[The role of human neutrophil elastase in the development of human emphysema]

It has been proposed that the development of human emphysema is related to an imbalance between elastase and its inhibitors in the lung. This report describes the immunolocalization of human neutrophil elastase (HNE) in the alveolar interstitium of 6 patients with emphysema by using immunohistochemical, ultrastructure technique. The results showed that HNE is localized in the azurophil granules of neutrophils, and extracellularly on the elastic fibers of alveolar interstitium and basement membranes of epithelium and endothelium in four emphysematous lungs with chronic bronchitis. The damage of elastic fibers and basement membranes can also be observed. The HNE level of the alveolar interstitium is obviously elevated and closely related to the severity of emphysematous lesions by measuring mean linear intercept (MLI), with the correlation coefficient r = 0.84. This suggests HNE can bind to elastic fibers and basement membranes in the emphysematous lung, and damage these tissues, which might play an important role in the development of human emphysema. These findings support the elastase-antielastase imbalance hypothesis concerning the pathogenesis of human emphysema.