Suppressive effects of interleukin-10 on human mononuclear phagocyte function against Candida albicans and Staphylococcus aureus

The effects of interleukin (IL)-10, a potent antiinflammatory cytokine, on human monocyte functions against two medically important pathogens, Candida albicans and Staphylococcus aureus, were studied. Incubation with 20- 100 ng/mL IL-10 for 2-3 days decreased the fungicidal activity of monocytes against serum-opsonized C. albicans blastoconidia (P ≤ .04), reduced their capacity to damage unopsonized hyphae (P ≤ .006), and suppressed superoxide anion production in response to phorbol myristate acetate (P = .019) and N- FMLP (P = .04) but not to serum-opsonized blastoconidia. Paradoxically, IL- 10 enhanced phagocytic activity of monocytes against serum-opsonized blastoconidia (P<.01). In addition, IL-10-treated monocytes demonstrated decreased bactericidal activity (P = .046) but no change in bacterial phagocytosis. These findings demonstrate an overall suppressive role of IL- 10 on human monocyte function against C. albicans and S. aureus and may have important implications in the use of this cytokine.