Candida albicans adherence to a human oesophageal cell line

The oesophageal epithelium appears to be one of the primary cell targets of Candida albicans in AIDS patients. To study this interaction, we have established an in vitro adherence assay using a human epithelial oesophageal cell line (HET1-A). When yeast cells were grown in 500 mM D-galactose, adherence increased significantly over cultures prepared in 500 mM D-glucose. In addition to HET1-A cells, adherence of the organism grown in D-galactose to human buccal epithelial cells and a murine alveolar macrophage cell line was also higher. Adherence of yeast cells to HET1-A cells was partially inhibited in the presence of D-glucosamine or N-acetyl-D-glucosamine, but not with D-mannose, D-glucose, L-fucose or D-galactose. Attachment to HET1-A cells was studied using scanning and transmission electron microscopy. Partial phagocytosis of adhering yeast cells was observed occasionally within the first 90 min following infection, as evidenced by the formation of HET1-A pseudopodia in instances of close contact with yeast cells. The influence of D-galactose on cell surface proteins was studied by analysing beta-mercaptoethanol-extracted proteins from yeast cells grown in either 500 mM D-galactose or D-glucose. From D-galactose-grown cells only, a glycoprotein of approximately 190 kDa was observed in Aurodye-stained SDS-PAGE gels and in Western blots using an immunoglobulin fraction (IgG) prepared from sera of rabbits infected with the organism. These studies demonstrate that C. albicans adheres to human oesophageal cells and may utilize cell surface proteins whose synthesis is nutritionally regulated.