Activities of enzymes that metabolize platelet-activating factor (1-Alkyl-2-acetyl-sn-glycero-3-phosphocholine) in neutrophils and eosinophils from humans and the effect of a calcium ionophore
Lee, T.C.; Malone, B.; Wasserman, S.I.; Fitzgerald, V.; Snyder, F.
Biochemical and Biophysical Research Communications 105(4): 1303-1308
1982
ISSN/ISBN: 0006-291X PMID: 6808993 Document Number: 192486
Enzymatic systems in human blood cells are described with regard to the activation and inactivation of a biologically active phospholipid (1-alkyl-2-acetyl-sn-glycero-3-phosphocholine) with hypotensive, platelet-aggregating and inflammatory properties. The results document the presence of alkyldihydroxyacetone-phosphate synthase (forms the O-alkyl linkage in lipids), 1-alkyl-2-lyso-sn-glycero-3-phosphocholine:acetyl-CoA acetyltransferase (produces the biologically active molecule), and 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine:acetylhydrolase (destroys the biological activity) in human neutrophils and eosinophils. Both the acetyltransferase and acetylhydrolase activities are increased severalfold after treatment of normal neutrophils with ionophore A23187; alkyldihydroxyacetone-phosphate synthase activity is not influenced by the ionophore. Eosinophils isolated from patients with eosinophilia have significantly greater activities of all the enzymes studied than eosinophils isolated from normal individuals. The acetyltransferase responsible for 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine synthesis may serve an important role in human blood cells that release this biologically active phospholipid. The acetyltransferase activity was dramatically influenced by Ca flux.