sIL-2R levels in rheumatoid arthritis: poor correlation with clinical activity is due in part to disease duration.

The serum levels of soluble interleukin-2 receptors (sIL-2R) were measured in an attempt to determine whether they correlated with 'disease activity' in 59 patients suffering from rheumatoid arthritis. Our results indicate that serum levels of sIL-2R do not permit patients to be classified as having active or inactive disease according to standard clinical indices. A correlation between sIL-2R and disease duration could offer one explanation for the current discrepancies found in the literature.