process in rheumatoid arthritis (RA). The purpose of this study was to evaluate sIL-2R, sIL-6R and IL-6 levels in the sera of 48 RA patients and to correlate them with disease activity, indicators of inflammatory process as ESR and CRP, and drug treatment modalities. IL-6 and sIL-2R levels were positively correlated with disease activity, ESR and CRP. No correlation between sIL-6R levels and these markers were observed. Our results suggest that different drug therapies have a decisive influence on the levels of selected cytokines. All investigated disease-modifying antirheumatic drugs (DMARDs) were able to reduce the IL-6 level significantly. Non-immunosuppressive DMARDs decreased the amount of circulating sIL-2R more than immunosuppressive drugs. Treatment with methotrexate resulted in a significant reduction of circulating levels of sIL-6R compared to azathioprine therapy. Under low dose glucocorticoid therapy, significantly lower levels of sIL-6R were found than in patients without glucocorticoids. In conclusion, the results provide some arguments in favour of combined drug therapies, which might possibly enhance the effectiveness of RA therapy.