PHAGOCYTOSIS AND INTRACELLULAR KILLING OF CANDIDA-ALBICANS BY MACROPHAGES EXPOSED TO MYELOPEROXIDASE

Candida albicans is an opportunistic pathogen whose resurgence coincid es with the rising number of AIDS patients, Neutrophils are known to b e involved in the clearance of Candida infections; however, the role o f macrophages in host defenses against this organism is not well under stood. The present study was undertaken to examine an unrecognized int eraction between neutrophils and macrophages resulting in enhanced kil ling of candidae in vitro, Murine peritoneal macrophages exposed to re combinant myeloperoxidase exhibited enhancement of the respiratory bur st, increased phagocytosis, and a dose-dependent increase in intracell ular killing of Candida species. Radical scavengers reduced the killin g, indicating a role of reactive oxygen intermediates in the candidaci dal activity observed. These data suggest that at the site of infectio n, myeloperoxidase released from neutrophils activates macrophages and induces microbicidal activity.