Release of 1-O-alkylglyceryl 3-phosphorylcholine, O-deacetyl platelet-activating factor, from leukocytes: chemical ionization mass spectrometry of phospholipids.

Abstract

Evidence is presented for the simultaneous release of platelet-activating factor (PAF-acether; an anaphylaxis mediator an a platelet-aggregating factor) and of its deacetylated derivative (lyso-PAF-acether) from hog leukocytes. Spectroscopy and chemical reactions showed that the structure of O-deacetyl-PAF is 1-O-alkylglyceryl 3-phosphorylcholine, an alkyl ether analog of lyso-phosphatidylcholine. Acetylation of lyso-PAF yields a compound with biological activity and chromatographical behavior indistinguishable from those of native PAF. Lyso-PAF may be considered to be either the precursor or the enzymatic degradation product of PAF. The usefulness of chemical ionization mass spectrometry for structural determination of phospholipids is also demonstrated.