Comparison between famotidine and ranitidine immunomodulatory effects in man

In the present study the effects of the histamine type 2 antagonist drugs famotidine (FMT) and ranitidine (RNT) on immune functions in human subjects were compared. Administration of FMT (40 mg orally) enhanced the lymphocyte responsiveness in the allogeneic mixed reaction (MLR), whereas it did not affect the lymphocyte responses to mitogens or in autologous mixed reactions (AMLRs). Administration of RNT (150 mg orally) enhanced the lymphocyte responsiveness to mitogens and in AMLRs without affecting that in MLR. The authors did not find any modification of either the absolute number of T and B eclls or the percentage of lymphocyte subsets in peripheral blood following administration of the two drugs. In conclusion, this study shows that: (a) FMT and RNT exert immunomodulatory effects in man; (b) each drug displays a different pattern of immunological activities; (c) the immunomodulatory effects seem to be related to the direct influence of the drugs on lymphocytes rather than to redistribution of lymphocyte subsets between lymphoid organs or to modifications in expression of membrane markers.