The production of ceroid by mouse peritoneal macrophages in vitro

Murine resident peritoneal macrophages accumulated lipid droplets and subsequently insoluble, ceroid-like material when cultured in vitro in a medium containing 33% fetal calf serum. At least some of this insoluble lipid was membrane-bound and by light microscopy it often appeared as 'rings' with a hollow centre. It is suggested that the production of ceroid may be the consequence of the uptake of lipids from the extracellular medium and the activity of the macrophage's membrane-bound oxidative microbicidal mechanisms. The results indicate that macrophages are capable of rendering lipids insoluble, supporting the suggestion that this might occur in the atherosclerotic plaque.