Researches on the regenerating thymus after irradiation-to find out the responsible factors which may regulate the thymic epithelial cell regeneration

(1)照射大鼠胸腺，进行形态学检查。与6 Gy照射相比，8 Gy照射下胸腺细胞的恢复速度较慢。尽管从6gy和8gy辐射恢复时胸腺的结果是相似的。(2)在大鼠表皮未成熟上皮细胞中特异性检测到P63分子。在正常大鼠胸腺中，p63分子是零星存在的，尤其是在囊下区域。照射后胸腺上皮细胞p63阳性的相对数量增加。提示辐照后，胸腺内不仅胸腺细胞被破坏，胸腺上皮细胞也被破坏，除胸腺细胞突然再生外，甚至胸腺上皮细胞也可能发生再生。不同剂量的照射对胸腺上皮细胞的损伤程度不同，随后在照射后和再生过程中，胸腺上皮细胞可能发生一些不可逆的变化，导致8Gy照射下胸腺重量仅恢复65%。(3) 6 Gy辐照胸腺与8 Gy辐照胸腺细胞因子信息表达不同。特别是，与6 Gy胸腺相比，8Gy胸腺中Il-6的信息水平显著降低。在辐照恢复时间测量这些信息。(4)将培养的原代胸腺上皮细胞分别以6 Gy和8 Gy的辐照剂量体外诱导胸腺细胞分化。然而，从我们的实验来看，在6 Gy和8 Gy辐照之间没有观察到统计学上的显著差异。

(1)Rats were irradiated and the thymus was examined morphologically. Comared to the 6 Gy irradiation, in the case of 8 Gy irradiation, the recovery of thymocytes was slower. although the findings in the thymus at the time of recovery from both 6 Gy and 8 Gy irradiations were similar.(2)P63 molecule can be detected specifically in the immatrure epithelial cells in the rat epidermis. In the normal rat thymus, p63 molecules were detected sporadically, especially in the region of the subcapsular area. After irradiation, the relative number of p63 positive thymic epithelial cells increased in number. These suggest that after irradiation, in the thymus, not only the thymocyte but also the thymic epithelial cell were destroyed and in addition to the abrupt thymocyte regeneration, even regeneration of the thymic epithelial cells may take place. Following the different doses of irradiation, the degree of the damages on the thymic epithelial cells may be different and subsequently, after irradiation and on the process of regeneration, some irreversible changes may be induced on the thymic epithelial cells and resulted in only 65% of recovery in the thymus weight in the 8Gy irradiation.(3)The cytokine message expressions were different between 6 Gy and 8 Gy-irradiated thymi. Particularly, the message levels for Il-6 were significantly low in the 8Gy irradiated thymus compared to those in 6 Gy irradiated thymus., when the messages were measured at the recovered time from the irradiation.(4)The primary cultured thymic epithelial cells, which were irradiated at the irradiation doses of either 6 Gy or 8 Gy were used for induction of thymocyte differentiation in vitro. However, from our experioments statistically significant differences were not observed between 6 Gy and 8 Gy irradiation.