INTERLEUKIN-2 RECEPTOR LEVELS IN SERA OF PATIENTS WITH RHEUMATOID-ARTHRITIS TREATED WITH SULFASALAZINE, PARENTERAL GOLD, OR PLACEBO

Objective. To evaluate the associations of soluble serum interleukin-2 receptor (sIL-2R) levels in patients with rheumatoid arthritis (RA) w ith clinical and laboratory measures of disease activity and the predi cted response to therapy. Methods. sIL-2R levels were determined by EL ISA in 137 patients with RA, not previously treated with 2nd line ther apy. Patients were enrolled in a prospective, randomized, placebo cont rolled trial of sulfasalazine (SSZ) versus gold sodium thiomalate (GST M), sponsored by the Cooperative Systematic Studies of Rheumatic Disea ses. Using correlation analysis and regression modeling, the clinical utility of sIL-2R as a measure of disease activity and predictor of ou tcome was assessed. Results. 91 women and 46 men with a mean age of 51 +/- 13 years and mean duration of disease of 64 +/- 78 months partici pated in this study, The mean sIL-2R level in all patients with RA was markedly elevated (980 +/- 589 U/ml) compared with that in healthy co ntrol subjects (446 +/- 196 U/ml; p = < 0.0001). There was no correlat ion between the sIL-2R levels and the joint pain/tenderness count, eit her at study entry or completion. There were significant positive corr elations between the baseline sIL-2R and baseline erythrocyte sediment ation rate (ESR) and between the change in sIL-2R and the change in ES R. Both a multiple linear regression model and a multiple logistic reg ression model showed that baseline sIL-2R levels were not predictive o f clinical outcome, Conclusion, sIL-2R levels are significantly elevat ed in patients with active RA and correlate positively with ESR. Howev er, these results indicate that in patients with early RA, sIL-2R leve ls are neither associated with standard disease activity criteria nor predictive of the response to therapy with SSZ or GSTM, even after con trolling for the simultaneous effects of other important clinical vari ables.