Inhibition of macrophage phagocytosis of Escherichia coli by mannose and mannan.

1. We investigated the possibility that Candida albicans and Escherichia coli are interiorized by thioglycollate-elicited peritoneal macrophages by interacting with the same receptor. 2. D-mannose (50 mM), a sugar recognized by mannose receptors, reduced the phagocytosis of C. albicans and E. coli to 46% and 38% of control values, respectively. The presence of 50 mM galactose or glucose did not affect the phagocytosis of either microorganism. However, mannan from Saccharomyces cerevisiae (0.5 mg/ml) inhibited phagocytosis by 70% for both microorganisms. 3. The ingestion of C. albicans and E. coli was reduced by 85% and 95%, respectively, in the presence of 10 mM EGTA. 4. These results suggest that the mannose receptor, which mediates the recognition of C. albicans by macrophages, might also mediate the phagocytosis of Escherichia coli 0111.