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目的 探讨低剂量辐射对致癌剂量辐射诱发小鼠胸腺淋巴瘤的影响及其免疫学机理。方法 采用 4次 1 75GyX射线全身照射C57BL/ 6J小鼠诱发胸腺淋巴瘤模型 ,观察不同剂量照后 6个月小鼠胸腺淋巴瘤发生率 ,照后 1个月脾脏NK细胞毒活性、IL 2和γ IFN分泌活性、腹腔巨噬细胞吞噬功能及其TNFα分泌活性以及胸腺细胞分化的变化。结果 每次 1 75Gy照射前 6h或 1 2h接受 2 5mGy或 75mGy全身照射均可降低胸腺淋巴瘤发生率 ,且预先接受 75mGy全身照射的作用效果更为明显 ;每次 1 75Gy照射前 1 2h接受 75mGy照射小鼠 ,上述免疫指标均比单纯1 75Gy照射组增强 ,且多数指标接近假照射组 ;其胸腺CD4- CD8- 和CD4- CD8+ 细胞较单纯 1 75Gy照射组减少、CD4+ CD8+ 细胞增多。结论 低剂量辐射可诱导辐射诱发胸腺淋巴瘤适应性反应 ,对致癌剂量辐射诱发小鼠胸腺淋巴瘤有抑制作用 ,其抑制作用的免疫学机理可能与低剂量辐射的免疫增强效应及诱导的免疫学适应性反应 ,减轻致癌剂量辐射对机体免疫功能的损伤 ,使胸腺淋巴瘤前体细胞在形成胸腺淋巴瘤之前被免疫系统清除有关
Objective To investigate the effect of low dose radiation on tumor-induced radiation-induced thymic lymphoma in mice and its immunological mechanism. Methods The thymic lymphoma model was induced by C57BL/6J mice irradiated with four times 75Gy X-rays. The incidence of thymic lymphoma in mice was observed 6 months after irradiation at different doses. The NK cytotoxicity activity, IL 2 and spleen were measured at 1 month after irradiation. IFN-γ secretion activity, peritoneal macrophage phagocytosis and TNFα secretion activity, and thymocyte differentiation. Results The incidence of thymic lymphoma could be reduced by receiving either 25mGy or 75mGy total body irradiation 6h or 1 2h before irradiation, and the effect of 75mGy total body irradiation in advance was more obvious; 75mGy was accepted before 1 2h of irradiation before 1 75Gy irradiation. Irradiated mice, the above immune parameters were enhanced compared to the radiated 175Gy group alone, and most of the indicators were close to the sham irradiation group; the thymus CD4-CD8- and CD4-CD8+ cells were reduced compared to the 175Gy irradiation group alone, and CD4+CD8+ cells were increased. Conclusion Low-dose radiation can induce adaptive responses to radiation-induced thymic lymphoma and inhibit the oncogenic dose of radiation-induced thymic lymphoma in mice. The immunological mechanism of inhibition may be related to the immunopotentiating effect of low-dose radiation and induced immunology. The adaptive response reduces the damage to the body’s immune function caused by the radiation of carcinogenic doses, so that the thymic lymphoma precursor cells are cleared by the immune system before the formation of thymic lymphoma.