The effect of activated alveolar macrophages on experimental lung emphysema development. III. Morphological analysis of the lung tissue and alveolar macrophages in situ.

Morphological (in light and transmission electron microscope) as well as morphometrical analysis of the lungs was performed on experimental, papain-induced lung emphysema. Development of emphysematous changes was studied seven days after a single intratracheal instillation of papain solution. The effect of alveolar macrophages (AM) activation by BCG-vaccine on changes in pulmonary tissue was analyzed. In the rats given BCG the number of AM increased and demonstrated enhanced activity. Increase in reticulin fibre density in places of AM cumulation, particularly in BCG+papain-treated rats was observed. The lungs of animals treated with BCG+papain showed enhancing of emphysema comparing with the papain-treated rats. Development of emphysematous changes, especially in BCG+papain-treated rats coexisted with cumulation of activated alveolar macrophages and collagen fibres as well as type II alveolar epithelial cells proliferation. Our data support the inflammatory-repair hypothesis of emphysema pathogenesis and indicate that AM regulate collagen production in the lung. Type II alveolar epithelial cells seem be important in lung injury and repair.