Production of gamma interferon by human T and null cells and its regulation by macrophages

Human mononuclear subpopulations were tested for the capacity to produce interferon after mitogenic stimulation with protein A from Staphylococcus aureus. Mononuclear cells were separated into highly enriched macrophage, T-, B-, and null-cell subpopulations by Sephadex G-10 adherence, anti-human IgG F(ab′) two-column chromatography, and rosetting with sheep erythrocytes. Interferon (IFN) production was observed in both T- and null-cell preparations, but not in macrophage or B-cell preparations. Physicochemical and antigenic characterization of IFN from T- and null-cell preparations showed that both mononuclear subpopulations produced gamma IFN (IFNγ). Regulatory studies showed that IFNγ production was differentially regulated by macrophages. Macrophage addition to T lymphocytes augmented both cellular proliferation and IFNγ production, whereas macrophage addition to null cells suppressed IFNγ production and had no effect on the minimal proliferative response observed for these cells.