Selective acylation of lyso platelet activating factor by arachidonate in human neutrophils.
Human polymorphonuclear leukocytes (PMN) incubated with 1-O-[3H]alkyl-2-acetyl-sn-glycero-3-phosphocholine (1-[3H]alkyl-2-acetyl-GPC; platelet activating factor) inactivated the compound by removing the acetyl group and replacing it with a long chain acyl residue. The nature of the acyl group added at the 2-position of the 1-O-[3H]alkyl-2-acyl-GPC formed was examined by argentation chromatography and by reverse phase high performance liquid chromatography. A striking selectivity for arachidonate was observed in the acylation reaction. The major labeled component of the starting material was the 1-O-hexadecyl-linked species; high performance liquid chromatography analysis revealed that 75 to 80% of this component was acylated by arachidonate. Similarly, based on argentation thin layer chromatography, approximately 80% of the total starting material was acylated by tetraenoic acyl residues. The incorporation of 1-O-[3H]alkyl-2-lyso-GPC into 1-O-alkyl-2-acyl-GPC by the PMN was compared; no difference in the acylation pattern was observed with the 2-acetyl and 2-lyso precursors. Thus, activation of the PMN does not appear to be required to elicit the selectivity for arachidonate. When labeled 1-palmitoyl-2-lyso-GPC was compared in the system under the same conditions, it was also preferentially acylated by arachidonate; thus, it is not clear at this time whether or not the selectivity for arachidonate is physiologically limited to platelet activating factor. Our findings suggest a close relationship exists between the metabolism of platelet activating factor and arachidonate in human PMN.
D000215:Acylation; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D009504:Neutrophils / Q000378:metabolism*; D010972:Platelet Activating Factor / Q000031:analogs & derivatives* / Q000378:metabolism; D014316:Tritium
D001095:Arachidonic Acids; C029271:O-deacetyl platelet activating factor; D010972:Platelet Activating Factor; D014316:Tritium; D016718:Arachidonic Acid