PEROXIDATION OF HUMAN BLOOD LIPOPROTEINS INDUCED BY EXOGENOUS HYPOCHLORITE OR HYPOCHLORITE GENERATED IN THE SYSTEM OF MYELOPEROXIDASE PLUS H2O2 PLUS CL-

Oxidation of human plasma lipoprotein (LP) was studied in the presence of exogenous hypochlorite anion (OCl-) or OCl- generated in the ''mye loperoxidase + H2O2 + Cl-'' system. OCl- effectively initiates peroxid ation of lipids extracted from LP and those within LP particles, as ca n be judged from accumulation of secondary (thiobarbituric acid [TBA] reactive) and final (Schiff bases) products of lipid peroxidation (LPO ) in LP after incubation with myeloperoxidase or exogenous OCl-. Very low density and low density lipoproteins classified as atherogenic LP are more sensitive to OCl--induced LPO than high density lipoproteins. These data allow us to propose that OCl- secreted by activated neutro phils and monocyte-macrophages can produce oxidative modification of L P in vivo. The latter is known as a risk factor in the development of atherosclerosis.