Localization of CD36 and scavenger receptor class A in human coronary arteries - a possible difference in the contribution of both receptors to plaque formation

CD36 and scavenger receptor class A types I and II (SR-AI/II) are major rec eptors for oxidized low density lipoproteins (OxLDL) expressed on macrophag es. To elucidate the role of these two macrophage scavenger receptors in th e development of coronary atherosclerosis, we examined the localization of CD36 and SR-AI/II in human coronary atherosclerotic lesions. Serial cryosta t sections of 49 coronary arteries obtained from 43 autopsied cases were ex amined immunohistochemically. Regarding the relationship between the severi ty of atherosclerosis and immunoreactivities to CD36, there was almost no i mmunoreactivity to CD36 in regions with diffuse intimal thickening, while t he expression of CD36 was accelerated in parallel with the progression of a therosclerosis. In contrast, SR-AI/II was expressed persistently from regio ns with diffuse intimal thickening to atherosclerotic plaques. We also clar ified the differential distribution of CD36 and SR-AI/II in atheromatous pl aques. Close to the luminal surface of the intima, macrophages were relativ ely small in size, contained lesser lipids, and expressed SR-AI/II more abu ndantly than CD36. In contrast, macrophages in the core region were larger in size, contained more lipids, were strongly positive for CD36 and showed a weaker immunoreactivity to SR-AI/II than those in the luminal surface of the intima. In conclusion, the expression of CD36 and SR-AI/II on macrophag es may be regulated differently in the process of coronary atherogenesis. ( C) 2001 Elsevier Science Ireland Ltd. All rights reserved.