Immunohistochemical localization of apoprotein B in aortas from hyperlipemic swine. Preferential accumulation in lesion-prone areas.

In hyperlipemic swine, areas of the aortic arch that accumulate intravenously injected Evans blue dye (blue areas) appear to be more susceptible to early atherogenesis than adjacent areas that are devoid of dye uptake (white areas). We used immunofluorescence microscopy to determine the localization of apoprotein-B (apoB) in these blue and white areas, and in intimal cell masses (ICMs) of the abdominal aortas obtained from hyperlipemic and normolipemic swine. The results showed that before aortic lesions were visible grossly or microscopically, extracellular accumulations of apoB occurred preferentially in the thickened intima of blue areas and in ICMs of the abdominal aorta. Normal white areas in the aortic arch and abdominal aortas, and in the aortas obtained from control swine showed negligible immunoreactivity. Thus, the accumulation of apoB at anatomic sites predilected to early atherogenesis lends further evidence linking these lipoproteins with atherogenesis.