Antileukoprotease-containing bronchiolar cells. Relationship with morphologic disease of small airways and parenchyma.

Twenty-seven surgically removed lungs and lobes were studied to assess the relation between the abundance of bronchiolar epithelial cells containing antileukoprotease (ALP) (ALP-pos/mm) and the degree of small airways disease (SADscore) and emphysema (destructive index = DI, and number of normal alveolar attachments on membranous bronchioles = normal AA/min). Between subjects, ALPpos/mm correlated with SADscore in membranous bronchioles (rs = 0.75; p less than 0.001) and with normal AA/mm (rs = -0.38; p = 0.05). Evaluation within each subject revealed significant correlations of ALPpos/mm with SADscore in membranous as well as in respiratory bronchioles (p less than 0.001), and also with normal AA/mm (p = 0.005). In membranous and in respiratory bronchioles, ALPpos/mm correlated significantly with the ALP concentration in homogenized tissue, as measured by ELISA (rs = 0.55 and 0.57, respectively; p less than 0.01). It is concluded that disease in small airways and destruction of their alveolar attachments are associated with a rise of the number of ALP-containing epithelial cells. We hypothesize that this cellular increase is part of the general defense against inflammatory and destructive processes in distal human airways, leading to higher levels of proteinase inhibitor in order to minimize tissue damage.