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

Abstract

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. 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. 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 alpha expression were normal. 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.