Cholesterol esterification in macrophages. Stimulation by lipoproteins containing apo B isolated from human aortas.

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Abstract
A lipoprotein fraction possessing many of the characteristics of plasma low density lipoproteins (P-LDL) was isolated from homogenates of lesioned human aortas by affinity chromatography. In contrast to P-LDL, this fraction, termed A-LP, was found to be more electronegative than P-LDL and to stimulate cholesterol esterification in mouse peritoneal macrophages (MPM). This stimulation tended toward saturation at approximately 100 micrograms/ml lipoprotein cholesterol. Cholesterol esterification was partially inhibited by fucoidin, a competitive inhibitor of the scavenger receptor on MPM. These results suggest that A-LP is recognized by a high affinity binding site on MPM. Stimulation of cholesterol esterification in MPM by A-lP was inhibited by the lysosomotropic agent, chloroquine, indicating that degradation in lysosomes was a prerequisite for cholesterol esterification. Substantial degradation of apo B within the intact A-LP was demonstrated by SDS-PAGE and immunoblotting. This degradation could be respo...