MONOCLONAL ANTIBODY-BASED IMMUNOASSAY FOR EVALUATION OF LIPOPROTEIN OXIDATION

Numerous reports indicate that the oxidation of low-density lipoprotei n (LDL) can significantly change its metabolic and physiological prope rties. Most methods for evaluation of LDL oxidation require isolation of lipoprotein, making the procedure laborious and increasing the prob ability of artifactual modification of LDL. In this paper we describe an immunochemical approach which can be used to measure the oxidation of isolated LDL and apoprotein B in unfractionated serum and to evalua te the effects of antioxidants on these processes. The procedure is ba sed on differential recognition by monoclonal antibodies of native and oxidized lipoproteins. The results obtained with our assay indicate a strong correlation between the changes of apo B epitope expression du ring oxidation and the formation of conjugated dienes, changes in lipo protein electrophoretic mobility, and interaction with fibroblast and macrophage receptors. The sensitivity of apo B to oxidation varies gre atly among serum samples obtained from individual donors. These differ ences do not correlate with the differences in sensitivity to oxidatio n of LDL isolated from the blood samples of the same donors. It is als o shown that apo B oxidation in serum can be progressively inhibited i n the presence of increasing amounts of various antioxidants. (C) 1995 Academic Press, Inc.