Platelet activating factor is:

a. Generated by the action of phospholipase A2 on membrane phospholipids 

c. Synthesized by endothelial and other cells

d. Exerts a variety of biologic effects which are platelet-independent

Like the eicosanoids, platelet-activating factor (PAF) is not stored in cells but is rapidly produced during inflammation. PAF exerts a variety of biologic effects that are platelet-independent. The synthesis of PAF is initiated by the activation of phospholipase A2. Activation of phospholipase A2 releases arachidonic acid in addition to lyso-PAF. Hence, PAF synthesis and eicosanoid production are coordinately regulated. PAF is synthesized on activation of a variety of inflammatory cells including platelets, neutrophils, basophils, mast cells, mononuclear phagocytes, eosinophils and vascular endothelium. PAF is a stimulatory agonist for many inflammatory cells, as well as for smooth muscle cells, vascular endothelium and others. PAF enhances the ability of neutrophils to respond to challenge with N-formylpeptides and LTB4. There is considerable overlap and redundancy in the effects produced by PAF and eicosanoids.