MACROPHAGES INDUCE APOPTOSIS IN NORMAL-CELLS IN-VIVO

It is well established that macrophages have a function in scavenging apoptotic bodies from cells undergoing programmed cell death, Here we show that macrophages can also induce apoptosis of normal cells, Using injected toxic liposomes to eliminate macrophages in the anterior cha mber of the rat eye, we provide direct evidence that, in vivo, macroph ages induce apoptosis in normal vascular endothelial cells during prog rammed capillary regression, Macrophage elimination resulted in the su rvival of endothelial cells that normally would die and the persistenc e of functional capillaries, Furthermore, replacement of macrophages ' rescued' lack of capillary regression, Viability of the persistent tar get cells was demonstrated through their lack of apoptotic morphology, expression of intracellular esterases and synthesis of DNA, These res ults uncover a new function for macrophages in the remodeling of tissu es through the induction of programmed cell death and provide direct e vidence of a key role for macrophages in capillary regression.