Failure of cimetidine as an immunomodulator in cancer patients and normal subjects

Our pilot study of cimetidine as an immunomodulator in cancer patients showed no effect at clinically used doses on total blood, neutrophil, lymphocyte, or monocyte count, quantitative immunoglobulin, percentage of E-rosetting cells, phytohemagglutinin responses or delayed hypersensitivity responsiveness. We concluded that in clinically used doses, cimetidine produces no significant immunomodulation either in vivo or in vitro.