HISTOGENESIS OF ABNORMAL ELASTIC FIBERS IN BLEBS AND BULLAE OF PATIENTS WITH SPONTANEOUS PNEUMOTHORAX - ULTRASTRUCTURAL AND IMMUNOHISTOCHEMICAL STUDIES

Elastic fibers in 15 blebs and 17 bullae with spontaneous pneumothorax were studied by means of electron microscopy and light and electron m icroscopic immunohistochemistry for elastin and alpha(1)-antitrypsin. Blebs were formed in association with focal organized alveoli, and bul lae were formed in association with pulmonary emphysema. Both blebs an d bullae had abnormal elastic fibers. Ultrastructurally, abnormal elas tic fibers of blebs and bullae consisted of accumulated thick and fine fibers. Accumulated thick elastic fibers showed vacuolar changes and electron-dense granular deposits, and they were associated with spiral ing collagen fibrils. These thick elastic fibers reacted evenly with a ntielastin antibody and also reacted with anti-alpha(1)-antitrypsin an tibody. They are thought to be degraded elastic fibers. Accumulated fi ne elastic fibers consisted of bundles of microfibrils and granular am orphous components, and they reacted with anti-elastin and anti-alpha( 1)-antitrypsin antibody. These fine elastic fibers are thought to be n ot only newly formed in the process of organization but also degraded. It is suggested that elastic fibers of blebs and bullae are degraded due to an imbalance between elastase and alpha(1)-antitrypsin.