Early changes after radiation exposure may serve as predictors as well as targets for alleviation of radiation-induced injury in the lung. The aim of our study was to examine alterations on the cell and tissue levels in the lung and blood changes of immunological and cytokines profiles induced by ionizing radiation (IR) during the first month after irradiation in the mice experimental model. Female C57BL/6 mice were total body irradiated (TBI) by 8 Gy. Lung tissue samples and blood and were collected 4, 8 and 24 h, 7, 21 and 30 d after TBI. We measured absolute cell counts, cell populations and cytokines profile in the blood and evaluated histopathological analysis in the lung, immunophenotypization of the main lung cell populations and cytokine profiles. In blood, the acute radiation syndrome developed with recovery being observed at 21 – 30 d, observed by hematological markers. In the lung tissue, a biphasic response occurred. At first, a significant decreased of lymphocytes, resident tissues macrophages and air/tissue ratio associated with increased neutrophils was observed at 8 – 24 h. Subsequently, increase in infiltrating CD4+ T-lymphocytes, neutrophils and resident tissues macrophages and decreased airiness were measured 21 and 30 d after TBI. In summary, our study describes the mechanisms that lung tissue enables to cope with non-lethal injury.

Keywords: ionizing radiation; radiation induced lung damage; radiation pneumonitis; latent phase; lymphocytes; cytokines