Characterization of the epitopes specific for the monoclonal antibody 9F5-3a and quantification of oxidized HDL in human plasma

Background We previously isolated a monoclonal antibody, 9F5-3a, that is specific for HDL oxidized by CuSO 4 . Methods We examined the characteristics of the 9F5-3a epitope by Western blot and measured the concentration ofoxidized HDL in human plasma by enzyme-linked immunosorbent assay using this antibody. Results The monoclonal antibody specifically reacted with oxidized HDL in a mixture of HDL, LDL and modified lipoproteins. Oxidation of the HDL particles accelerated cross-linkage of apolipoproteins caused by lipid peroxidation, and the cross-linked apolipoprotein Al selectively reacted with the 9F5-3a antibody. Mean (standard deviation) plasma concentrations of oxidized HDL were 127 (50) μg/L in 23 healthy controls, 191 (65) μg/L in 30 patients with non-insulin-dependent diabetes mellitus (P<0.01 versus healthy controls) and 200 (87) μg/L in 25 patients with coronary artery disease (P<0.01 versus healthy controls). The concentrations of oxidized HDL did not correlate with the concentrations of thiobarbituric acid-reactive substances. Conclusions The results indicate that determination of oxidized HDL concentration may be useful for identifying patients with atherosclerotic disease.