Warenius H M, Down J D
Department of Medicine, University of Liverpool, UK.
Int J Radiat Biol. 1995 Dec;68(6):625-9. doi: 10.1080/09553009514551631.
We compared apoptosis in mouse thymocytes following exposure to low doses of high linear energy transfer (LET), 62.5-MeV (p-->Be+) fast neutrons and low LET, 4-MeV photons by flow cytometric analysis of hypodiploid cells. The incidence of apoptotic cell death rose steeply at very low radiation doses reaching a plateau of 3 Gy. Both the time course and the radiation dose-response curves were similar for high and low LET radiation modalities. The relative biological effectiveness (RBE) of 1.0 for apoptosis in the mouse thymocyte system contrasts with the much higher value typically seen in many classical systems of clonogenic cell survival and tissue response. This difference suggests that while radiation-induced apoptosis may contribute significantly to loss of susceptible cells at doses of < or = 2 Gy, it appears to have a questionable role in determining the relative intrinsic radiosensitivity of mammalian cells to high and low LET irradiation at clinically relevant levels of cell kill.
我们通过对亚二倍体细胞进行流式细胞术分析，比较了小鼠胸腺细胞在暴露于低剂量高传能线密度（LET）的62.5 MeV （p→Be+）快中子和低LET的4 MeV光子后的细胞凋亡情况。在非常低的辐射剂量下，凋亡细胞死亡的发生率急剧上升，在3 Gy时达到平台期。高LET和低LET辐射模式的时间进程和辐射剂量反应曲线相似。小鼠胸腺细胞系统中凋亡的相对生物效应（RBE）为1.0，这与许多经典的克隆形成细胞存活和组织反应系统中通常看到的高得多的值形成对比。这种差异表明，虽然辐射诱导的凋亡在剂量≤2 Gy时可能对易感细胞的损失有显著贡献，但在临床相关细胞杀伤水平上，它在确定哺乳动物细胞对高LET和低LET辐射的相对固有放射敏感性方面的作用似乎值得怀疑。
