[Monocyte-endothelium relations]

Abstract

Monocytes and endothelial cell interactions play a key role in the development of vascular lesion, inflammation and atherosclerosis. Leukocyte adhesion is mediated through specific molecules CD11/CD18 complexes on the leukocyte side and the ELAM (Leukocyte Adhesion Molecule) ICAM (Intercellular Adhesion Molecule) on the endothelium cell surface. Several monocyte products damage endothelial cells such as free radicals, oxygen peroxides, proteases, hydrolases, lipases... Various monokines alter endothelial cell function and proliferation. Interleukin 1, gamma interferon, alpha tumor necrosis factor increase ELAM, further more they induce the synthesis of procoagulant activity by endothelial cells. Monocyte derived growth factor stimulates endothelial cells proliferation while transforming growth factors, beta (TGF beta) and TNF alpha inhibit endothelial cell growth. Lipid products of monocyte origins such as leukotrienes induce an activation of endothelial cells which results in a production of prostacyclin. Monocytes may also participate in the coagulation process by producing thromboplastin and coagulation factors and facilitating the tenase (activation of factor X) complex formation. On the other hand, monocyte also synthesize tissue plasminogen activator and inhibitor. The numerous factor produced by monocytes may affect in different ways the endothelial cell behavior.