Effect of sub-inhibitory concentrations of amphotericin B on the yeast surface and phagocytic killing activity

Amphotericin B (AmB) is the major antifungal drug used for the treatment of opportunistic fungal pathogens. In this study, we investigate another more subtle effect of this antifungal than ergosterol interaction, the effect of AmB pre-treatment of several fungi on cell surface charge. Pre-treatment of the yeasts with sub-inhibitory concentrations (SIC) of AmB also affects the phagocytic killing of yeasts. Phagocytosis of yeast takes into account the cell surface properties and was greater in yeast treated by AmB than controls. In order to explain this phenomenon, the cell wall charged components were quantified and compared to the control. Results show an increase of Glc-N in cell wall treated cells and reduction of amino acids and phosphorus. In addition, the variation of cell wall components with cell surface properties and the consequences which can be generated on the phagocytosis of the yeasts have been correlated. Results show a significant difference of the zeta-potential, which is a measure of the net distribution of electrical charges of the fungal cell surface between the treated cells and the controls. Pre-treatment of the yeast by AmB produces variations of cell wall component. These events on cell wall composition are correlated to cell surface status.