The effect of the anaesthetic agent isoflurane on the rate of neutrophil apoptosis in vitro

Background. Volatile anaesthetic agents influence neutrophil function, and potentially, the inflammatory response to surgery. Aim. The objective of this study was to determine the effect of isoflurane (1-4%) on human polymorphonuclear neutrophil apoptosis in vitro. Methods. Venous blood from 12 healthy volunteers was exposed to 0, 1, and 4% isoflurane delivered via a 14G Wallace flexihub internal jugular cannula, at a fresh gas flow of 0.5l/min for 5 minutes. Isolated neutrophils were assessed for apoptosis at 1, 12, and 24 hours in culture using dual staining with annexin V-FITC and propidium iodide (Annexin-V FITC assay). Data were analysed using paired, one-tailed Student's t-tests. p<0.05 was considered significant. Results. At 1 hour apoptosis was inhibited in the 1% (5.1 [6.8]%; p=0.017) and 4% (4.8 [4.5]%; p=0.008) isoflurane groups compared to control (11.3 [6.9]%). At 12 and 24 hours, a dose-dependent inhibition of apoptosis was demonstrated, i.e. 4% > 1% > 0%. Conclusion. Human neutrophil apoptosis is inhibited in a concentration-dependent manner in vitro by isoflurane in clinical concentrations.