Introduction
Naloxone has been proposed to treat septic shock. We assessed by flow cytometry its effect in vitro on phagocytose (PH) and burst oxidation (BO) of neutrophils and monocytes after various stimuli in 10 healthy volunteers.
Methods
Whole blood was incubated with or without naloxone at a range of concentrations used in septic shock (2 × 10-4, 2 × 10-5, 2 × 10-6, 2 × 10-7 M). We added dihydrorhodamine 123 to mark H2O2 production. We stimulated the cells by either propidium iodide stained S. aureus, E. coli or C. albicans, or by phorbol-myristate-acetate (PMA). We used an index of PH and an index of BO. As H2O2 production depends on PH and on BO, wedefined a global index (GI) of its final production taking those two parameters into account.
Results
See Table 1: percentage of change in GI, BO and PH with naloxone compared with no naloxone after stimulation (Wilcoxon signed rank test).
Table 1.
| Naloxone | ||||
|---|---|---|---|---|
| 2 × 10-4 M | 2 × 10-5 M | 2 × 10-6 M | 2 × 10-7 M | |
| Neutrophils:S. aureus: GI(BO/PH) | -72**(-9°/-69**) | -51**(+31°/-56**) | -24**(+20*/-39*) | -14(+29*/-37**) |
| Neutrophils:E. coli: GI(BO/PH) | -90**(-30°/-90°) | -72**(+11°/-80**) | -25**(+5°/-43*) | -18**(+109°/-40**) |
| Neutrophils:C. albic: GI(BO/PH) | -51**(-46**/-10*) | -35**(-31**/-7°) | -23°(-10*/-2°) | -8°(+2°/-12°) |
| Monocytes:S. aureus: GI(BO/PH) | -58**(-75**/+55*) | -51**(-57**/27°) | -32**(-24*/-10°) | -35*(-13°/-18*) |
| Monocytes:E. coli: GI(BO/PH) | -22°(-73**/+158**) | -45**(-65**/+43**) | -35*(-31*/-4°) | -25°(-19°/-22°) |
| Monocytes:C. albic: GI(BO/PH) | -58**(-63**/+1300°) | -34**(-37**/+833°) | -3°(-10*/+21°) | +8°(+5°/+14°) |
| Neutrophils/monocytes: PMA: BO | -70*/-83* | -61*/-61* | -44*/-43* | -49*/-44* |
*P < 0.05; **P < 0.01; ° not significant.
Conclusion
Naloxone inhibits significantly in a dose-dependant manner theproduction of H2O2 in both neutrophils and monocytes atconcentrations used in septic shock, but its influence on PH and BO is different according to the applied stimulus.