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A platelet-activating factor, also known as a PAF or paf-acether is a potent phospholipid activator and mediator of many leucocyte functions, including platelet aggregation, inflammation, and anaphylaxis.
It is produced in response to specific stimuli by a variety of cell types, including neutrophils, basophils, platelets, and endothelial cells. Several molecular species of platelet-activating factor have been identified which vary in the length of the O-alkyl side chain. It is an important mediator of bronchoconstriction.
Its alkyl group is connected by an ether linkage at the C1 carbon to a sixteen carbon chain. The acyl group at the C2 carbon is an acetate unit whose short length increases the solubility of PAF, allowing it to function as a soluble signal messenger.
It causes platelets to aggregate and blood vesicles to dilate. At a concentration of 10^-12 M, PAF causes life threatening inflammation of the airways to induce asthma like symptoms. Toxins such as fragments of destroyed bacteria induce the synthesis of PAF which causes a drop in blood pressure and reduced volume of blood pumped by the heard which leads to shock and maybe death.
It was discovered by French immunologist Jacques Benveniste in 1970.
See also
External links
"Platelet-activating factor"