Background Leukocyte recruitment is an early event in atherogenesis, and the leukocyte adhesion molecules E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) recently have been detected in human atherosclerosis. However, no previous study has evaluated either the distribution of these three molecules at different sites within the arterial intima or their relation to plaque leukocyte content.

Methods and Results Immunohistochemistry was performed on 99 coronary artery segments (34 controls and 65 with atherosclerotic plaque) to identify E-selectin, ICAM-1, VCAM-1, macrophages, smooth muscle cells, and T lymphocytes. For each segment, the presence or absence of adhesion molecule was determined at the arterial lumen, on intimal neovasculature, and on intimal nonendothelial cells. Each segment was scored for intimal macrophage and T-lymphocyte densities on a semiquantitative scale of 0 to 3. In atherosclerotic plaques, the prevalences of E-selectin, ICAM-1, and VCAM-1 on plaque neovasculature were twofold higher than their prevalences on arterial luminal endothelium. E-selectin was the only adhesion molecule for which expression on arterial luminal endothelial cells was more prevalent in plaques than in control segments. Increased plaque intimal macrophage density was associated with expression of VCAM-1 on neovasculature (P<.01) and on nonendothelial cells (P<.01). Increased plaque intimal T-lymphocyte density was associated with the presence of both ICAM-1 and VCAM-1 on neovasculature (both P<.01) and on nonendothelial cells (both P<.01).

Conclusions In atherosclerotic plaques, the expression of all three leukocyte adhesion molecules was more prevalent on intimal neovasculature than on arterial luminal endothelium. Further, the presence on neovasculature and nonendothelial cells of VCAM-1 and ICAM-1 was strongly associated with increased intimal leukocyte accumulation. These findings suggest that leukocyte recruitment through and/or activation of intimal neovasculature may play important roles in the pathogenesis of human atherosclerosis.