Modulation of PAF production by incorporation of arachidonic acid and eicosapentaenoic acid in phospholipids of human leukemic monocyte-like cells THP-1 Corinne A.E. Martin–Chouly, Ve ´ronique Menier, Aziz Hichami, Hind Youmine, Franc ¸oise Noel, Fre ´de ´rique Pedrono, Alain B. Legrand Laboratoire de Pharmacologie Mole ´culaire, Faculte ´ de Pharmacie, Universite ´ de Rennes I, 2 Avenue du Pr Leon Bernard, 35043 Rennes, France Received 5 December 1998; received in revised form 5 February 1999; accepted 9 November 1999 Abstract Stimulated leukocytes generate platelet-activating factor (PAF) from membrane 1-O-alkyl-2-acyl-sn-glycerophosphocholine through hydrolysis of fatty acid and subsequent acetylation at the sn2 position of glycerol. Since the enzymes involved in the hydrolysis step of PAF biosynthesis have relative selectivity for arachidonic acid (AA), the fatty acid composition of PAF precursors might modulate PAF production. We studied the effect of AA and eicosapentaenoic acid (EPA) incorporation on PAF biosynthesis, by measuring the incorporation of [ 3 H]acetate, in Ca 2+ ionophore (A23187)-stimulated human leukemic monocyte-like cells, THP-1. Supplementation of THP-1 with AA (25 M, 1 week) or EPA (25 M, 1 week) led to their efficient incorporation, in comparable quantities and with similar distributions, into phosphatidylcholine and phosphatidylethanolamine, and to a lesser extent into phosphatidylinositol. THP-1 cells supplemented with AA or with EPA synthetized similar amounts of PAF and of acyl analog of PAF under resting condition. However, AA-supplemented cells responded to A23187 stimulation by important raises of PAF (+125.71%) and of acyl analog of PAF (+381.75%) productions, whereas the same stimulation had little effect or no effect at all in cells supplemented with EPA. These results show that both EPA and AA may influence PAF production through their incorporation into PAF precursors, indicating that PAF production might be modulated by the fatty acid composition of its precursors. © 2000 Elsevier Science Inc. All rights reserved. * Corresponding author. Tel.: +33-2-99-33-69-43; fax: +33-2-99-33-68-88. E-mail address: corinne.chouly@univ-rennes1.fr (C.A.E. Martin–Chouly) Prostaglandins & other Lipid Mediators 60 (2000) 127–135 0090-6980/00/$ – see front matter © 2000 Elsevier Science Inc. All rights reserved. PII: S0090-6980(00)00058-1