Effects of N-acetylcysteine on human polymorphonuclear leukocytes.

N-acetylcysteine (NAC) at concentrations from 0.39 micrograms/ml to 100 micrograms/ml did not affect chemotaxis under agarose of human polymorphonuclear leukocytes (PMNLs). No reduction of phagocytic or bactericidal capacity was found in PMNLs exposed to NAC at the same concentrations. At high concentrations of NAC (25-100 micrograms/ml) a distinct inhibition of the chemiluminescent response to formylmetionyl-leucyl-phenylalanine (fMLP) known to be associated with mainly extracellular metabolic processes, was observed, consistent with the well known scavenger effects of the drug. The response to opsonized zymosan, which reflects mainly intracellular metabolic activity, was less marked. At a still higher concentration of NAC (500 micrograms/ml), a distinct effect on both intra- and extracellularly generated chemiluminescence could be demonstrated. The lack of inhibitory effects on phagocytosis and intracellular killing in spite of the effects on chemiluminescence indicates that NAC has no negative influence on the antimicrobial activity of PMNLs.