Induction of macrophage growth by negatively charged phospholipids

The effects on macrophage growth of seven phospholipids that are normally present in cell membranes were examined. Phosphatidylcholine and sphingomyelin which are the main phospholipid constituents of mammalian cell membranes, had no effect on growth of macrophages. Phosphatidylinositol also had little effect. On the other hand, the relatively minor components phosphatidylserine, phosphatidylglycerol, cardiolipin, and phosphatidic acid, which are negatively charged phospholipids, significantly enhanced macrophage growth. These findings suggest that some acidic phospholipids may increase survival or growth of tissue macrophages when they are ingested by the cells in materials containing phospholipids, such as effete autologous cells or bacteria.