Macrophage activation: priming activity from a T-cell hybridoma is attributable to interferon-gamma.

Abstract

Antiviral and macrophage-priming activities in the supernatant medium of a subclone of a concanavalin A-stimulated mouse T-cell hybridoma were investigated. The 2 activities were associated with a MW of .apprx. 50,000 and could not be separated by various approaches. Both activities were eliminated by a highly specific neutralizing antibody against mouse interferon-.gamma., but not by antibody against interferon-.alpha. and -.beta.. The ratio of primary to antiviral activity in the hybridoma culture supernate was indistinguishable from the ratio obtained with mouse interferon-.alpha. prepared by recombinant DNA technology. The priming activity in hybridoma culture supernates was attributable to interferon-.gamma.. This mediator is one form of the lymphokine macrophage-activating factor. Interferon-.gamma. was > 800 times more efficient at priming mouse macrophages for tumor cell killing than was a mixture of interferon-.alpha. and -.beta.. Type II interferon may have greater immunoregulatory potential than type I interferons.