DC细胞在辐射损伤抗原递呈及T细胞活化中的作用

目的 利用体外细胞共培养技术模拟体内肺组织微环境，探索树突状细胞（DC）在辐射损伤细胞的抗原提呈作用。方法 ⁶⁰Co γ射线照射的小鼠肺上皮细胞（MLE-12）与骨髓来源DC和/或脾T淋巴细胞培养48 h，流式细胞术检测DC细胞共刺激分子CD80/86和抗原肽识别复合物MHC Ⅰ/Ⅱ表达水平，T细胞活化标志CD69/28/152表达水平以及CD4⁺和CD8⁺亚群细胞数。结果 ⁶⁰Co γ射线照射的MLE-12细胞凋亡率呈剂量依赖性增高，明显刺激DC细胞CD80/86和MHC II表达，但对T细胞无直接活化作用；6 Gy照射的MLE-12细胞与DC细胞和T淋巴细胞共培养48 h，T细胞CD69和CD28表达增加，CD4⁺和CD8⁺亚群细胞数均明显高于对照组，同时DC细胞出现CD86和MHCI特异性高表达。结论 辐射损伤细胞可刺激DC细胞抗原提呈功能，并对T细胞进行活化。

Antigen presentation and T cell activation by dendritic cells in radiation damage

Objective To explore dendritic cells (DCs)-mediated antigen presentation for radiation-injured cells by using the in vitro cell co-culture technology to simulate the in vivo microenvironment of the lung tissue. Methods ⁶⁰Co γ-irradiated mouse lung epithelial cells (MLE-12) were cultured with bone marrow-derived DCs and/or splenic T lymphocytes for 48 hours. Flow cytometry was used to measure the expression levels of costimulatory molecules (CD80/86) and antigenic peptide recognition complexes (the major histocompatibility complex MHC] class Ⅰ/Ⅱ) on DCs and T cell activation markers (CD69/28/152) as well as the numbers of CD4⁺ and CD8⁺ T cells.Results ⁶⁰Co γ irradiation significantly increased the apoptosis rate of MLE-12 cells in a dose-dependent manner, and significantly stimulated the expression of CD80/86 and MHC Ⅱ on DCs, without direct activation of T cells. After γ (6 Gy)-irradiated MLE-12 cells were co-cultured with DCs and T lymphocytes for 48 h, there were significant increases in the expression of CD69 and CD28 on T cells, the numbers of CD4⁺ and CD8⁺ T cells, and the expression of CD86 and MHC I on DCs, as compared with the control groups. Conclusion Radiation-injured cells can stimulate antigen presentation by DCs and activate T cells.