[en] Objective: To investigate the ability of Shenqi Fuzheng Injection on release of TGF-β₁ mRNA in human lung adenocarcinoma GLC-82 cells by ionizing radiation in vitro, and find the regulation mechanism to reduce the radiation-induced lung injury by traditional Chinese drug. Methods: GLC-82 cells were cultured in media with serum containing 1.563 mg/ml Shenqi Fuzheng Injection, then TGF-β₁ mRNA after exposure to different irradiation doses(O, 20, 30, 40 Gy) and time intervals (12,24,48 h) were investigated. The expression of TGF-β₁ mRNA detected semi-quantitatively by RT-PCR. Results: For the different irradiation doses group, TGF-β₁ expression were increased after irradiation, which was significantly elevated at 20 Gy compared with unirradiated cells. The GLC-82 cells, treated by Shenqi Fuzheng Injection, revealed a minor radiation mediated TGF-β₁, response on mRNA level, which was significantly different at 20 Gy compared with the irradiated group (P<0.05). For the different time intervals group, following irradiation exposure in 20 Gy, the TGF-β₁ mRNA levels in cells, which were treated by Shenqi Fuzheng Injection, were down-regulated and significantly decrease at 48 h (P<0.01). Conclusions: The transforming growth factor beta 1-TGF-β₁ is a key mediator for the pathogenesis of radiation-induced lung injury. Shenqi Fuzheng Injection down-regulates the radiation- induced TGF-β₁ release, and it might reduce the lung toxicity after thoracic irradiation. (authors)