CD8^+耗竭T细胞在致死型约氏疟原虫感染Balb/c和C57BL/6中的差异表达及意义

The differential expression and its significance of CD8^+exhausted T cells in Balb/c and C57BL/6 mice infected by lethal Plasmodium yoelii

目的探讨致死型约氏疟原虫(Plasmodium yoelii17XL,P.y 17XL)感染Balb/c和C57BL/6小鼠脾脏CD8^+耗竭T细胞的差异表达及意义。方法采用新鲜P.y 17XL感染红细胞(1×10^6)腹腔感染Balb/c和C57BL/6小鼠,动态检测红细胞感染率并观察小鼠生存率。研磨法分离脾脏淋巴细胞。流式细胞术检测CD8^+T细胞效应和耗竭细胞亚群数量和分泌IFN-γ和颗粒酶B(GB)水平。结果P.y 17XL感染后第4~8天,Balb/c组红细胞感染率显著性升高且明显高于C57BL/6组(P<0.001),C57BL/6组生存率明显高于Balb/c组(53.8%vs 0,P<0.001)。感染后第5天流式结果显示,C57BL/6组CD8^+CD44^+CD62L^-T细胞(P<0.01)、CD8^+IFN-γ^+T细胞(P<0.05)和CD8^+GB^+T细胞(P<0.001)含量均显著高于Balb/c组。与C57BL/6组相比,Balb/c组CD8^+PD-1^+Tim-3^+T细胞数量明显升高(P<0.001),且GB荧光强度显著性降低(P<0.05)。结论P.y 17XNL红内期感染诱导产生CD8^+PD-1^+Tim-3^+耗竭T细胞,其IFN-γ和GB分泌水平下调,进而影响原虫血症的控制。

This study was performed to investigate the differential expression and its significance of spleen exhausted CD8^+T cells in Balb/c and C57BL/6 mice infected by lethal Plasmodium yoelii(P.y).Balb/c and C57BL/6 mice were infected intraperitoneally with fresh P.y 17XL-infected RBC(1×10^6).Blood samples were taken from the tail vein to detect parasitemia,and the survival rate of mice was observed.Spleen lymphocytes were isolated and the number and levels of secreting IFN-γand Granzyme B(GB)of exhausted CD8^+T cells were analyzed by flow cytometry.Data showed that at the days 4-8 post infection,the parasitemia increased remarkably and was significantly higher in Balb/c group as compared to C57BL/6 group(P<0.001),and the survival rate of C57BL/6 group was significantly higher than that of Balb/c group as well(53.8%vs 0,P<0.001).Flow cytometry analysis on day 5 post infection showed that the population of CD8^+CD44^+CD62 L^-T cells(P<0.01),CD8^+IFN-γ^+T cells(P<0.05)and CD8^+GB^+T cells(P<0.001)were obviously higher in C57BL/6 group compared to Balb/c group;the frequency of CD8^+PD-1^+Tim-3^+T cells in Balb/c group were higher than those in C57BL/6 group(P<0.001).Furthermore,the granzyme B fluorescence intensity in CD8^+PD-1^+Tim-3^+cells were significantly lower in Balb/c group(P<0.05).In conclusion,CD8^+PD-~1^+Tim-3^+T cells lead to a downregulation of GB and IFN-γ,and thereby affected the level of parasitemia.