Macrophage colony-stimulating factor induction of enhanced macrophage anticryptococcal activity: synergy with fluconazole for killing.

Enhancement of anticryptococcal activity in macrophages by macrophage colony-stimulating factor (M-CSF) and possible synergy between macrophages and fluconazole for killing of Cryptococcus neoformans were tested. M-CSF (48 h)-treated macrophages underwent dramatic morphologic changes and inhibited cryptococcal multiplication by 96% +/- 4%, which was greater (P < .001) than that of macrophages cultured in medium alone. M-CSF (5000 units/mL) induced optimal anticryptococcal activity but did not increase percentage of phagocytosis. NG-mono-methyl-L-arginine did not affect enhanced fungistatic activity. For a very fluconazole-sensitive isolate, fungistatic macrophages synergized with fungistatic doses of fluconazole for killing; for a less sensitive isolate, synergy was significant only when macrophages were activated with M-CSF or interferon-gamma plus lipopolysaccharide; for a fluconazole-resistant isolate, macrophages collaborated with fluconazole for additive fungistasis but not killing, and M-CSF-treated macrophages were significantly more fungistatic with fluconazole than were nonactivated macrophages.