CIMETIDINE PRESERVES NONSPECIFIC IMMUNE FUNCTION AFTER COLONIC RESECTION FOR CANCER

Fifty consecutive patients undergoing resection of colorectal cancer w ere randomized to either receive cimetidine at a dose of 400 mg bd for a minimum of 5 pre-operative days, then intravenously for 2 postopera tive days, or to act as controls. Baseline immune function was determi ned in all patients by in vitro testing of lymphocyte proliferation (L P) in response to mitogen, skin testing for cell mediated immunity (CM I) and measurement of lymphocyte subsets. Immune function was retested in both groups on the second postoperative day. In control patients t he mean postoperative LP value was 41% of pre-operative levels (P < 0. 0001) and the mean CMI reduced to 29% (P < 0.0001). Patients treated w ith cimetidine had no significant fall in these parameters. Numbers of T and natural killer (NK) cells fell after surgery in both groups, an d B cell numbers were maintained in the cimetidine group. It is conclu ded that cimetidine reduces the immunosuppression that follows colonic resection.