EXPANDED CD4(-LYMPHOCYTES FROM PATIENTS WITH CROHNS-DISEASE()CD45RO(+) PHENOTYPE AND DEFECTIVE PROLIFERATIVE RESPONSE IN T)

Background & Aims: An abnormal immune response may play a pathogenic r ole in Crohn's disease, The aim of this study was to determine the rol e of regulatory T cells in Crohn's disease. Methods: T-cell phenotype and function were studied in blood lymphocytes from patients with Croh n's disease and a control group consisting of healthy donors and patie nts with ulcerative colitis, Results: Flow cytometric studies showed a significant increase in the percentage of CD3(+)DR(+) and CD4(+)CD45R O(+) T cells in patients with Crohn's disease, T cells from patients w ith Crohn's disease and ulcerative colitis showed a defective prolifer ative response after stimulation with surface mitogenic ligands (phyto hemagglutinin and anti-CD28 or anti-CD3 antibodies), Soluble interleuk in-2 receptor alpha was augmented in the Crohn's disease and ulcerativ e colitis groups, In the Crohn's disease group, impairment of T-lympho cyte proliferation was normalized by exogenous interleukin 2, although endogenous interleukin-2 production and interleukin-2 receptor a expr ession were normal, Conclusions: An in vivo expansion of CD4(+) T lymp hocytes with memory phenotype and impaired T-cell proliferation that c an be restored by pharmacological amounts of interleukin 2 was found i n patients with Crohn's disease, There is a severe immunodisturbance i n the T-cell compartment of patients with either clinically active or inactive Crohn's disease.