Elevated serum levels of soluble interleukin-2 receptor in patients with Wegener's granulomatosis. Association with disease activity.

OBJECTIVE. To investigate whether soluble interleukin-2 receptor (sIL-2R), a marker of T cell activation, could be a useful marker of disease activity in Wegener's granulomatosis (WG). METHODS. Soluble IL-2R levels were determined by enzyme-linked immunosorbent assay. WG disease activity in 102 patients was assessed according to clinical features and levels of classic antineutrophil cytoplasmic antibody (c-ANCA) and C-reactive protein (CRP). RESULTS. Soluble IL-2R levels were higher in patients with generalized and active disease than in those with limited and inactive disease. In 25 patients with complete clinical remission, sIL-2R levels were significantly elevated, although levels of CRP and c-ANCA were normal. Eight of these 25 patients had disease relapses within 6 months. Levels of sIL-2R were significantly higher in patients who had relapses than in those who did not. Patients with clinically active WG but low c-ANCA or CRP levels had elevated levels of sIL-2R. CONCLUSION. Levels of sIL-2R correlate with disease activity in patients with WG, and may indicate imminent relapse.