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.