Interferon and spontaneous cytotoxicity in man. II. Studies in patients receiving exogenous leukocyte interferon.

. The spontaneous cytotoxicity of peripheral lymphoid cells from five tumor patients was measured before and at various times after the first injection of human leukocyte interferon (IF). Four of the patients' lymphocytes exhibited cytotoxicity before the IF injection. After injection of IF there was an initial decrease in cytotoxicity, followed by an increase to 1.5-5 times above the preinjection level, the peak being reached at 12 hours. Thereafter the spontaneous cytotoxicity decreased but usually remained elevated for 24 hours after the injection. The lymphocytes of the fifth patient had very low spontaneous cytotoxicity before the injection of IF, and this did not markedly change afterwards. The proportion of E-rosette forming cells seemed to decrease slightly in all patients after the injection, followed by a normalization at 24–48 hours.