Stimulation of phagocytosis and phagosome-lysosome fusion by glycolipids from Grifola frondasa (Maitake).

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In this report, I attempted to elucidate the relationship between the structure of glycolipids from Grifola frondosa (Maitake) and the mechnism of phagocytic processes in human monocytes (MN) or polymorphonuclear leukocytes (PMN). The characteristic lipid components of Grifola frondosa (Maitake) were cardiolipin (CL), phosphatidylserine (PS) phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidic Acid (PA), phosphatidylcholine (PC), phosphatidyl-ethanolamine (PE), and three classes of glycolipids (MGL-1,2,3). The structures of glycolipids from Maitake were determined by thin layr chromatography (TLC), Infrared spectrometry, FAB mass spectrometry and NMR spectrometry. The effect of glycolipids on phagocytosis by human PMN or MN using killed Staphylococcus aureus cells coated with glycolipids (MGL-1,2,3) was examined. The rate of phagosome-lysosome fusion by PMN was determined by counting acridine orange-stained bacteria under a fluorescence microscope. Superoxide anion production was determined by the reduction of cytochrome c. Both phagocytosis and phagosome-lysosome fusion of MGL-2 was stimulated in dose-dependent manner, while MGL-1 and MGL-3 did not. Relative phagosome-lysosome fusion rate of MGL-2-coated staphylococci was six times higher than that of the noncoated control and phagocytic rate was twice, respectively. The superoxide anion release from PMN was not affected by MGL-2. I compared the effect of lipopolysaccharide (LPS) from Salmonella enteritidis with that of MGL-2 from Maitake. The glycolipid (MGL-2) reversed the inhibition of phagocytosis by LPS.