CELL COMPOSITIONS OF CORONARY AND AORTIC ATHEROSCLEROTIC LESIONS IN WHHL RABBITS DIFFER - AN IMMUNOHISTOCHEMICAL STUDY

This study investigated whether coronary atherosclerosis was different from aortic atherosclerosis in Watanabe heritable hyperlipidemic rabb its. Atherosclerotic lesions were immunohistochemically stained by usi ng a monoclonal antibody for rabbit macrophages (RAM-11) and a monoclo nal antibody for muscle actin (HHF35) and were also subjected to conve ntional staining. The areas of the major lesional components, ie, macr ophages, smooth muscle cells, collagen fibers, and extracellular lipid deposits, were measured with a color image analyzer. The percent macr ophage area in coronary lesions was significantly lower compared with aortic lesions at all stages (early fatty streak, transitional, and ad vanced), while the percent smooth muscle cell area and collagen area w ere significantly higher in early fatty streak lesions of the coronary arteries. In addition, the macrophage area/smooth muscle cell area ra tio was significantly lower in coronary lesions compared with aortic l esions at all stages. In conclusion, coronary atherosclerosis had a sm all number of macrophages and was rich in smooth muscle cells, whereas aortic atherosclerosis showed the opposite features. These results su ggested that the role of macrophages and smooth muscle cells in the in itiation and/or progression of coronary atherosclerosis differs from t he role of these cells in aortic atherosclerosis.