Interferon and spontaneous cytotoxicity in man. I. Enhancement of the spontaneous cytotoxicity of peripheral lymphocytes by human leukocyte interferon.

A purified preparation of human leukocyte interferon used at this hospital in the treatment of malignant diseases was tested for its ability to modify the spontaneous cytotoxicity of peripheral lymphocytes from healthy donors. The inhibitory effect of allogeneic lymphocytes on the (3H)thymidine incorporation of a lymphoblastoid cell line, Raji, was augmented by the presence of interferon or by pretreatment of the lymphocytes with interferon. This form of pretreatment also increased lymphocytes' capacity for reducing the number of surface-adherent tumor cells in a microassay. Moreover, lymphocytes treated with interferon exhibited an enhanced cytotoxic capacity for target cells on incubation with such cells labelled with 51CR.