Quantitation of Human Granulocyte Protease Inhibitors in Non-Purulent Bronchial Lavage Fluids

Abstract

The predominant inhibitors of granulocyte proteases in plasma (α₁-antitrypsin, α₁-antichymotrypsin, and α₂-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 α₁-antitrypsin and α₁-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 α₁-antitrypsin and α₁-antichymotrypsin showed electrophoretic mobilities and molecular sizes similar to the native proteins but had no enzyme reactivity.