Functional and immunoreactive alpha 1 proteinase inhibitor in bronchoalveolar lavages: methodological studies

The functional activity of alpha 1 proteinase inhibitor (alpha 1PI) in bronchoalveolar lavages (BAL) was determined with an automated method, using its inhibitory capacity against porcine pancreatic elastase. Immunoreactive alpha 1PI was measured by immunonephelometry-laser (INL). These two methods may generally be applied on unconcentrated samples. Precision and accuracy of both methods are studied. INL was preferably used to electroimmunodiffusion (EID) because it gave unchanged values after alpha 1PI had reacted with proteases. In BAL, for some specimens, the alpha 1PI content evaluated by EID was underestimated with respect to its measurement by INL. The degree of underestimation is related to the presence of non-functional forms of alpha 1PI.