Platelet-activating factor (PAF) is a potent phospholipid mediator that was first described by its ability to cause platelet aggregation and dilation of blood vessels. Now it is also known as a potent mediator of inflammation, allergic responses, and shock. It causes a dramatic inflammation of air passage resulting in asthmalike symptoms. Production of PAF is inducable by toxins from fragments of destroyed bacteria leading to vasodilation and a drop in blood pressure resulting in reduced cardiac output and shock.
Platelets, endothelial cells, macrophages, monocytes, and neutrophils continuously produce PAF in low quantity. PAF acetylhydrolase (PAF-AH), also known as Lipoprotein-associated phospholipase A2 (Lp-PLA2), inactivates the PAF and PAF-like phospholipids, controlling their actions. Its activity increases when specific stimuli activate inflammatory cells. Lp-PLA2 is a biomarker for cardiovascular risk assessment and is associated with unstable atherosclerosis plaques. PAF also correlates with various medical conditions like asthma, stroke, myocardial infarction, certain tumors and cancers, and various other inflammatory conditions.
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