Alveolar cells in cyclophosphamide-induced lung injury. An ultrastructural analysis of type II alveolar epithelial cells in situ.

Recent studies have brought rich evidence in favour of the significant contribution of the surfactant system-forming structures to morphogenesis of many pulmonary disorders. The aim of this study was to evaluate the effect of intraperitoneal cyclophosphamide administration on changes within this system. The experiments used 40 Wistar rats, of 170 g body weight. The animals were divided into two experimental groups. Group I animals were given cyclophosphamide (Endoxan-ASTA) in a single intraperitoneal dose of 150 mg/1 kg b.w./1 ml PBS/. Group II (control) received 1 ml PBS. All the animals were sacrificed after 1, 3, 7 and 28 days following intraperitoneal cyclophosphamide or PBS administration. Morphological examinations of pulmonary tissue were based on ultrastructural analysis in the transmission electron microscope. The study revealed that a single intraperitoneal cyclophosphamide injection caused damage to all elements forming the surfactant system, particularly to type II alveolar epithelial cells. Rebuilding processes in pulmonary tissue, coexisting with destructive changes, occurred with a significant contribution of type II alveolar epithelial cells. These cells are likely to take an active part in pulmonary fibrosis processes observed after the action of cyclophosphamide.