The Journal of clinical investigation
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Bronchoalveolar lavage (BAL) fluid was obtained from 24 sequentially studied patients with adult respiratory distress syndrome (ARDS) for assessment of potential activating and mediating factors. Proteolytic activity of the fluids was observed by measuring cleavage of radiolabeled proteins of the contact (Hageman factor) and complement systems. Proteolytic activity was observed in 17 of 24 (71%) patients with ARDS, and BAL fluid of the 7 ARDS patients without demonstrable, active, enzyme exhibited inhibitory activity for the proteolytic activity. ⋯ Free, inactive alpha1-PI was also observed in these fluids. The data reveal that in BAL fluids from all 24 patients with ARDS, leukocytic elastase and/or alpha1-PI exist. A complex of elastase and alpha1-PI was observed in BAL fluids, and in some cases where active enzyme and alpha1-PI coexisted, free, but inactive alpha1-PI was present.