Factors influencing the interaction of Candida albicans with fibroblast cell cultures

The interaction of Candida albicans clinical isolates with primary and established fibroblast cultures was studied. The intent was to determine whether yeast adherence and invasion of nonendothelial cell monolayer cultures could be quantitated reproducibly and whether this system could be used for future studies on yeast pathogenesis. Our results demonstrated that specific interactions between the yeast cells and fibroblasts only occurred at 37 degrees C and correlated with the germination process. Fluorescent-antibody staining indicated that invasion or tight associations between the germinating yeast cells and mammalian cells occurred after less than 3 h of incubation. Yeast adherence was estimated radiometrically and trypsin-resistant interaction with individual mammalian cells (infection) was measured microscopically after inoculated monolayer cells were detached with trypsin. We demonstrated that both types of association were time dependent at 37 degrees C; neither was affected by the concentration of glucose used to grow the yeast cells. Primary and established fibroblast cell lines were equally susceptible to infection, but primary cells appeared to have more yeast-binding sites. Fibroblasts maintained in confluent culture for an extended period of time also appeared to have more binding sites, and while not quantitatively more susceptible to infection, the older cells were more susceptible to infection-related cell death. An established kidney epithelial cell line (MDCK) was not susceptible to either type of yeast interaction, indicating that the yeast-fibroblast associations were specific.