Qualitative Studies of Lung Lavage α1-Proteinase Inhibitor

Abstract

A method is described which enables identification of the molecular size of .alpha.1 proteinase inhibitor (.alpha.1-PI) in biological fluids. This technique when applied to bronchoalveolar lavage fluids clearly demonstrates .alpha.1-PI in 3 molecular forms; the native molecule (Mr .apprxeq. 54,000), a partially proteolyzed form (Mr .apprxeq. 49,000) and in a form suggestive of a complex with enzyme (Mr .apprxeq. 82,000). Samples showing the presence of native .alpha.1-PI inhibited more porcine pancreatic elastase than samples where no native .alpha.1-PI was seen or where the predominant form was partially proteolyzed .alpha.1-PI (P < 0.001). Although the predominant band of .alpha.1-PI was more frequently the partially proteolyzed form in current smokers (P < 0.01), there was no clear difference in the inhibitory function of .alpha.1-PI between current smokers and nonsmokers and those with and without airflow obstruction.