Soluble interleukin-2 receptor and disease activity in Crohn's disease.

An ELISA was used to measure concentrations of soluble interleukin-2 receptor (sIL-2R) alpha chain in the sera of patients with Crohn's disease. In a group of 56 patients, serum concentrations of sIL-2R were significantly raised in patients with active disease compared with patients with inactive disease and age-matched control populations. There was a significant correlation between serum sIL-2R concentration and disease activity as assessed by the Harvey-Bradshaw index (r = +0.60; P less than 0.001) and laboratory measurements of disease activity including C-reactive protein (r = +0.79; P less than 0.001), ESR (r = +0.64; P less than 0.001) and platelet count (r = +0.533; P less than 0.001). We also found a negative correlation between sIL-2R levels and serum albumin (r = -0.66; P less than 0.001). In longitudinal studies, changes in the concentration of serum sIL-2R reflected the changes in disease activity. Soluble IL-2R, therefore, offers a new measure of disease activity in Crohn's disease with a potential advantage over other laboratory parameters currently available in that it may reflect more accurately the underlying immunopathogenic process.