Mechanism of radiation-induced apoptosis of human peripheral T cells

导致T淋巴细胞高水平放射敏感性的机制尚未得到充分的描述。在我们之前的研究中，我们证明了人类外周T淋巴细胞分别在5 Gy照射后13和24 h出现早期凋亡变化（膜联蛋白v阳性）和晚期凋亡变化（碘化丙啶阳性）。5gy辐照后10 h观察线粒体膜电位的变化。线粒体细胞色素c释放随线粒体膜电位变化而变化。为了阐明线粒体膜电位变化之前发生的机制，我们检测了10 MV x射线照射对人外周血T淋巴细胞诱导的氧化DNA损伤的剂量和时间。结果，8-氧鸟嘌呤的产生，即DNA氧化损伤的产物，分别在辐照后10、6和3小时，2、5和20 Gy时被清楚地识别出来。

The mechanism leading to the high level of radiosensitivity of T lymphocytes has not yet been fully described. In our previous study, we demonstrated that human peripheral T lymphocytes revealed early apoptotic changes (annexin-V-positive) and late apoptotic changes (propidium iodide-positive), at 13 and 24 h after irradiation of 5 Gy, respectively. Changes in mitochondrial membrane potential were observed at 10 h after irradiation of 5 Gy. Mitochondrial cytochrome c release was confirmed following the changes in mitochondrial membrane potential. In order to elucidate the mechanism which occurs prior to the mitochondrial membrane potential changes, we examined the radiation dose and the timing of oxidative DNA damage induced in human peripheral T lymphocytes following 10 MV X-ray irradiation. As a result, the production of 8-oxoguanine, i. e., the product of oxidative DNA damage, was clearly identified starting at 10, 6, and 3 h, after 2, 5, and 20 Gy of irradiation, respectively.