CHOLESTEROL EFFLUX TO APOA-I, HDL2, AND SERUM FROM MACROPHAGES ISOLATED FROM LOW AND HIGH HDL SUBJECTS

Oxidized LDL (Ox-LDL) was shown to be taken up by macrophages via several receptors including the acetyl-LDL(Ac-LDL), the LDL, and the Ox-LDL receptors. Cellular uptake and degradation of Ox-LDL could be dissociated from that of LDL and Ac-LDL as demonstrated by using macrophages that lack the LDL or the Ac-LDL receptors. In J-774 A.1 macrophage-like cell line unlabeled Ox-LDL reduced the 125I-Ox-LDL by up to degradation of 91% whereas unlabeled Ac-LDL and native LDL reduced 125I-Ox-LDL degradation by only 51% and 23%, respectively. Analysis of macrophage degradation of 125I-Ox-LDL in the presence of 30-fold excess concentration of LDL + Ac-LDL (to block uptake of 125I-Ox-LDL via the LDL and the Ac-LDL receptors) revealed that cellular degradation via the Ox-LDL receptor could account for 45% of the macrophage uptake of Ox-LDL.