Studies on alveolar macrophage function in interstitial lung disease Part 1. Abnormalities of alveolar macrophage functions

Interstitial lung diseases comprise a heterogeneous group of disorders that are characterized by the chronic accumulation of inflammatory and immune effector cells within the alveoli, where they produce alveolitis, granulomas, or fibrosis. To investigate the pathogenesis of these diseases, the fucntions of alveolar macrophages recovered from bronchoalveolar lavage were evaluated in patients with interstitial lung disease in comparison to healthy controls. Thirty six patients were investigated : 18 with sarcoidosis, 6 with idiopathic interstitial pneumonia (IIP), 5 with interstitial pneumonia associated with collagen vascular disease (IP-CVD), and 7 with hypersensitivity pneumonitis (HP). Both the chemotactic and phagocytic indices were significantly higher in the patients with sarcoidosis, IIP, and HP than in the healthy subjects. However, the patients with IP-CVD had a lower phagocytic index than the normal subjects. Acid phosphatase activity was lower in patients with IIP, IP-CVD, and HP compared with the healthy subjects, while beta-galactosidase activity was lower in patients with sarcoidosis and IP-CVD compared with the normal controls. Analysis of surface markers showed that CD15-positive macrophages were increased in patients with sarcoidosis, IIP, and HP, but there were no differences in CD14- and HLA-DR-positive macrophages in these patients when compared to the healthy subjects. These findings indicate that the recruitment of peripheral blood monocytes to the lungs is increased in patients with sarcoidosis, IIP, and HP. Alveolar macrophages may play an important role in the pathogenesis of intersitial lung disease