Activation of natural cytotoxicity of human peripheral blood mononuclear cells by interferon: a kinetic study and comparison of different interferon types.

Overnight incubation of human peripheral blood mononuclear (PBMN) cells with leucocyte interferon (leucocyte IFN) resulted in a 2-5-fold increase in natural cytotoxicity (NC) against the erythroleukaemic cell line K562. Fibroblast IFN, purified to homogeneity by zinc-chelate chromatography, stimulated NC to the same extent, while partially purified immune IFN was about twice as active. Upon gel filtration of immune IFN, NC stimulating and antiviral activity co-eluted. Treatment of PBMN cells with ammonium chloride buffer (AmCl) abrogated NC nearly completely. Incubation of AmCl-treated cells with leucocyte IFN resulted in a partial regeneration of NC. Kinetic studies revealed that this regeneration required only short exposure to IFN followed by a longer incubation period. The data are interpreted as indicating that in the process of NC activation IFN mainly acts as a trigger for precursor cells to mature into cells with NC.