The effect of cimetidine on immunological parameters in Crohn's disease: a double blind trial.

Thirty-six patients with Crohn's disease were entered into a double-blind trial to assess any beneficial effect that cimetidine might have on immunological and clinical status. Eighteen patients were randomized to receive cimetidine, 1 g orally for 28 days, and the other 18 patients to receive a placebo. There was no alteration in clinical status in the cimetidine-treated group. Although 64% of the patients were anergic, augmentation of skin tests to candida, mumps, tuberculin, streptokinase/streptodornase and trichophyton antigens, was not observed in the cimetidine-treated patients. The patients with Crohn's disease, as a whole had higher absolute numbers of suppressor T-lymphocytes, 0.70 X 10(9)/litre (0.21-2.36, n = 35) compared to control values, 0.5 X 10(9)/litre (0.16-1.55, n = 25) (P less than 0.05). However, there was no significant difference in proportions of suppressor and helper T-lymphocytes, lymphocyte activation and humoral immunity after cimetidine treatment. The lack of any clear modulation of immunity by cimetidine, would be against trying H2 antagonists in a long term clinical trial.