Immune functions in melanoma patients during treatment with interferon [HuIFN-alpha (Le)] alone or in combination with cimetidine.

While leukocyte interferon was found therapeutically ineffective in a series of 20 patients with metastatic malignant melanoma, subsequent combination treatment with interferon and cimetidine induced 5 complete and 1 partial tumour remissions. Prior to interferon therapy initiation, regressor patients demonstrated a significantly greater ability to mediate antibody-dependent cellular cytotoxicity than progressor patients and also tended to have higher natural killer-cell activity. These differences were more pronounced following in vitro exposure of effector cells to interferon alone or in combination with cimetidine. During therapy the differences decreased to statistically nonsignificant levels. The number of immunoglobulin producing cells and lymphocyte proliferative responses to Con A were found to increase in both patient groups after interferon therapy initiation; but this augmentation vanished gradually upon combined treatment with cimetidine. A gradual decrease of the number of T lymphocytes and granulocytes was also recorded. None of the demonstrated alterations in the activities of circulating lymphocytes appears to be a relevant correlate to the efficacy of combined therapy compared to interferon alone.