β-1,2-Linked Oligomannosides fromCandida albicansBind to a 32-Kilodalton Macrophage Membrane Protein Homologous to the Mammalian Lectin Galectin-3

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Abstract
β-1,2-linked oligomannoside residues are present, associated with mannan and a glycolipid, the phospholipomannan, at theCandida albicanscell wall surface. β-1,2-linked oligomannoside residues act as adhesins for macrophages and stimulate these cells to undergo cytokine production. To characterize the macrophage receptor involved in the recognition ofC. albicansβ-1,2-oligomannoside we used the J774 mouse cell line, which is devoid of the receptor specific for α-linked mannose residues. A series of experiments based on affinity binding on eitherC. albicansyeast cells or β-1,2-oligomannoside-conjugated bovine serum albumin (BSA) and subsequent disclosure with biotinylated conjugated BSA repeatedly led to the detection of a 32-kDa macrophage protein. An antiserum specific for this 32-kDa protein inhibitedC. albicansbinding to macrophages and was used to immunoprecipitate the molecule. Two high-pressure liquid chromatography-purified peptides from the 32-kDa tryptic digest showed complete homology to galectin-3 (previously designated Mac-2 antigen), an endogenous lectin with pleiotropic functions which is expressed in a wide variety of cell types with whichC. albicansinteracts as a saprophyte or a parasite.