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目的:已知射线能引起免疫系统损伤,为此观察急性大剂量γ射线照射后小鼠外周血淋巴细胞的凋亡机制及与免疫功能的关系。方法:用原位末端标记、原位杂交和碱磷酶免疫组化技术观察急性大剂量γ射线照射小鼠外周血淋巴细胞凋亡特征,bax,bcl-2和bcl-XL的表达及T细胞亚群的变化。结果:①照射后,白细胞数迅速下降。而淋巴细胞凋亡率持续升高,7d达到峰值,12个月仍未恢复到正常值。照后24h在6～12Gy范围内呈较好的剂量效应关系,≥15Gy照射后凋亡率降低。②6Gy照后24h,淋巴细胞Bax蛋白表达即出现升高,当剂量为12Gy时达到峰值,≥15Gy照射后出现降低;而Bcl-2和Bcl-XL蛋白表达在照后24h明显下降,于12Gy照射后降至最低。Bax和Bcl-2mRNA的表达显示出相似的变化趋势。③照后3d,随照射剂量的增加T细胞及其亚群急剧降低,呈较好的剂量效应关系。结论:≤12Gy照射后细胞凋亡是淋巴细胞的主要死亡方式。照射后Bax的上调及Bcl-XL的下调在急性大剂量照射引起的淋巴细胞凋亡和免疫调控中起重要作用。
OBJECTIVE: It is known that radiation can cause damage to the immune system. To investigate the mechanism of apoptosis of peripheral blood lymphocytes and its relationship with immune function after acute and high dose γ-ray irradiation. Methods: The apoptosis characteristics of peripheral blood lymphocytes, the expression of bax, bcl-2 and bcl-XL and the expression of T cells in acute high dose γ-ray irradiation mice were observed by in situ end-labeling, in situ hybridization and alkaline phosphatase immunohistochemistry Subsets change. Results: ① After irradiation, the number of white blood cells decreased rapidly. The apoptosis rate of lymphocytes continued to rise, reached its peak on the 7th day and remained unchanged at 12 months. 24h after irradiation in the range of 6 ~ 12Gy showed a good dose-response relationship, 15Gy irradiation after the apoptosis rate decreased. (2) The expression of Bax protein in lymphocytes increased at 24h after 6 Gy irradiation, peaked at 12 Gy, decreased after ≥15 Gy irradiation, while the expression of Bcl-2 and Bcl-XL decreased significantly at 24h after irradiation, After the lowest. The expression of Bax and Bcl-2 mRNA showed a similar trend. ③ After 3d, the T cells and their subpopulations decreased sharply with the increase of irradiation dose, showing a good dose-response relationship. Conclusion: Apoptosis after ≤12Gy irradiation is the main way of lymphocyte death. The up-regulation of Bax and the down-regulation of Bcl-XL after irradiation play an important role in the apoptosis and immune regulation of lymphocytes induced by acute high-dose irradiation.