Reduced suppressor cell activity in intestinal lymphocytes from patients with Crohn's disease.

Suppressor cell activity in intestinal lymphocytes was investigated by a coculture assay with autologous peripheral blood lymphocytes. Greater than 45% suppression was found in 7 out of 10 patients without Crohn's disease. Reduced suppressor cell activity was found in intestinal lymphocytes isolated from 7 out of 8 patients with Crohn's disease. Intestinal lymphocytes from patients with Crohn's disease demonstrated a significantly greater response to phytohemagglutinin-P than lymphocytes isolated from non-Crohn's patients. However, this difference could not be explained by alterations in proportions of T lymphocytes as intestinal T lymphocytes from non-Crohn's disease patients (54%) were not significantly different from those found in patients with Crohn's disease (57%). Indomethacin, a prostaglandin synthetase inhibitor, decreased the proliferative response of intestinal lymphocytes to phytohemagglutinin-P whereas the response of peripheral blood lymphocytes was enhanced, thus providing further evidence that intestinal lymphocytes may represent a functionally distinct population from circulating lymphocytes. Cimetidine, a H2-receptor antagonist, had no effect on the response of intestinal lymphocytes to phytohemagglutinin-P. These results provide evidence to support the concept that disturbed immunoregulation at the mucosal level is found in Crohn's disease.