中子及γ射线照射后小鼠肠免疫组织病理特点及淋巴细胞凋亡研究

Pathologic characteristics of gut-associated lymphoid tissues and lymphocyte apoptosis in mouse intestine after neutron-and γ-irradiation

目的 比较研究中子及γ射线照射对肠黏膜免疫组织损伤的病理特点及淋巴细胞凋亡情况。方法 经不同剂量的中子及γ射线照射 35 0只BALB/c小鼠 ,于照后 6h、12h、1～ 5d、7d、14d、2 1d及 2 8d活杀取全肠 ,经光镜、电镜和原位末端标记等技术研究肠黏膜免疫组织的病理变化及淋巴细胞死亡方式。结果 中子照后肠免疫组织的基本病变为淋巴细胞变性、凋亡、坏死及数目减少 ,中子 4 0及 5 5Gy照射后未见明显再生 ,2 5Gy组则见再生修复现象 ,且呈剂量相关性 ;中子2 5Gy照后 6h～ 3d ,黏膜内及下淋巴组织中淋巴细胞逐渐减少 ,核固缩及大量核碎片形成 ,3d时淋巴组织中仅残留间质细胞 ,隐窝细胞见再生。 5d时淋巴组织始见增生 ,至照后 2 1d基本恢复至正常水平。γ射线照射后基本病变与中子类似 ,5 5Gy组见再生恢复 ,而 12 0Gy组未见明显再生。原位末端标记显示各照射组于照射后 6h肠黏膜免疫组织中凋亡的淋巴细胞明显增加 ,尤以中子4 0Gy和γ射线 12 0Gy更为明显。结论 2 5～ 5 5Gy中子及 5 5～ 12 0Gyγ射线照射均可致明显肠壁淋巴组织损伤 ,且在相同剂量下 ,中子对免疫组织损伤重于γ射线 ;免疫组织损伤重 ,且恢复慢 ;4 0Gy以上中子照射多见淋巴细胞坏死 ,而 5 5～ 12 0Gyγ射线则以凋亡为主?

Objective To compare the pathologic characteristics of gut-associated lymphoid tissues and lymphocyte apoptosis in neutron-irradiated mouse small intestines with those in γ-irradiated ones. Methods Altogether 350 BALB/c mice were irradiated with different doses of neutrons or γ-rays,and were sacrificed on 6 h,12 h,15 d,7 d,14 d,21 d and 28 d after irradiation and their total intestines were remored. Then the pathologic changes and death mode of lymphocytes in gut-associated lymphoid tissues were studied comparatively with light microscopy,electron microscopy and in situ terminal labeling method. Results The basic pathologic changes of gut-associated lymphoid tissues after neutron irradiation included degeneration,apoptosis and necrosis of lymphocytes. The number of lymphocytes also decreased. There was no obvious regeneration after 4.0 and 5.5 Gy neutron irradiation,while after 2.5 Gy regeneration and recovery appeared,which were,there fore,dose-dependent. In the 2.5 Gy neutron group,the numbers of lymphocytes of intramucosal and submucous lymphoid tissues decreased,and karyopyknosis and a great quantity of nuclear fragments could also be observed at 6 h3 d after irradiation. However,on the 3rd day regeneration of crypt epithelial cells appeared. On the 5th day hyperplasia of submucous lymphocytic tissues appeared,but recovery to normal level was not achieved till 14 d after irradiation. The basic pathologic changes after γ-irradiation were similar to that of neutron irradiation. Regeneration and recovery appeared in the 5.5 Gy group while no obvious regeneration in the 12.0 Gy group. The results of in situ terminal labeling indicated that at 6 h after irradiation the number of apoptotic cells in gut-associated lymphoid tissues of each group increased obviously,while in 4.0 Gy neutron group and 12.0 Gy γ-ray group it was more abundant. Conclusion Both 2.55.5 Gy neutron and 5.512.0 Gy γ-ray irradiation can induce obvious injuries in gut-associated lymphoid tissues,and the effect of neutron is more severe man that of γ-rays under the same irradiation doses. Injuries of immune tissues are more severe and recovery of them are more slowly in comparation with those of intestinal epithelial tissue. More lymphocytic necrosis can be observed after neutron irradiation above 4.0 Gy, while after 5.512.0 Gy γ-irradiation apoptosis appears to be most serious.;