Direct evidence for a protein recognized by a monoclonal antibody against oxidatively modified LDL in atherosclerotic lesions from a Watanabe heritable hyperlipidemic rabbit.

Low density lipoproteins (LDL) that have been oxidatively modified have been implicated in the pathogenesis of atherosclerosis. Monoclonal antibodies were generated against oxidatively modified human low density lipoproteins (OxLDL); these antibodies reacted with OxLDL, but did not react with native LDL, either in an enzyme-linked immunosorbent assay (ELISA) or a Western blot analysis. The anti-OxLDL antibodies did react with other modified forms of LDL (eg, acetylated LDL, malondialdehyde-modified LDL, and cell-modified LDL) that were recognized by the scavenger receptor on macrophages. Single- and double-label immunofluorescence of atheromatous lesions from a Watanabe heritable hyperlipidemic (WHHL) rabbit demonstrated some colocalization of proteins detected by anti-LDL and anti-OxLDL antibodies. However, clearly there were also areas stained by the anti-OxLDL antibodies that did not stain with anti-LDL. Staining of the lesion by the anti-OxLDL antibody was abolished by adsorption of the antibody with OxLDL, but not by adsorption with LDL or bovine serum albumin. Arterial tissue from a control New Zealand White rabbit did not show staining with anti-LDL or anti-OxLDL antibodies. These observations suggest that OxLDL (or possibly other proteins recognized by the anti-OxLDL antibody) is present in atheromatous lesions of WHHL rabbits, and are consistent with oxidatively modified lipoproteins having a role in atherogenesis.