Changes in alveolar macrophage enzyme content and activity in smokers and patients with chronic obstructive lung disease

An influx of polymorphonuclear and mononuclear cells into the lungs of smokers and patients with chronic obstructive lung disease (COLD) is thought to be an important factor in the development of pulmonary emphysema. Next to the synthesis and release of toxic oxygen radicals and mediators, an enhanced production and activity of proteolytic enzymes could play an important role in the pathogenesis of emphysema. In the present study changes were investigated in the broncho-alveolar lavage (BAL) fluid and BAL-cells, especially in alveolar macrophages. Pulmonary lavages were performed in the middle lobe with sterile saline of 37 degrees C in individuals, who could be divided on the basis of their history and lung function into normal/nonsmokers, normal/smokers, COLD-patients/nonsmokers and COLD-patients/smokers. Alveolar macrophages obtained by BAL were stained for different lysosomal enzymes. Isolated BAL-fluid and BAL-cells were assayed for elastolytic activity. In alveolar macrophages of smoking COLD-patients significantly more beta-glucuronidase could be demonstrated. Elastolytic activity changed with smoking habits, suggesting an enhanced release of elastolytic enzymes. No correlation was found between elastolytic activity and the amount of polymorphonuclear cells in the BAL-fluid. From these results it may be concluded that enzymes from alveolar macrophages play a more important role in the pathogenesis of emphysema than those from polymorphonuclear cells.