[Platelet-modified LDL: uptake and metabolism in macrophages]

Mouse peritoneal macrophages accumulate large amounts of cholesterol ester when incubated with chemically or biologically modified lipoproteins. Incubation of LDL with platelet secretory products for 2 hours at 37 degrees C decreases its protein and cholesterol content. Subsequently this modified LDL, named PCM-LDL, enhances in-vitro platelet aggregation. When it is incubated with cultures of macrophages, cholesterol accumulates in the cells and esterification is increased. PCM-LDL is taken up by macrophages via a receptor-mediated mechanism, independent of the scavenger receptor for acetyl-LDL. Its degradation in lysosomes is required for stimulation of cholesterol ester synthesis.