Attempts to characterize the T-cell population and lymphokine involved in the activation of macrophage oxygen metabolism in murine listeriosis.

Cultures of T cells from Listeria monocytogenes-immune mice, macrophages, and heat-killed Listeria organisms produced a factor(s) capable of activating macrophage oxygen metabolism. The activity depended on the presence of Lyt 1+2,3- T cells in the primary culture. Macrophage oxygen metabolism could also be induced by a L. monocytogenes-specific T-cell clone which was recently shown to mediate anti-listerial protection in vivo and to secrete interferon-gamma (IFN-gamma) in vitro. Furthermore, macrophage activation was achieved by recombinant IFN-gamma. It is concluded that acquired resistance to facultative intracellular pathogens--at least in part--depends on the activation of macrophage oxygen metabolism by IFN-gamma derived from specific Lyt 1+2,3- T cells.