Quantifying Phagocytosis by Immunofluorescence and Microscopy.

Phagocytosis is the actin-driven internalization of solid particles, utilized by phagocytic immune cells to sequester potentially infectious microorganisms. Aided by the innate and adaptive immune system, the activation of various phagocytic receptors triggers a cascade of downstream signaling mediators that drive actin and plasma membrane remodeling. Modulation of these molecular players can lead to distinct changes in the capacity and rates of phagocytosis. Here, we present a fluorescence microscopy based technique to quantify phagocytosis using a macrophage-like cell line. We exemplify the technique through the phagocytosis of antibody-opsonized polystyrene beads. This method can be extended to other phagocytes and phagocytic particles.