摘要目的:探讨CD8 ＋T细胞在抵抗致死型约氏疟原虫17XL( Plasmodium yoelii 17XL, Py 17XL)感染中的作用。 方法:对BALB/c和C57BL/6小鼠腹腔接种 Py 17XL感染红细胞(1×10 6个/0.1 ml)，建立疟原虫感染模型。动态监测小鼠红细胞感染率、生存率。流式细胞术检测CD8 ＋T细胞亚群效应T细胞(T EFF)和记忆T细胞(T CM)数量，检测IFN-γ和颗粒酶B(granzyme B，GB)表达水平，及CD8 ＋T细胞表面CXCR3、CXCR6和CX3CR1表达水平。对 Py 17XL感染C57BL/6小鼠进行FTY720阻断试验，分析CD8 ＋T细胞迁移对 Py 17XL感染的影响。 结果:BALB/c小鼠红细胞感染率在感染后5 d持续上升，8 d达峰值[(79.57±3.82)%]，且明显高于C57BL/6小鼠( P<0.000 1)，感染后9 d小鼠全部死亡。C57BL/6小鼠红细胞感染率在14 d达峰值[(48.19±3.19)%]后逐渐降至0(26 d)，两组生存率差异有统计学意义( P<0.000 1)。流式结果显示，与BALB/c小鼠相比，C57BL/6小鼠脾脏和肝脏CD8 ＋T细胞绝对值数量显著增加( P<0.05)，脾脏和淋巴结CD8 ＋T EFF和CD8 ＋T CM细胞数量显著升高( P<0.05)。与BALB/c小鼠相比，C57BL/6小鼠脾脏和肝脏CD8 ＋T细胞表达GB、IFN-γ及趋化因子水平显著升高( P<0.05)。FTY720阻断试验显示，实验组小鼠生存率显著性下降( P<0.05)，肝脏和脾脏CD8 ＋T细胞绝对数明显下降( P<0.05)；且CD8 ＋CXCR3 ＋T细胞数量显著下调( P<0.05)。 结论:CD8 ＋T细胞通过T EFF和T CM亚群以分泌GB和IFN-γ方式介导抵抗 Py 17XL感染。趋化因子受体CXCR3在介导CD8 ＋T细胞向脾脏和肝脏趋化中发挥重要作用。

abstractsObjective:To investigate the role of CD8 + T cells in lethal Plasmodium yoelii 17XL ( Py 17XL) infection. Methods:BALB/c mice and C57BL/6 mice were infected with Py 17XL-infected red blood cells (1×10 6 cells/0.1 ml) through intraperitoneal injection to establish the mouse models of Py 17XL infection. Parasitemia (the percentage of erythrocytes infected with Py 17XL) and the survival rates of the mice was observed dynamically. Flow cytometry was used to detect the number of effector T cells (T EFF) and central memory T cells (T CM) of CD8 + T cell subpopulations, the expression of IFN-γ and granzyme B (GB) levels, and the expression of surface chemokine receptors CXCR3, CXCR6 and CX3CR1. FTY720 blocking experiment was conducted on Py 17XL-infected C57BL/6 mice to analyze the impact of CD8 + T cell migration on Py 17XL infection. Results:The parasitemia of BALB/c mice increased rapidly 5 d after infection and reached the peak on 8 d [(79.57±3.82)%]. Besides, the parasitemia was higher in BALB/c mice than in C57BL/6 mice 5-8 d after infection ( P<0.000 1). All BALB/c mice died on 9 d. The parasitemia of C57BL/6 mice reached the peak on 14 d [(48.19±3.19)%] and then decreased to 0 on 26 d. There was statistically significant difference in the survival rate between the two groups ( P<0.000 1). Flow cytometry results showed that compared with the BALB/c mice, the absolute number of CD8 + T cells in spleen and liver tissues and the number of CD8 + T EFF and CD8 + T CM cells in spleen and lymph nodes of C57BL/6 mice increased significantly ( P<0.05). Compared with the BALB/c mice, the levels of GB, IFN-γ and chemokines expressed by CD8 + T cells in spleen and liver tissues of C57BL/6 mice increased significantly ( P<0.05). The FTY720 blocking experiment showed that the survival rate, the absolute number of CD8 + T cells in liver and spleen, and the number of CD8 + CXCR3 + T cells decreased significantly in the experimental group ( P<0.05). Conclusions:CD8 + T EFF and CD8 + T CM cells contribute to resistance against Py 17XL infection by secreting GB and IFN-γ. The chemokine receptor CXCR3 plays an important role in mediating the chemotaxis of CD8 + T cells to spleen and liver.