The expression of anti-Candida activity in the GG2EE macrophage cell line, generated by immortalization of fresh bone marrow with v-raf and v-myc oncogenes, was studied. GG2EE cells spontaneously inhibited the growth of an agerminative mutant of Candida albicans in vitro. The anti-Candida activity was maximal after 8 h of coculture and was proportional to the effector-to-target ratio. Gamma interferon (IFN-gamma), interleukin-1 (IL-1), and tumor necrosis factor (TNF) all significantly enhanced the anti-Candida activity of GG2EE cells. In contrast, IL-3, IL-4, and colony-stimulating factor 1 were ineffective. The augmentation of anti-Candida activity was not always concomitant with enhancement of phagocytosis, since IFN-gamma and colony-stimulating factor 1, but not IL-1 or TNF, augmented the phagocytic ability of GG2EE cells. Furthermore, the augmentation of anti-Candida activity in GG2EE cells did not correlate with the acquisition of antitumor activity. In fact, none of the cytokines alone were able to induce antitumor activity in GG2EE cells, which, however, could be activated to a tumoricidal stage by IFN-gamma plus heat-killed Listeria monocytogenes. These findings demonstrate that GG2EE cells exhibit spontaneous anti-Candida activity and that such activity is enhanced by TNF, IL-1, and IFN-gamma.