The injuries of spleen and intestinal immune system induced by 2-Gy ⁶⁰Co <b>γ</b>-ray whole-body irradiation

The aim of the present study was to investigate the injuries of spleen and intestinal immune system induced by 2 Gy ⁶⁰Co γ ray in mice. A total of 120 Balb/c mice were randomly divided into two groups: blank control (Ctrl) and model (IR). The IR mice were exposed to a single dose of total body irradiation (2 Gy, dose rate: 1 Gy/min) and sacrificed on 1st, 3rd, 7th, 14th and 21st day after irradiation. The indicators including general observations and body weight, the changes in peripheral hemogram, spleen index, histopathology examination and lymphocyte subsets of spleen. As well as the count and subsets of lymphocyte in gut-associated lymphoid tissue. Compared with the Ctrl group, the body weight, spleen index, peripheral blood cell and splenocyte amounts, intraepithelial lymphocytes number decreased significantly after exposure, accompanied by a notable decreased count of lymphocytes in Peyer’s patch and mesenteric lymph nodes. Moreover, ionizing radiation also broke the balance of CD4+/CD8+ and increased the Treg proportion in spleen, which then triggered immune imbalance and immunosuppression. In general, the spleen injuries occurred on 1st day after exposure, worse on 3rd day, and were relieved on 7th day. The intestinal immune injuries were observed on 1st day, and attenuated on 3rd day. On 21st day after exposure, the spleen volume and index have returned to normal, except for the distribution of lymphocyte subpopulations. Furthermore, all indicators of gut-associated lymphoid tissue, except for mesenteric lymph nodes lymphocyte count, had returned to normal levels on 21st day. In conclusion, our data showed the injuries of spleen and intestinal immune system induced by 2 Gy ⁶⁰Co γ ray whole-body irradiation. These findings may provide the bases for further radiation protection in the immunity.

本研究旨在探究2 Gy 钴-60（⁶⁰Co）γ射线对小鼠脾脏与肠道免疫系统造成的损伤。共计120只Balb/c小鼠被随机分为两组：空白对照组（Ctrl）与模型组（IR）。模型组小鼠接受单次全身照射（剂量为2 Gy，剂量率：1 Gy/min），并分别于照射后第1、3、7、14及21天处死取材。检测指标涵盖一般状态观察与体重变化、外周血象变化、脾脏指数测定、组织病理学检查以及脾脏淋巴细胞亚群分析，同时包括肠道相关淋巴组织中淋巴细胞的计数与亚群分布检测。与空白对照组相比，照射后小鼠体重、脾脏指数、外周血细胞及脾细胞数量均显著下降，肠上皮内淋巴细胞数量亦随之减少，派尔集合淋巴结（Peyer’s patch）与肠系膜淋巴结（mesenteric lymph nodes）中的淋巴细胞计数同样显著降低。此外，电离辐射还破坏了脾脏内CD4⁺/CD8⁺的比值平衡，并升高了调节性T细胞（Treg）的占比，进而引发免疫失衡与免疫抑制。整体而言，脾脏损伤于照射后第1天出现，第3天病情加重，至第7天有所缓解；肠道免疫损伤则于照射后第1天被观测到，第3天呈减轻趋势。照射后第21天，小鼠脾脏体积与脾脏指数均恢复至正常水平，仅淋巴细胞亚群分布尚未恢复正常。此外，除肠系膜淋巴结淋巴细胞计数外，肠道相关淋巴组织的各项指标均于第21天恢复至正常水平。综上，本研究数据证实了2 Gy ⁶⁰Co γ射线全身照射可诱发小鼠脾脏与肠道免疫系统损伤。上述研究结果可为后续免疫相关辐射防护研究提供理论依据。