The mucosal defence capacity against proteolytic leukocyte enzymes.

Proteolytic enzymes are released from granulocytes in connection with normal turnover and phagocytosis. Interest has been focused on granulocyte elastase as it has been shown to be associated with the development of lung emphysema. Elastase is present in purulent bronchial secretions where it is the dominating cause of elastolytic activity. The dominating inhibitors of elastase in the respiratory tract are alpha 1-antitrypsin and antileukoprotease. Antileukoprotease, which seems to be locally produced, is a potent inhibitor of elastase and accounts for about 90% of the inhibiting capacity against elastase. A local protective function of antileukoprotease is suggested by the finding that antileukoprotease was bound to granulocyte elastase in purulent bronchial secretions. The function of alpha 1-antitrypsin and antileukoprotease is reduced by the addition of smoke condensate in a dose- and time-dependent way. Smoke condensate was also found to depress the enzymatic activity of granulocyte elastase. Further studies of the protease-antiprotease balance in bronchial secretions from smokers with and without airway disease are necessary before any conclusions can be drawn regarding the pathophysiological significance of these results.