The role of platelet-activating factor in endothelial cells.

Endothelial cells activated by receptor-mediated agonists, particularly those involved in inflammation and thrombosis, synthesize platelet-activating factor and express it on their surfaces. This PAF serves as a signal for neutrophils, and perhaps other blood cells, to bind to the endothelium. In some cases, the PAF produced by endothelial cells appears to be a sufficient stimulus for this binding, but in other circumstances it appears to act in concert with a glycoprotein, GMP-140. The synthesis and expression of PAF are tightly regulated under normal conditions, but can be induced by bacterial toxins and oxidants, which in vivo might result in vascular damage and thrombosis.