OXIDIZED LOW-DENSITY-LIPOPROTEIN IS CYTOTOXIC TO HUMAN MONOCYTE-MACROPHAGES - PROTECTION WITH LIPOPHILIC ANTIOXIDANTS

Human monocyte-macrophages were incubated for 24 h with low-density li poprotein (LDL) which had been previously oxidized for varying periods up to 24 h with copper ions, in the presence or absence of DL-alpha-t ocopherol or probucol. The release of radioactivity from cells preload ed with tritiated adenine was used as an assay of toxicity. Toxicity o f oxidized LDL increased with duration of copper oxidation and with in creasing evidence of lipid oxidation, measured by assay of thiobarbitu ric acid-reactive substances and by gas chromatography. Oxidation and toxicity were inhibited by DL-alpha-tocopherol (200 mu M) and probucol (50 mu M).