BOTH MANNOSE AND BETA-GLUCAN RECEPTORS ARE INVOLVED IN PHAGOCYTOSIS OF UNOPSONIZED, HEAT-KILLED SACCHAROMYCES-CEREVISIAE BY MURINE MACROPHAGES

We studied the involvement of lectin-like receptors in phagocytosis of unopsonized heat-killed yeast (Saccharomyces cerevisiae) by murine ma crophage-like cell lines and murine peritoneal resident macrophages. F or this purpose we used a technique that allowed us to discriminate in gested and adsorbed heat-killed yeast. The internalization can be part ly inhibited by soluble polyosides such as laminarin (beta-glucan) or alpha-mannan. However, when they were used together (0.4 mg/ml alpha-m annan and 0.4 mg/ml laminarin), almost complete inhibition of phagocyt osis was obtained. These observations suggest that phagocytosis of uno psonized heat-killed yeast by murine macrophage-like cell lines as wel l as murine peritoneal resident macrophages is mediated by both mannos e and beta-glucan receptors. The respective activity of these two type s of receptors is a function of in vitro cell differentiation. To achi eve maximal phagocytosis of unopsonized heat-killed yeast, coexpressio n of both mannose and beta-glucan receptors is required.