Bronchoalveolar lavage findings of radiation induced lung damage in rats

Radiation induced lung damage is a main dose limiting factor when irradiating the thorax. Although Bronchoalveolar lavage (BAL) is a valuable tool for studying the mechanisms in pulmonary disorders, there are only a few studies about the BAL findings of radiation-induced lung damage. We evaluate the BAL findings for the evaluation of radiation-induced lung damage. Sprague-Dawley rats received 20 Gy of radiation to the right lung and control group were sham irradiated. BAL was performed for the right and left lungs separately 3, 7, 14, 28, and 56 days after radiation. The cells in the BAL fluid were counted and the concentrations of protein, NO, and TGF-beta in the BAL fluid were measured. Lung tissues were removed after BAL and stained with hematoxylin-eosin (H-E) and trichrome. From 2 weeks, histological findings showed definite lung damage. The protein level and TGF-beta in BAL fluid from the irradiated lung peaked at 4 and 8 weeks, respectively, after radiation. Total cell count in BAL fluid from both sides of lungs was increased from 2 weeks and continued to increase at 8 weeks after irradiation. NO in BAL fluid from both sides of lungs peaked at 4 weeks after irradiation. The protein level and TGF-beta were increased in BAL fluid from irradiated lungs. However, alveolar cells and NO increased in BAL fluid from both irradiated and non-irradiated lungs. BAL is a valuable tool for the evaluation of radiation induced lung damage.