Evidence for lipoxin formation by bovine polymorphonuclear leukocytes via triple dioxygenation of arachidonic acid

Abstract

Incubation of bovine polymorphonuclear leukocytes (PMNs) with arachidonic acid leads to the formation of four lipoxins. The same lipoxins are also formed upon incubation of bovine PMNs with 5(S)-hydroperoxy-6-trans-8,11,14-cis-eicosatetraenoic acid, 5-hydroxy-6-trans-8,11,14-cis-eicosatetraenoic acid, 5(S)-hydroperoxy, 15(S)-hydroxy-6,13-trans-8, 11-cis-eicosatetraenoic acid or 5(S), 15(S)-dihydroxy-6,13-trans-8,11-cis-eicosatetraenoic acid. A 5,6-epoxide as intermediate in lipoxin formation in the bovine PMN is highly improbable because the 5-hydroxy compounds are as good substrates as the 5-hydroperoxy compounds. Moreover, the two main lipoxins were found to coelute with the two lipoxins produced via a triple dioxygenation of arachidonic acid by soybean lipoxygenase-1. Hence the bovine PMN is the first cell for which evidence is presented that the formation of lipoxins proceeds mainly via triple dioxygenation and not via 15-hydroxy-leukotriene A4 as is proposed for human and porcine PMNS