INTERLEUKIN-1 RECEPTOR ANTAGONIST IN DIFFERENTIAL-DIAGNOSIS OF INFLAMMATORY BOWEL DISEASES

Background: Immunoregulatory properties of cytokines may mediate disor dered inflammatory events in inflammatory bowel diseases (IBDs). On th e basis of data obtained in experimental colitis, the hypothesis has b een advanced that in IBD the balance between interleukin-l (IL-l) and the naturally occurring IL-1 receptor antagonist (IL-1ra) might influe nce disease expression. Objective: We studied the profiles of IL-1ra a nd acute phase proteins produced by activated macrophages to determine whether the level of IL-1ra in peripheral blood is a marker of diseas e activity in IBD and a possible differential diagnostic marker. Patie nts and methods: Levels of IL-1ra, serum neopterin, urinary neopterin, cll-glycoprotein and C-reactive protein (CRP) were measured in 80 pat ients with ulcerative colitis, Crohn's disease or infectious colitis. Results: Levels of IL-1ra were markedly increased in patients with act ive ulcerative colitis or active Crohn's disease compared with those i n patients with infectious colitis. Patients with active Crohn's disea se had significantly higher serum IL-1ra levels than patients with act ive ulcerative colitis. Moreover, a positive correlation was found bet ween levels of C-reactive protein, alpha(1)-glycoprotein, and serum ne opterin and the level of IL-1ra in active Crohn's disease but not in a ctive ulcerative colitis, strongly suggesting that the pathogenesis of the two conditions differs. Conclusion: Levels of IL-l ra in the peri pheral blood of patients with IBD are of clinical relevance, represent ing a potent marker of disease activity and a possible differential di agnostic marker.