Effect of sodium benzoate on polymorphonuclear leukocyte function.

Sodium benzoate is widely used as a food preservative and reputed to be a scavenger of hydroxyl radical (.OH). The effects of sodium benzoate on the function of polymorphonuclear leukocytes (PMN) stimulated by S. aureus or the chemical agent, phorbol myristate acetate (PMA) were examined in vitro using assays of chemiluminescence (CL), total bactericidal activity, intracellular recovery of bacteria, as well as release of lactate dehydrogenase (LDH), lysozyme and superoxide anion (O2(-)). Sodium benzoate decreased chemiluminescence, superoxide anion and lysozyme release by PMN stimulated with S. aureus but did not similarly affect these responses of PMN to the chemical agent, PMA. The ability of PMN to kill S. aureus was also impaired by sodium benzoate and associated with a reduced number of intracellular bacteria recovered after 90 minutes incubation. LDH release from PMN was not demonstrable at concentrations of sodium benzoate below 100 mM indicating that damage can not account for these findings. The underlying mechanism of the altered bactericidal function of PMN treated with sodium benzoate appears to be a result of decreased uptake of S. aureus.