Infect Immun. 2008 Nov 3. [Epub ahead of print]


Live Candida albicans suppresses production of reactive oxygen species in phagocytes.


Wellington M, Dolan K, Krysan DJ. Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, NY, 14642.



Production of reactive oxygen species (ROS) is an important aspect of phagocyte-mediated host responses. Since phagocytes play a crucial role in the host response to Candida albicans, we examined the ability of Candida to modulate phagocyte ROS production. ROS production was measured in the murine macrophage cell line, J774, and in primary phagocytes using luminol-enhanced chemiluminescence. J774 cells, murine PMN, human monocytes, and human PMN treated with live C. albicans produced significantly less ROS than phagocytes treated with heat killed C. albicans. Live C. albicans also suppressed ROS production in murine bone marrow-derived macrophages from C57BL/6 mice, but not from BALB/c mice. Live C. albicans also suppressed ROS in response to external stimuli. C. albicans and C. glabrata suppressed ROS production by phagocytes, whereas Saccharomyces cerevisiae stimulated ROS production. The cell wall is the initial point of contact between Candida and phagocytes, but isolated cell walls from both heat killed and live C. albicans stimulated ROS production. Heat killed C. albicans have increased surface exposure of 1,3-beta-glucan, a cell wall component that can stimulate phagocytes. To determine whether surface 1,3-beta-glucan exposure accounted for the difference in ROS production, live C. albicans were treated with a sub-lethal dose of caspofungin to increase surface 1,3-beta-glucan exposure. Caspofungin-treated C. albicans were fully able to suppress ROS production, indicating that suppression of ROS overrides stimulatory signals from 1,3-beta-glucan. These studies indicate that live C. albicans actively suppresses ROS production in phagocytes in vitro, which may represent an important immune evasion mechanism.


PMID: 18981256 [PubMed - as supplied by publisher]




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