New insights into the mechanism for clearance of apoptotic cells

Apoptosis is a physiological mechanism for the removal of unwanted or damag ed cells. Apoptotic cells are rarely seen in living tissues, however, becau se of their rapid and efficient removal by phagocytosis. Phagocytotic cells such as macrophages or dendritic cells recognize apoptotic cells by specif ic changes of cell surface markers, which usually are not present on normal cells. One such event is the exposure of phosphatidylserine, which moves f rom the plasma membrane inner leaflet to the outer leaflet in preapoptotic cells. An unresolved problem, however, was the nature of the phosphatidylse rine receptor on the phagocytotic cells. In a recent issue of Nature, Fadok et al.((1)) have reported the cloning of a phosphatidylserine receptor usi ng an antibody raised against activated macrophages, Antibody treatment of these macrophages blocks this capacity to engulf. (C) 2000 John Wiley & Son s, Inc.