Neutrophil elastase: alpha-1-proteinase inhibitor complex in serum and bronchoalveolar lavage fluid in patients with pulmonary fibrosis.

It was hypothesized that neutrophil elastase released from activated neutrophils may play an important role in the pathogenesis of pulmonary fibrosis. In the present study, we measured the neutrophil elastase:alpha-1-proteinase inhibitor complex (E-PI) in serum and bronchoalveolar lavage fluid (BALF) in 26 patients with pulmonary fibrosis and evaluated the correlation between E-PI levels and several parameters. E-PI levels in serum of patients with pulmonary fibrosis (635.8+/-112.0 ng.mL(-1)) were significantly elevated compared to normal nonsmokers (122.0+/-4.0 ng.mL(-1)) as well as normal smokers (132.8+/-8.4 ng.mL(-1)) (p<0.01). E-PI levels in serum significantly correlated with hepatocyte growth factor (HGF) levels in serum, C-reactive protein (CRP), and negatively correlated with arterial oxygen tension (Pa,O2), and arterial carbon dioxide tension (Pa,CO2). E-PI/albumin levels in BALF significantly correlated with HGF/albumin levels in BALF, lactate dehydrogenase (LDH)/albumin in BALF, total number of inflammatory cells (alveolar macrophages and neutrophils) in BALF, and several markers derived from epithelial cells in BALF. Our data demonstrated: 1) neutrophil elastase:alpha-1-proteinase inhibitor complex in serum increased in patients with pulmonary fibrosis; and 2) neutrophil elastase:alpha-1-proteinase inhibitor complex in serum and bronchoalveolar lavage fluid correlated with clinical parameters in pulmonary fibrosis. These results suggest that neutrophil elastase may play a significant role in the process of lung injury in pulmonary fibrosis.