PAF is a potent pro inflammatory mediator that is formed from a membrane phospholipid in a variety of cells including, platlets, endothelial cells and leucocytes. There are three mechanisms by which PAF augments inflammation.
Firstly, there is a receptor on the surface of leucocytes for PAF. Binding of PAF results in increased expression of CD11/CD18 on the surface of the leucocyte thereby augmenting adhesion and transmigration of leucocytes. Transmigration also increases microvascular permeability.
Secondly, PAF stimulates the formation of oxygen free radicals and the release of myeloperoxidase and lactoferrin.
And finally, hypoxia stimulates endothelial cells to release PAF with further leucocyte adhesion and ICAM-1 expression.