Studies on the subpopulation and function of peripheral lymphocytes, and lymphocyte reactivity to colonic mucosal antigen and bacterial antigen in patients with ulcerative colitis and Crohn's disease.

Immunological studies were carried out in fifteen cases of ulcerative colitis, three cases of tuberculous colitis, four cases of Crohn's disease and one case of Behcet's disease diagnosed by X-ray, endoscopy or biopsy mainly from the standpoint of cellular immunity. In patients with ulcerative colitis the T-cell population and PHA responsiveness of peripheral lymphocytes were both depressed more than in the control group. At different stages of the disease, the deviation of the values of PHA responsiveness of lymphocytes showed a rather wide range in the active stage and there was also immunological instability. However, when the disease entered remission, the immunological conditions settled down and the pathological condition appeared stable. In contrast to the nonspecific immunological conditions mentioned above, characteristically, there were many examples of a positive lymphocyte response to colonic mucosal and bacterial antigens. In all cases of Crohn's disease the lesions are in the small intestine and there was a reduced response to PHA lymphocytic stimulation which was more pronounced than that in patients with ulcerative colitis. PHA response was also high in tuberculous colitis cases.