Functional studies on iron-laden alveolar macrophages Part I. Functions of alveolar macrophages in lung diseases, especially arc welder's lung

Alveolar macrophages are essential components of pulmonary defense. They are unique among mononuclear phagocytes in having direct exposure to inhaled microorganisms and environmental toxins and in their metabolic adaptations to the aerobic environment. On the other hand, they are thought to have some properties common to all mononuclear phagocytes which constitute the reticuloendothelial system. Moreover, the ironladen alveolar macrophages seem to play a role in the induction of tissue injury and iron transport of the lung. In this experiment, the functions of alveolar macrophages, namely, chemotaxis, phagocytosis, β-galactosidase activity and superoxide production were studied in patients with arc welder's lung, other lung diseases and normal adults as controls. No significant difference was present in the chemotaxis of alveolar macrophages to zymosan activated serum between normal subjects and patients with arc welder's lung. The phagocytosis of opsonized zymosan particles by alveolar macrophages from patients with arc welder's lung was less than that of normal subjects. No significant difference was observed in the phagocytosis by alveolar macrophages between normal subjects and patients with lung diseases except for arc welder's lung. There was no significant difference in β-galactosidase activity of alveolar macrophages between normal subjects and patients with arc welder's lung. Superoxide production by alveolar macrophages from patients with arc welder's lung was significantly lower than of normal subjects. The observations reported here indicate that the functions of alveolar macrophages, especially phagocytosis and superoxide production, are suppressed in arc welder's lung.