A study of the immunological effects of cimetidine in patients with lepromatous leprosy.

To test the capacity of cimetidine to enhance cellular immunity in patients with lepromatous leprosy (LL), cimetidine was given for one month to 29 inactive LL patients and 3 active LL patients. Immune function was monitored with skin tests (lepromin, PPD, candida, and trichopytin), lymphocyte transformation tests (phytohemagglutinin, BCG, and Dharmendra lepromin), and quantitation of peripheral blood lymphocyte subpopulations. A small but significant "booster" response to PPD was the only change observed in the study of patients with inactive disease, and leprosy-related reactions did not occur. In the few active LL patients studied, neither immune enhancement nor leprosy-related reactions were observed. The results of this investigation suggest that cimetidine can be used safely in patients with inactive lepromatous leprosy.