Regulation by the antioxidants ascorbate, cysteine, and dapsone of the increased extracellular and intracellular generation of reactive oxidants by activated phagocytes from cigarette smokers.

The bimodal pattern of N-formyl-methionyl-leucyl-phenylalanine (FMLP)-activated luminol-enhanced chemiluminescence with distinct early (occurring within 1 min) extracellular and late intracellular oxidative responses was compared in polymorphonuclear leukocytes (PMNL) from asymptomatic cigarette smokers and nonsmoking control subjects. Relative to control PMNL, the PMNL from smokers were hyperreactive to FMLP stimulation with increased generation of both extracellular (p less than 0.025) and intracellular (p less than 0.025) reactive oxidants. Smokers' PMNL also showed increased PMNL-activated superoxide generation and increased apparent receptors for FMLP. The water-soluble antioxidants ascorbate and cysteine (2.5 X 10(-5) M to 2.5 X 10(-4) M) selectively neutralized the extracellular activity of PMNL-derived reactive oxidants. The lipid-soluble antioxidant dapsone (1.25 to 30 micrograms/ml), on the other hand, inhibited both the extracellular and intracellular FMLP-activated chemiluminescence responses in PMNL from smokers and nonsmoking control subjects. Regulation of the increased extracellular and intracellular membrane-associated oxidative responses in PMNL from cigarette smokers is probably an important function of water-soluble and lipid-soluble antioxidants in vivo.