Phagocytosis Triggers Macrophage Release of Fas Ligand and Induces Apoptosis of Bystander Leukocytes

摘要: Human monocyte/macrophages (Mφ) exposed to nonparticulate stimuli can express cell surface Fas ligand (FasL) and release active soluble FasL (sFasL). We now report that monocyte/Mφ-ingesting opsonized zymosan released sFasL conditioned supernatants so these triggered Fas-mediated apoptosis of “bystander” monocytes FasL-negative neutrophils. Furthermore, identical results were seen with Mφ taking up apoptotic neutrophils, whereas medium by phagocytizing latex beads had no proapoptotic effects upon neutrophils despite the presence sFasL. These data suggest hitherto unrecognized existence a feedback loop requiring factors in addition may promote resolution inflammation-phagocytic clearance cells leading killing bystander leukocytes macrophages.