Lymphocyte transformation in the mesenteric lymph nodes of patients with Crohn's disease.

The response of lymphocytes from peripheral blood and mesenteric lymph nodes to stimulation with phytohaemagglutinin in vitro has been studied in eight patients suffering from active Crohn's disease. Patients with Crohn's disease exhibited reduced responses when compared with similar studies performed in control subjects. The impaired responses of circulating lymphocytes from these patients were marked on culture in autologous serum and were not improved by culture in homologous AB serum. Lymphocytes from lymph nodes directly draining diseased bowel exhibited lower responses than those from nodes at the root of the mesentery, which in turn were lower than those of circulating lymphocytes.