Effects of culture conditions on the in vitro infection of fibroblasts by Candida albicans
The effects of yeast culture age, carbon source, growth temperature, and germ-tube inducers on adherence to primary fibroblast cultures was studied in conjunction with the determination of adherence-mediated mammalian cell damage by measuring chromium-51 release from fibroblast monolayers. The results indicated that yeast culture age affected adherence only when the yeasts were grown at 37 °C, not after growth at 28 °C. At 37 °C, quantitatively fewer exponential-phase, glucose- or galactose-grown yeasts adhered to fibroblasts than did yeasts that were in lag or stationary phases. The reduced adherence correlated with less chromium-51 release and reduced germ-tube formation. The addition of germ-tube inducers, such as N-acetyl-D-glucosamine or serum, to exponential-phase yeasts caused an increase in germ-tube formation with a concomitant increase in yeast adherence and release of chromium-51 from the monolayers. Exponential-phase galactose-grown yeasts were more responsive to serum-induced germ-tube formation, germ-tube elongation, and fibroblast adherence than were exponential-phase glucose-grown yeasts. In addition, exponential-phase galactose-grown yeasts caused more chromium-51 release from monolayers in the presence of serum than did glucose-grown yeasts. Overall, conditions that enhanced germ-tube formation and elongation resulted in greatest adherence-mediated damage to the monolayers. Key words: Candida albicans, fibroblasts, morphogenesis.