Simultaneous evaluation of membrane bound and soluble interleukin 2 receptor expression in the blood and synovial fluid of patients with rheumatoid arthritis.

We studied the levels of membrane-bound and soluble-form interleukin 2 (IL-2) receptors in forty patients with rheumatoid arthritis. Levels of IL-2 receptors in the sera and synovial fluid of patients with rheumatoid arthritis were elevated when compared to values observed in normal sera and synovial fluid derived from the osteoarthritic joint. Simultaneous elevation of IL-2 receptor expression in blood and synovial fluid lymphoid cells was also detected, but no correlation was found between the two parameters nor between serum IL-2 receptor levels and the hemosedimentation rate. We conclude that measurement of serum concentrations of soluble IL-2 receptors should be used with caution as an index of disease activity, but may be useful when used in conjunction with other parameters in the management of patients with rheumatoid arthritis.