Structure elucidation of platelet activating factor derived from human neutrophils.

Platelet activating factor (PAF) synthesized by human neutrophils challenged by opsonized zymosan or calcium ionophore was isolated from cells and buffer using Bligh and Dyer extraction following the addition of tracer amounts of tritiated-PAF. The extract was subjected to TLC separation of phospholipid classes, followed by reverse phase HPLC for molecular species separation. All fractions were measured for radioactivity, biological activity and fast atom bombardment mass spectrometry. While the radioactive tracer PAF could be separated into three molecular species, PAF biological activity eluted as a single component which was characterized as 1-O-hexadecyl-2-acetyl-glycero-3-phosphocholine. The lack of molecular species heterogeneity of PAF produced in response to stimuli implies a higher degree of control of biosynthesis than previously suspected.