Suppressive Role of Sialylated N-glycans in Fc Receptor-mediated Phagocytosis by Macrophages

By culturing with tunicamycin A1, an inhibitor of N-glycosylation, or by sialidase digestion, mouse monocytic cells P388D1 were induced to carry out Fc receptor-mediated phagocytosis of IgG-coated sheep red blood cells. There was no significant difference in the numbers of IgG-coated sheep blood cells bound to the cells at 4 degrees C before and after exposure to tunicamycin or sialidase. These results suggest that sialylated N-glycans expressed on the cell surface have a suppressive role in the induction of phagocytosis, and their decreased expression or reduced sialylation results in acquisition of the phagocytic ability of the cells by affecting some processes involved in the ingestion of the particles bound to Fc receptors.