IMMUNOLOGICAL EFFECTS OF LEVAMISOLE IN MICE AND HUMANS - EVIDENCE FORAUGMENTED ANTIBODY-RESPONSE WITHOUT MODULATION OF CELLULAR CYTOTOXICITY

Selected immunomodulatory effects of levamisole were studied in patien ts with asymptomatic metastatic colon cancer and in a preclinical mode l (CF1 female mice treated with methyl-azoxymethanol acetate) for colo n tumors. In the patient population studied, there was no augmentation of cellular cytotoxicity or alteration in lymphocyte subpopulations t hat participate in these functions. An increase in Fc receptor binding on circulating monocytes was apparent at the 4-week timepoint; howeve r, a corresponding increase in antibody-dependent cellular cytotoxicit y was observed in only one of the six patients studied. In most patien ts, cellular cytotoxicity diminished with time. No significant effects on cellular immunity or carcinogenesis were observed in our murine st udies. However, treatment with levamisole did increase circulating imm unoglobulin levels and IgM response in mice immunized with the T-depen dent antigen keyhole limpet hemocyanin. This parameter was not tested in the human trial. Failure to demonstrate antitumor effects on cellul ar immunity by levamisole in both human and murine studies suggests th at these effects, if they do exist, may involve immunological paramete rs that were not tested using our methods or that may not be apparent in patients with more advanced malignancy.