[Molecular biology of adhesion molecules--structure, expression and function of ICAM-1 and ELAM-1]

Leukocytes play some important roles in pathophysiological conditions, such as inflammation, atherosclerosis, etc. It has been known that adhesion of leukocytes to vascular endothelial cells is the initial step in these conditions. Leukocytes adhere to endothelial cells utilizing adhesion molecules, such as CD11/CD18-I CAM-1, sialyl Lewis X-ELAM-1, etc. In this paper. The structure, expression and function of ICAM-1 and ELAM-1 on the endothelium is explained. ICAM-1 is a 90 kd inducible surface glycoprotein that belongs to the immunogloblinsuperfamily. Expression of ICAM-1 on the endothelium exposed to TNF, IL-1, LPS and IFN-gamma increase. This expression peaks at about 24 hours. ICAM-1 binds to CD11a/CD18 on the surface of leukocytes and takes part in the transendothelial migration. ELAM-1 is a 115 kd inducible glycoprotein, that consists of one lectin domain, one EGF-like domain and six complement regulatory like molecules. Endothelial cells will express ELAM-1 following stimulation by TNF, IL-1 and LPS. This expression peaks at 4-6 hours, declines at 24 hours. ELAM-1 binds to sialyl Lewis X on the leukocytes and participates in the rolling phenomenon, the first step of adherence to endothelium. Clarification of the mechanism of adhesion molecules expression may facilitate the treatment and prevention of vascular diseases.