Xenon modulates neutrophil adhesion molecule expression in vitro

BACKGROUND AND OBJECTIVE: Xenon reduces the infarct size after regional ischaemia in the rabbit heart in vivo, but the underlying mechanisms are unknown. Since adhesion molecules on neutrophils are closely involved in the pathophysiology of ischaemia/reperfusion injury and modulation of neutrophil function, we investigated the effect of xenon on neutrophil adhesion molecule expression in vitro. METHODS: Freshly isolated neutrophils were incubated with 30% or 60% xenon for 60 min. In unstimulated and after stimulation with either N-formyl-methionyl-leucyl-phenylalanine or phorbol-12-myristate-13-acetate neutrophil surface expression of PSGL-1, L-selectin, CD11a and CD11b were measured by flow cytometry. RESULTS: At both concentrations, xenon reduced the surface expression of PSGL-1 by 10% (P < 0.05), and of L-selectin by 15% (P < 0.05) in the 60% xenon group. Furthermore, N-formyl-methionyl-leucyl-phenylalanine activated neutrophils showed an increased removal of L-selectin from the neutrophil surface following incubation with xenon (30% compared to controls, P < 0.05). Neutrophil beta2-integrin expression was not altered by xenon. CONCLUSIONS: Xenon increases the removal of the selectins PSGL-1 and L-selectin from the neutrophil surface in vitro. Since both selectins are involved in the initial contact between neutrophils and endothelial cells, xenon may affect neutrophil adhesion to endothelium during ischaemia/reperfusion injury. However, because the beta2-integrin expression was unaffected by xenon, further investigations are required to clarify whether xenon may modulate neutrophil transmigration through endothelial cells in vivo.