Impaired mitogenic response of peripheral blood T cells in ulcerative colitis is not due to apoptosis

An abnormal immune response may play a pathogenic role in ulcerative coliti s (UC). Animal models suggest that T-cell regulation may be of central impo rtance in the inflammatory process, Our aims were the characterization of t he phenotype and functional status of circulating T-cells in ulcerative col itis patients and to determine if activation-induced cell death in CD4(+) a nd CD8(+) lymphocytes in patients differs from healthy controls. Forty-eigh t patients (24 women and 24 men) fulfilling the histopathological, clinical , and immunological criteria for UC were studied. T-cell phenotype and func tion were studied in blood lymphocytes from patients with ulcerative coliti s and healthy donors by flow cytometric analysis, as well as [H-3]thymidine incorporation, There were no significant differences in the percentage of T-cell subpopulations (CD3, CD4, CD8) and NK cells in the different groups. The percentage of cells in growth phase S+G(2)M at two and three days of p hytohemagglutinin (PHA) stimulation was significantly decreased in UC patie nts, but the percentage of CD4(+) and CD8(+) cells in UC patients that show ed apoptosis was not significantly different than that in the control group . Proliferative responses to IL-4 also suggested that a reduced responsiven ess to this cytokine may be involved in UC, III conclusion, the impaired pr oliferative response to PHA of T lymphocytes from UC patients is not associ ated with an in vitro increase in the apoptotic response in CD4(+) or CD8() cells. A reduced IL-4 response may be involved in this peculiar mitogenic response These changes may be pathogenic or a favorable adaptive mechanism .