Immunohistochemical localization of apolipoprotein E in atherosclerotic lesions of the aorta and coronary arteries.

The distribution of apolipoprotein E (apo E) immunoreactive substances (IRS) in atherosclerotic lesions and lesion-free areas of the aorta and coronary arteries obtained from 17 autopsied cases was studied using a specific anti-apo E serum and the unlabeled peroxidase-antiperoxidase (PAP) method. In fatty streak lesions of the aorta, many cells containing apo E-IRS were found in the deeper layer of the intima and diffuse staining of apo E in the extracellular spaces was also noted. In more advanced lesions apo E-positive cells could not be found. Immunohistochemical findings of coronary arteries differed distinctly from those of the aorta in that the apo-E-positive cells were absent in the deeper layer of the intima. The endothelial cells of coronary arteries, but not those of the aorta, showed positive staining for apo E.