title: Decreased arachidonic acid metabolism in human platelets by autologous neutrophils: possible role of cell adhesion.
abstract: The amount of the 12-lipoxygenase and cyclo-oxygenase products, 12(S)-hydroxy-(Z,Z,E,Z)-5,8,10,14-eicosatetraenoic acid (12-HETE) and 12(S)-hydroxy-(E,E,Z)-5,8,10-heptadecatrienoic acid (HHT), in human platelets stimulated by thrombin (0.1 and 2.5 units/ml), was studied in the presence of autologous neutrophils. A decreased formation of both products was induced by unstimulated neutrophils or neutrophils challenged with N-formylmethionyl- leucyl-phenylalanine (0.1 microM) or Ca2+ ionophore A23187 (0.15 microM). The effect of neutrophils was observed only in the presence of Ca2+. 12-HETE and HHT were also produced in platelets stimulated with thrombin in the absence of Ca2+ and/or Mg2+, but their level was not altered by neutrophils. 12(S),20-Dihydroxy-(Z,Z,E,Z)-5,8,10,14-eicosatetraenoic acid (12,20-DHETE), the cytochrome P-450 product from 12-HETE in neutrophils, was hardly detected, and its level did not compensate for the decrease in 12-HETE observed after platelet and neutrophil co-incubation. 5(S),12(S)-Dihydroxy-(E,Z,E,Z)- 6,8,10,14-eicosatetraenoic acid (5(S),12(S)-DHETE), the 5-lipoxygenase product of 12-HETE in neutrophils, was never detectable. In addition, the inhibition of 12-HETE and HHT formations appeared not to be due to degradation or thrombin uptake by neutrophils, nor was the decrease observed when the two cell populations were physically separated. A monoclonal antibody against the human platelet glycoprotein GMP140 (CD62), mediating Ca(2+)-dependent platelet-neutrophil adhesion, mimicked the inhibitory effect of neutrophils in a dose-dependent fashion. Furthermore, the 12-HETE and HHT productions were not affected when platelets were stimulated in the presence of neutrophils previously incubated with sialidase, which removes the sialic acid from a sialyl Lewis(x) structure assumed to be the neutrophil receptor for platelet GMP140. We conclude that the decrease in thrombin-stimulated 12-HETE and HHT formation observed when platelets were co-incubated with autologous neutrophils might be the consequence of platelet-neutrophil adherence, presumably through platelet GMP140.
authors.affiliation: INSERM U 352, Chimie Biologique INSA-Lyon, Villeurbanne, France.
authors.forename: B
authors.initials: B
authors.lastname: Chabannes
authors.forename: P
authors.initials: P
authors.lastname: Molière
authors.forename: Y
authors.initials: Y
authors.lastname: Pacheco
authors.forename: M
authors.initials: M
authors.lastname: Lagarde
mesh_terms: D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D000595:Amino Acid Sequence; D016718:Arachidonic Acid / Q000378:metabolism*; D001792:Blood Platelets / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002448:Cell Adhesion; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D008969:Molecular Sequence Data; D009439:Neuraminidase / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism*; D009842:Oligopeptides; D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins / Q000502:physiology; D013917:Thrombin / Q000494:pharmacology
chemical_list: D005231:Fatty Acids, Unsaturated; D006893:Hydroxyeicosatetraenoic Acids; D009842:Oligopeptides; D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins; D016718:Arachidonic Acid; C008033:12-hydroxy-5,8,10-heptadecatrienoic acid; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; C047981:arginyl-glycyl-aspartic acid; D009439:Neuraminidase; D013917:Thrombin; D008274:Magnesium; D002118:Calcium