SOLUBLE INTERLEUKIN-2 RECEPTOR IN SERA AND SYNOVIAL-FLUIDS OF RHEUMATOID PATIENTS - CORRELATIONS WITH DISEASE-ACTIVITY

The measurement of serum soluble interleukin-2 receptor (sIL-2R), a se nsitive marker of lymphocyte activation, has been proposed as an indic ator of disease activity and ''outcome'' in patients with inflammatory diseases characterized by the activation of immune cells. Serum sIL-2 R levels have been reported higher in rheumatoid patients than in cont rols. Using an enzyme-linked immunoabsorbent assay (ELISA), we evaluat ed soluble IL-2R levels in the serum of 34 patients with RA and in the synovial fluid of 25 of these patients and we compared it with levels found in the serum of 13 healthy controls. Serum sIL-2R levels were s ignificantly elevated in RA patients compared with the healthy age-mat ched control group (P<0.005). The mean level of soluble IL-2R in synov ial fluids was significantly higher than the mean sera levels in RA pa tients (P<0.0001). Moreover, we examined the correlation between serum and synovial fluid sIL-2R levels and disease activity measures. Serum sIL-2R correlated only with ESR (P<0.04). The synovial fluid sIL-2R c orrelated with ESR (P<0.02) and a visual analogue scale (VAS) pain sco re (P<0.04). Both serum and synovial fluid sIL-2R levels correlated wi th the chronic arthritis systemic index (CASI; P<0.04 and P<0.005, res pectively). Our data suggested that in RA the measurement of sIL-2R ma y certainly mirror the degree of chronic inflammation and the continuo us activation of the immune cells in the joint, although the role of t his molecule in the immune response is still unclear.