Effect of halothane and N2O on the oxidative activity of human neutrophils

The effect of clinically used concentrations of halothane and N2O on the microbicidal oxidative function of human neutrophils was investigated. Neutrophil oxidative activity was assessed utilizing the method of luminol dependent chemiluminescence (LDCL) by particulate (opsonized zymosn) and nonparticulate (phorbol myristate acetate, [PMA]) stimulated cells. In vivo exposure of neutrophils to 2 and 3% halothane resulted in a 13 and 40% inhibition, respectively of the air-exposed LDCL response with zymosan-activated neutrophils; 1% halothane had no effect. Similar results were seen with PMA-stimulated neutrophils. N2O 80% did not inhibit the LDCL response, and also did not show an additive inhibition when combined with halothane. Although th halothane inhibition of LDCL was reversible (equal to control, no anesthetic, LDCL responses following exposure to air), neutrophils treated with N2O plus halothane and then exposed to air for 30 min showed a significantly higher LDCL response over the control experiments. The inhibition of zymosan- or PMA-stimulated neutrophil LDCL by halothane suggests either a membrane perturbation or a direct inactivation of oxidative enzyme(s) by the anesthetic. This impairment of oxidative activity may partly explain the reduced bacterial killing by neutrophils seen after exposure to halothane.