Studies on the role of antileukoprotease in respiratory tract diseases.

Antileukoprotease, an inhibitor of granulocyte elastase, was studied in paired sera from 19 patients with pneumonia and from 9 patients with cholecystolithiasis. The circulating level of antileukoprotease was significantly higher in patients with pneumonia compared with patients with cholecystolithiasis. In the latter group, surgery raised the level of general acute phase reactants, but did not affect the level of antileukoprotease. In sera from patients with pneumonia, antileukoprotease was recovered in a free and active form, as shown by gel-filtration of sera before and after the addition of leukocyte elastase. A local protective function of antileukoprotease is suggested by the finding that antileukoprotease was bound to granulocyte elastase in purulent bronchial secretions.