Ceroid accumulation by murine peritoneal macrophages exposed to artificial lipoproteins: ultrastructural observations

Murine resident peritoneal macrophages were maintained in cell culture in a medium containing 10% lipoprotein-deficient fetal calf serum to which various artificial lipoprotein particles (coacervates of lipid and bovine serum albumin) had been added. The uptake and intracellular fate of these particles was studied by electron microscopy. The appearance of material accumulating within the cells varied according to the nature of the lipid component of the ingested particles. Lipids which are readily oxidised (cholesteryl linoleate, cholesteryl arachidonate, trilinolein) were associated with the formation of ceroid within membrane-bound structures. Less readily oxidized lipids (cholesteryl oleate, triolein) were not associated with ceroid accumulation but instead the cells contained numerous nonmembrane-bound lipid inclusions. The appearances of the ceroid within the murine peritoneal macrophages are similar to those of ceroid in macrophages in human atherosclerotic lesions.