INVITRO INHIBITION OF ADHESION OF CANDIDA-ALBICANS CLINICAL ISOLATES TO HUMAN BUCCAL EPITHELIAL-CELLS BY FUC-ALPHA-1-]2GAL-BETA-BEARING COMPLEX CARBOHYDRATES

The role of cell surface glycoconjugates as possible adhesion receptors for Candida albicans yeasts on human buccal epithelial cells was investigated by using a quantitative radiometric assay involving C-14-metabolically labeled microorganisms. Various structurally defined soluble glycopeptides and oligosaccharides were tested at a low concentration (1 mg/ml) for their ability to competitively inhibit yeast adhesion to such exfoliated cells. Comparisons were also made with various molecular species previously proposed to act as adhesion molecules. A preparation of glycopeptides derived from pooled human newborn meconiums inhibited the attachment (up to 55%) of all three clinical isolates examined. The mild hydrolysis of fucosyl residues from the above mixture totally abolished its inhibitory potency. By using human milk oligosaccharide probes, the minimal structural requirement for activity was found to be the Fuc-alpha-1 --> 2Gal-beta determinant (the H sugar sequence found on all blood group substances of the ABO [H] system). By contrast, the fucosylated determinants of the Lewis blood group system were found to be totally inactive. Total adhesion inhibitions were never obtained in the present experiments, suggesting that H disaccharide-bearing cell surface glycoconjugates could act as host receptors for C. albicans on human buccal epithelial cells as part of a mechanism involving multireceptor specificities.