Thiopentone and propofol, but not methohexitone nor midazolam, inhibit neutrophil oxidative responses to the bacterial peptide FMLP.

The effects of different anaesthetics on the neutrophil oxidative response in vitro are compared. Neutrophils were stimulated with small amounts of the bacterial peptide N-formyl-L-methionyl-L-leucyl-phenylalanine as a physiological, receptor-dependent stimulus. A new flow cytometry-based method capable of detecting the small amounts of H2O2 generated by neutrophils in a heterogeneous all-or-none response following submaximal stimulation with N-formyl-L-methionyl-L-leucyl-phenylalanine was used. Propofol and thiopentone suppressed the respiratory burst significantly (P < 0.05 and P < 0.01) in therapeutic concentrations, while midazolam and methohexitone inhibited significantly (P < 0.01) only at concentrations greater than the therapeutic range. Impairment of the neutrophil response was primarily because of a reduction in the number of neutrophils participating in the respiratory burst and not of a proportional decrease of the fluorescence of all neutrophils.