Soluble interleukin-2 receptor as a marker of lymphocyte activation in childhood Crohn's disease.

Serum concentrations of the soluble form of the interleukin-2 receptor (sIL-2R) were determined by an enzyme-linked immunosorbent assay in a group of 39 pediatric and adolescent patients with Crohn's disease and in age-matched ulcerative colitis patients and controls. sIL-2R levels were found to be elevated in patients with Crohn's disease (p less than 0.001), and increased sIL-2R levels were detected in patients with clinically more severe disease. sIL-2R levels correlated more closely with other laboratory markers of disease activity than with a disease activity score. A progressive increase in sIL-2R levels was noted to correlate with endoscopic measurement of disease extent, while sIL-2R levels did not correlate with other markers of systemic lymphocyte activation, suggesting possible local mucosal production. Sequential determinations in individual patients revealed a good correlation between sIL-2R and clinical course. More important, elevated levels of sIL-2R preceded clinical relapse of asymptomatic patients. We conclude that sIL-2R measurement may be a useful adjunct to clinical assessment and routine laboratory testing in pediatric and adolescent patients with Crohn's disease and that serial levels may be predictive of clinical course and the response to therapy.