Immunohistochemical Detection of 13(R)-hydroxyoctadecadienoic Acid in Atherosclerotic Plaques of Human Carotid Arteries Using a Novel Specific Antibody

13-Hydroxyoctadecadienoic acid (13-HODE) is a major component of oxidized low density lipoprotein (OxLDL), which has been shown to have a crucial role in atherogenesis. Of the 13-HODE stereoisomers, 13(S)-HODE and 13(R)-HODE, little is known about the latter in contrast to the former. To detect 13(R)-HODE in atherosclerotic lesions, we prepared a mouse monoclonal antibody against 13(R)-HODE. Competitive enzyme-linked immunosorbent assay clarified the selective reaction of a clone mAb 13H1 with both free and bovine serum albumin-conjugated forms of 13(R)-HODE but not other oxidized lipids including 13(S)-HODE. Immunohistochemical analysis revealed the colocalization of 13(R)-HODE immunoreactivity with the OxLDL marker oxidized phophatidylcholine immunoreactivity in vascular endothelial cells, macrophages and migrating vascular smooth muscle cells in atherosclerotic plaques of human carotid arteries. The present results provide in vivo evidence for the formation of 13(R)-HODE in atherosclerotic lesions of carotid arteries.