Quantitation of human granulocyte protease inhibitors in non-purulent bronchial lavage fluids

The predominant inhibitors of granulocyte proteases in plasma (alpha1-antitrypsin, alpha1-antichymotrypsin, and alpha2-macroglobulin) were quantitated in unconcentrated bronchial lavage fluids obtained from non-infected individuals, together with the acid-stable low molecular weight inhibitor with activity against granulocyte elastolytic and chymotrypsin-like enzymes. This latter inhibitor accounted for about 90% of the total molar concentration of granulocyte protease inhibitors in the bronchial lavage fluids. The remaining 10% consisted mostly of alpha1-antitrypsin and alpha1-antichymotrypsin. About 85% of the bronchial inhibitor was in a free form with preserved enzyme reactivity. The remaining 15% of the immunoreactive bronchial inhibitor exhibited a molecular size indicating complexation with enzymes. The major portion of alpha1-antitrypsin and alpha1-antichymotrypsin showed electrophoretic mobilities and molecular sizes similar to the native proteins but had no enzyme reactivity.