Method to prove investigation of particles by macrophages with light microscopy

Research on phagocytosis is often hampered by the inability to distinguish whether (opsonized) particles have been ingested by phagocytes or are only attached to the surface of these cells. Treatment of the cells after phagocytes to remove all extracellular particles makes it possible to evaluate phagocytosis with certainty by light microscopy. Opsonized erythrocytes attached to the macrophage surface are usually removed by hypotonic lysis. The present report describes the advantages of the use of lysostaphin to lyse Staphylococcus aureus and of xylene, chloroform or dioxane to dissolve polystyrene latex beads on the surface of peritoneal macrophages and embryonic fibroblasts. This procedure facilitates differentiation between professional and facultative phagocytes.