Superoxide formed from cigarette smoke impairs polymorphonuclear leukocyte active oxygen generation activity

Reactive free radicals contained in cigarette smoke (CS) and compromised phagocytic antimicrobial activities including those of polymorphonuclear leukocytes (PMNs) have been implicated in the pathogenesis of severe CS-related pulmonary disorders. In CS-exposed buffer solutions, O₂ ^{{dot minus}} was the predominant generated reactive oxygen species, as demonstrated by lucigenin-amplified chemiluminescence and electron spin resonance (ESR) spin-trapping with 5,5-dimethyl-1-pyrroline N-oxide (DMPO). When PMNs were incubated in this buffer, phorbol 12-myristate 13-acetate (PMA)-stimulated active oxygen production and coupled O₂ consumption were strongly impaired without appreciably affecting PMN viability (1-min exposure inhibited active oxygen production by 75%). Superoxide dismutase (SOD) totally protected and an iron chelator, diethylenetriaminepentaacetic acid (DETAPAC), also protected the CS-exposed PMNs, suggesting that generated O₂ ^{{dot minus}} was an initiating factor in the impairment and OH · generation was a subsequent injurious factor. Pretreatment of PMNs with antioxidants such as α-tocopherol and dihydrolipoic acid (DHLA) was partially protective. The results suggest that (i) O₂ ^{{dot minus}} is probably generated in the upper and lower respiratory tract lining fluid when they come in contact with CS; (ii) such generated O₂ ^{{dot minus}} can primarily impair PMN capabilities to generate reactive oxygen species; and (iii) since these effects may contribute to the pathogenesis of CS-related lung diseases, prior supplementation with antioxidants such as α-tocopherol or DHLA might be successful in preventing these deleterious effects.