Cell Meter™ Fluorimetric Phagocytosis Assay Kit *Red Fluorescence*

Phagocytosis is defined as the cellular uptake of particles within a plasma-membrane envelope by a cell. The process of phagocytosis is critical in the innate immune response by engulfment and destruction of invading microorganisms. Phagocytosis is also required in maintaining tissue homeostasis and remodeling by the clearance of apoptotic bodies. The uptake mechanism of phagocytosis depends on the size of the particles, receptor-ligand interactions, and involvement of the cytoskeleton. Once internalized, the phagosome fuses with lysosomes to form secondary phagolysosome for digestion, resulting in progressive decrease of pH. Our Cell Meter™ Fluorimetric Phagocytosis Assay Kit utilizes a unique pH dependent Protonex™ 600 Red-latex bead conjugates. The beads are in ready to use suspension. Unlike most of the existing fluorescent dyes, the Protonex™ 600 Red-latex bead conjugate is non-fluorescent outside of the cells. However, its fluorescence dramatically increases as they are inside the acidic phagosomes/phagolysosomes. This characteristic makes it easy to use without trypan blue quenching step and a robust tool to study phagocytosis and its regulations. Cell Meter™ Fluorimetric Phagocytosis Assay Kit also includes a green fluorescent cell viability dye, which allowing the simultaneous detection of both live cells and the process of phagocytosis by fluorescent microscopy. This assay can also be adapted for fluorescence micro-plate reader and flow cytometry detections.