Natural cell-mediated cytotoxicity against Candida albicans induced by cyclophosphamide: nature of the in vitro cytotoxic effector.

We have recently reported the in vivo modulation of resistance to experimental Candida albicans infection by cyclophosphamide (150 mg/kg intraperitoneally) in mice and have shown that increased resistance to the microbial challenge occurs 12 to 21 days after treatment with the drug (Bistoni et al., Infect. Immun. 40: 46-55, 1983). The event is accompanied by the appearance of a highly candidacidal cell population in the spleen and the activation of a subpopulation of natural cytotoxic effectors reactive in vitro against YAC-1 tumor cells. We now provide evidence that these anti-YAC-1 cytotoxic effectors are clearly distinct from the cyclophosphamide-induced candidacidal effectors, which seem to belong to a macrophage-monocyte lineage. The enhanced cytotoxic activity induced by cyclophosphamide was not restricted to C. albicans but was also exerted against a panel of Candida strains.