Ozone Effects on Alpha-1-Proteinase Inhibitor in Vivo: Blood Plasma Inhibitory Activity Is Unchanged

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Abstract
The possible oxidative inactivation of buman blood plasma alpha-1-proteinase inhibitor (α-l-Pl) by inhaled ozone was assessed. Eleven male volunteers (non-smokers) were exposed to 0.5 ppm ozone for four bours on two consecutive days and ten control subjects were exposed to air under the same conditions. Blood plasma samples, drawn before and after treatment, were assayed for total α-l-PI, total protein and elastase inbibitory activity. The amount of active α-l-PI in plasma samples was quanti-tated by titrating porcine pancreatic elastase with increasing amounts of plasma. The importance of constructing titration curves for determinations of this type was demonstrated. No differences were noted in the ratios of total α-1-PI/total protein or elastase inhibitory activity/total α-l-PI in the plasma from ozone exposed individuals relative to controls. Although inhaled ozone did not result in any significant decrease in the activity of blood plasma α-l-PI, these findings do not preclude the possibility of oxidative inactivation of a α-l-Pl in the lung.