Phagocyte enzymes in bronchoalveolar lavage from patients with pulmonary sarcoidosis and collagen vascular disorders

The balance between proteases and antiproteases in the lower respiratory tract is believed to play a role in the outcome of interstitial lung diseases. In this cross-sectional study, we measure several phagocyte derived enzymes, namely plasminogen activator, neutrophil elastase and an ill-defined protease active on the trialanine chromophore substrate succinyl-alanine3-nitroanilide (SLAPN) in bronchoalveolar lavage (BAL) fluid from 42 patients with pulmonary sarcoidosis and from 43 patients with collagen vascular disease (CVD), 22 without lung disease (group I) and 21 associated with parenchymal lung disease (group II). The results show: a) that sarcoidosis is associated with increased plasminogen activator activity and with the presence of enzymatic activity against SLAPN corresponding at least in part to a metalloprotease; b) that CVD in the absence of radiographic lung disease is associated with an increase of plasminogen activator activity and increased levels of alpha 1-antiprotease-neutrophil elastase complexes; c) that the majority of untreated CVD (group II) patients have detectable levels of neutrophil elastase activity. These data show that patients with pulmonary sarcoidosis and CVD have different enzymatic profiles in their lower respiratory tract as assessed by BAL. Thus, sarcoidosis (mostly lymphocytic) is associated with enhanced macrophage-derived proteolytic activity in BAL, while CVD patients both with and without lung disease have increased neutrophil counts and neutrophil elastase complexed to alpha 1-protease inhibitor and presumably inactive in BAL. Finally, only BAL from untreated CVD patients with interstitial lung disease contain neutrophil elastase activity. This latter activity could contribute to the lung lesions frequently observed in these disorders.