Abstract
Vascular endothelial cells (ECs) form a one cell layer on the luminal surface of all blood and lymphatic vessels, the endocardium, blood-brain barrier, and renal glomerulus. EC function and phenotype can vary depending upon the tissue, vascular region, or given microenvironment. These versatile cells form the vanguard at the dynamic interface between the blood and tissue space, play central roles in the maintenance and regulation of vascular system homeostasis, the integration of immune cell signaling and trafficking, and diverse pathological processes including inflammation, tumor metastasis, and diabetes. ECs express class I and class II MHC molecules, interact with, and modulate, immune cell function by induced expression of adhesion molecules and cytokines, and recruit T cells into inflammatory sites by functioning as antigen presentation cells (APCs).