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

Purpose: 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. Materials and methods: 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 1^st, 3^rd, 7^th, 14^th and 21^st 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. Results: 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 1^st day after exposure, worse on 3^rd day, and were relieved on 7^th day. The intestinal immune injuries were observed on 1^st day, and attenuated on 3^rd day. On 21^st 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 21^st day. Conclusion: 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.