Exposure of phosphatidylserine on the surface of apoptotic lymphocytes triggers specific recognition and removal by macrophages.

摘要: During normal tissue remodeling, macrophages remove unwanted cells, including those that have undergone programmed cell death, or apoptosis. This widespread process extends to the deletion of thymocytes (negative selection), in which cells expressing inappropriate Ag receptors undergo apoptosis, and are phagocytosed by thymic macrophages. Although phagocytosis effete leukocytes has been known since time Metchnikoff, only recently it recognized apoptosis leads surface changes allow recognition removal these before they lysed. Our data suggest specifically recognize phosphatidylserine is exposed on lymphocytes during development Macrophage apoptotic was inhibited, a dose-dependent manner, liposomes containing phosphatidyl-L-serine, but not other anionic phospholipids, phosphatidyl-D-serine. Phagocytosis also inhibited L isoforms compounds structurally related phosphatidylserine, glycerophosphorylserine phosphoserine. The membranes bound increased amounts merocyanine 540 dye relative indicating their membrane lipids were more loosely packed, consistent with loss phospholipid asymmetry. Apoptotic shown express (PS) externally, because PS surfaces accessible derivatization fluorescamine, expressed procoagulant activity. These observations lose asymmetry expose outer leaflet plasma membrane. Macrophages then phagocytose after specific PS.