Mannose receptor contribution to Candida albicans phagocytosis by murine E-clone J774 macrophages

Mannoproteins, as the main constituents of the outer layer of yeast cell walls, are able to interact with phagocytic cells in an opsonin‐independent manner through the mannose receptor (MR) and to induce yeast ingestion by the professional phagocytes. Moreover, the MR also mediates endocytosis of soluble ligands through clathrin‐coated pits. Here, we studied some aspects of the interaction between the MR and Candida albicans using murine E‐clone macrophages and the consequences on MR trafficking. Using a pull‐down assay involving mixture E‐clone macrophage detergent lysate with mannosylated Sepharose beads and glutaraldehyde‐fixed, heat‐killed (HK) C. albicans, we found that binding of solubilized MR to mannosylated particles occurred with characteristics similar to the receptor’s cell‐surface mannose‐binding activity. We then demonstrated that MR expressed on E‐clone macrophages contributed to phagocytosis of unopsonized, HK C. albicans and that yeast phagocytosis induced a decrease in MR endocytic activity without concomitant degradation of the receptor in the time lapse studied.