The PAF receptor binds platelet-activating factor (PAF) and is thought to mediate its action via a G protein that activates a phosphatidylinositol-calcium second messenger system. PAF is a chemotactic phospholipid mediator that possesses potent inflammatory, smooth-muscle contractile and hypotensive activity. It has been implicated as a mediator in diverse pathologic processes, such as allergy, asthma, septic shock, arterial thrombosis, and inflammatory processes. 
 
The PAF receptor is induced by granulocyte macrophage colony-stimulating factor (GM-CSF), interleukin-5 and n-butyrate. A diverse range of compounds act as PAF receptor antagonists; these may be useful pharmacologically.