TUMOR-NECROSIS-FACTOR ENHANCES LOW-DENSITY-LIPOPROTEIN OXIDATIVE MODIFICATION BY MONOCYTES AND ENDOTHELIAL-CELLS

The effect of tumor necrosis factor on the oxidative modification of L DL by U937 human monocytes or murine endothelial cells was studied by determination of the lipid peroxidation product content and the electr ophoretic mobility of the particle. In the range of concentrations fro m 2.5 to 10 ng/ml, the cytokine induced a dose-dependent increase in c ellular-induced oxidation of LDL. This effect was accompanied by a sti mulation of LDL degradation by J774 macrophage-like cells. Concurrentl y the TNF-treated cells secreted superoxide anion with a higher rate. Since LDL oxidation is believed to be an important feature in the form ation of the atherosclerotic plaque, the described effects of TNF migh t be of importance in long-term exposure to this cytokine during infla mmation.