Expanded CD4(+)CD45RO(+) phenotype and defective proliferative response in T lymphocytes from patients with Crohn's disease

Background & Aims: An abnormal immune response may play a pathogenic role in Crohn's disease, The aim of this study was to determine the role of regulatory T cells in Crohn's disease. Methods: T-cell phenotype and function were studied in blood lymphocytes from patients with Crohn's disease and a control group consisting of healthy donors and patients with ulcerative colitis, Results: Flow cytometric studies showed a significant increase in the percentage of CD3(+)DR(+) and CD4(+)CD45RO(+) T cells in patients with Crohn's disease, T cells from patients with Crohn's disease and ulcerative colitis showed a defective proliferative response after stimulation with surface mitogenic ligands (phytohemagglutinin and anti-CD28 or anti-CD3 antibodies), Soluble interleukin-2 receptor alpha was augmented in the Crohn's disease and ulcerative colitis groups, In the Crohn's disease group, impairment of T-lymphocyte proliferation was normalized by exogenous interleukin 2, although endogenous interleukin-2 production and interleukin-2 receptor a expression were normal, Conclusions: An in vivo expansion of CD4(+) T lymphocytes with memory phenotype and impaired T-cell proliferation that can be restored by pharmacological amounts of interleukin 2 was found in patients with Crohn's disease, There is a severe immunodisturbance in the T-cell compartment of patients with either clinically active or inactive Crohn's disease.