Augmentation of natural killer cytotoxicity by alpha or gamma natural and recombinant interferons and interferon inducers. Effect of monocytes

We investigated the effect of human peripheral blood monocytes on the augmentation of natural killer cytotoxicity by α or γ natural and recombinant interferons (IFN) and certain interferon inducers. We observed that: (1) in the majority of the donors examined (75%) human peripheral blood monocytes do not affect natural killer cytotoxicity, determined by a 4-hour chromium-51 release assay, against target cells from hemopoietic human tumor cell lines. (2) Monocytes are not required and do not affect the augmentation of natural killer cytotoxicity by Escherichia coli-derived IFN-γ, natural human IFN-γ, E. coli-derived IFN-α₂ or natural human IFN-α. E. coli-derived IFN-γ and natural human IFN-γ have been reported to activate monocyte cytotoxicity determined in 72-hour assay. (3) Monocytes are not required for the augmentation of natural killer cytotoxicity against target cells from hemopoietic tumor cell lines by polyinosinic acid-polycytidylic acid or staphylococcal enterotoxin A.