Influence of endogenous pro-inflammatory cytokines on neutrophil-mediated damage of Candida albicans pseudohyphae, quantified in a modified tetrazolium dye assay.

For quantitative assessment of polymorphonuclear granulocyte (PMN)-mediated pseudohyphal damage, an improved tetrazolium (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide; XTT) dye assay was developed. The modified assay proved to be a reliable indicator of viable pseudohyphal inoculum sizes. In addition, the influence of various endogenous pro-inflammatory cytokines on the capacity of PMN to damage Candida albicans pseudohyphae was investigated. PMN obtained from mice in which the genes encoding for tumor necrosis factor-α /lymphotoxin-α (TNF/LT), interferon-γ (IFNγ), interleukin (IL)-1α, or IL-1β were disrupted, showed a significantly reduced pseudohyphal damage capacity in comparison with control PMN. The reduction amounted 25% for TNF -/ - LT -/ - , 11% for IFNγ -/ - , 21% for IL-1α -/ - , and 34% for IL-1α -/ - β -/ - PMN. In contrast, deficiency of IL-12 or IL-18 did not result in a diminished capacity to damage pseudohyphae and the capacity of PMN to damage Candida pseudohyphae was even slightly increased by 10% in IL-18 -/ - mice. These data suggest that endogenous pro-inflammatory cytokines are able to modulate antihyphal activity of PMN, the main effector cells against disseminated candidiasis by virtue of their capacity to kill both Candida blastoconidia and pseudohyphae. [ABSTRACT FROM AUTHOR]