Transcellular metabolism of arachidonic acid: increased platelet thromboxane generation in the presence of activated polymorphonuclear leukocytes.

摘要: Human polymorphonuclear leukocytes (PMN) activated by n-formyl- methionyl-leucyl-phenylalanine (fMLP), in the presence of cytochalasin B, are able to induce activation coincubated autologous platelets “via” cathepsin G released from azurophilic granules. However, thromboxane (Tx) B2 production this system cannot be completely explained G-stimulated platelet arachidonate metabolism. Indeed, amount TxB2 found supernatants platelet/PMN suspensions challenged with 1 mumol/L fMLP was twofold fourfold higher than that measured when were stimulated fMLP-activated PMN. In present report, we analyzed possibility PMN-induced is result transcellular metabolism arachidonic acid (AA) between PMN and platelets. 3H-AA-labeled used test if a transfer AA or metabolite(s) occur Our results showed that: (1) 3H-TxB2 3H-12-HHT synthesized mixed unlabeled platelets; (2) total radioactivity fMLP-stimulated increased platelets, whereas membrane content unesterified 3H-AA reduced; (3) cyclooxygenase inhibition prevents 3H- synthesis; (4) G-induced antiprotease eglin C blocks formation TxB2. These data show experimental used, use PMN-derived unmetabolized synthesize