Role of actin polymerization in monocyte phagocytosis of yeast cells effect of cytochalasin B.

The role of the cortical actomyosin-like contractile system in monocyte phagocytosis was studied by means of inhibition with cytochalasin B. Monocyte phagocytosis of yeast cells was assayed with a fluorescence extinction technique of surface-located phagocytosis which distinguishes between adherence and ingestion phases of total phagocytosis. Cytochalasin B, 10 micrograms/ml, inhibited monocyte phagocytosis by 20-30%. The cytochalasin inhibition was significant and restricted to the ingestion phase. The finding supported the hypothesis that the contractile structures of the cell have a contributory role in IgG-mediated monocyte phagocytosis on a surface. It is suggested that the cytochalasin effect reflected the role of chemotaxis in monocyte phagocytosis assayed by the present technique.