The comparative study of reactive oxygen species generated by polymorphonuclear leukocytes as alpha 1-proteinase inhibitor inactivators-possible application for antioxidant prevention of emphysema.

The oxidative inactivation of alpha 1-proteinase (alpha 1AP) inhibitor is a one of mechanisms that may lead to the pulmonary emphysema. This process is caused by oxidants derived from atmosphere and released from lung phagocytes. These cells produce various oxidants hydrogen peroxide (H2O2), hypochlorous acid (HClO), hydroxyl (OH.) and superoxide (O2-) radicals after inflammatory stimulation. In this study I have investigated the effects of H2O2 (1.5 x 10(-5) to 1.5 x 10(-2) M) alone or with addition of FeCl2 (50 microM) in order to generate OH., chloramine-T (1.5 x 10(-5) to 1.5 x 10(-3) M) which generates HClO, glucose 10 mg/ml-glucose oxidase (12.5 to 80 mU/ml)-H2O2 generating system, xanthine 0.2 mM-xanthine oxidase (12.5 to 80 mU/ml)-O2-2 generating system on the elastase inhibitory activity of alpha 1AP in vitro. H2O2 was weak in alpha 1AP inactivation--only concentration of H2O2 1.5 x 10(-2) caused severe loss of its activity to 23 +/- 8% inhibition of elastase. Addition of FeCl2 to H2O2 and following OH. generation did not enhance its alpha 1AP inactivation. O2-2 generating system inhibited moderately alpha 1AP. The % inhibition of elastase at concentration of xanthine oxidase 80 mU/ml was 65 +/- 7. HClO was most effective as an alpha 1AP inactivator. All used chloramine-T concentrations completely suppressed alpha 1AP activity. The obtained results and in vivo consumption of H2O2 by polymorphonuclear leukocyte myeloperoxidase for HClO production suggest that scavenging of these reactive oxygen species may be useful in prevention of emphysema.