Functional identity between murine γ Interferon and macrophage activating factor

Abstract

We have previously suggested that two lymphokine activities–macrophage activating factor (MAF) and γ interferon (IFN-γ)–are mediated by the same molecule^1,2. Striking similarities were noted in their cellular biosynthesis, rate of inactivation with acid treatment and heating, and elution profiles on Sepha-cryl S-200. In addition, highly specific polyclonal antibodies to murine IFN-γ neutralized MAF and IFN-γ to a similar degree. However, definitive studies require a pure product and we now report that murine IFN-γ that had been cloned and expressed in a simian nonlymphoid cell line shows MAF activity. But it is not yet known whether IFN-γ is responsible for all the MAF activity in media conditioned by T cells as the possibility for MAF heterogeneity remains.