Immunohistochemical detection of apolipoprotein A-I and B-100 in canine atherosclerotic lesions.

We attempt to determine and compare the localization of apolipoproteins (apo) apoA-I and B-100 in atherosclerotic lesions of canine aortas, coronary arteries, and the peripheral arteries, using immunohistochemical techniques. Histopathologically, atherosclerotic lesions were characterized by deposition of lipids and infiltration of lipid-laden foamy cells in the tunica intima and tunica media, sometimes forming fibrofatty plaques containing abundant sudanophilic and mineralized material. Canine apoA (CapoA)-I and canine apoB (CapoB)-100 immunopositive signals were simultaneously observed in mild and severe atherosclerotic lesions of the aorta, coronary arteries, splenic arteries, and renal arteries in the double-immunolabeled sections. Both CapoA-I and CapoB-100 positive signals were seen in the cytoplasm of endothelial cells, smooth muscle cells, and macrophages. The subendothelial space and extracellular matrix in the tunica intima and media were also positive. Neither CapoA-I nor CapoB-100 positive signals were seen in normal arteries. These findings closely resemble those of the localization of apoA-I and apoB-100 in human atherosclerotic lesions.