Direct modulation of human neutrophil behaviour by Candida albicans

We examined the direct effect of unopsonized yeast particles of Candida albicans on two aspects of neutrophil behaviour, namely adherence and 3H-deoxyglucose uptake. The data show that brief exposure of C. albicans to human neutrophils resulted in decreased ability of the neutrophils to adhere to Dacron fibre and take up deoxyglucose. This inhibitory effect was further shown to be dependent on yeast concentration and on the integrity of the yeast cell wall. Additional experiments indicate that this effect was direct rather than indirect through soluble mediators in the supernatant. Interference experiments with glucan and mannan, the two major polysaccharide components of the yeast cell wall, suggest that the ligand in direct interaction between C. albicans and neutrophil contains glucan. Finally, it was shown that nonpathogenic species of Candida such as C. krusei, C. parapsilosis and C. guilliermondii did not display neutrophil-modulatory properties while the occasionally pathogenic C. tropicalis did. These results indicate that C. albicans has the ability to circumvent neutrophil defence mechanisms, and may in part explain the propensity of this fungus to cause infection.