Phagocytosis of apoptotic cells

Removal of apoptotic cells by phagocytes plays an important role in many biological processes, including embryological development and tissue remodelling. In addition, it has become apparent that one of the key mechanisms for the successful resolution of inflammation is the orchestrated clearance of apoptotic inflammatory cells by phagocytes (e.g., macrophages and dendritic cells) and other cells known to have phagocytic capacity (e.g., hepatocytes, endothelial cells, epithelial cells, etc.). Furthermore, phagocytosis of apoptotic cells is an active and highly regulated process that not only serves to remove potentially histotoxic cells from the inflammatory milieu, but also directs the phenotype of the phagocytic cell to be anti-inflammatory. Convincing evidence has been presented that reduced or dysregulated phagocytosis of apoptotic cells contributes to the development and propagation of inflammatory disorders. Conversely, enhanced phagocytosis of apoptotic cells may be exploited for therapeutic gain. Indeed, powerful anti-inflammatory drugs such as the glucocorticoids have been shown to augment clearance of apoptotic cells which may contribute to their therapeutic effectiveness. In this chapter, we describe methods for studying phagocytosis of apoptotic cells.