共刺激分子B7-H1对小鼠髓源性抑制细胞免疫抑制功能的调节作用

The regulative effect of costimulatory molecules B7-H1 on immunosuppressive function of myeloid-derived suppressor cells

目的探讨髓源性抑制细胞（MDSCs）负性共刺激分子（B7-HI）的表达及在增龄相关免疫抑制功能中的作用。方法健康C57BL／6老年（12月龄）及青年（4～8周龄）小鼠各18只。通过流式细胞分析法测定各组小鼠MDSCs上负性协同刺激因子的表达水平，并分别通过免疫磁珠分选法及小鼠淋巴结研磨方法，选得MDSCs及T细胞。T细胞增殖干预实验分5组进行：T细胞羟基荧光素二醋酸盐琥珀酰亚胺脂（CFSE）未标记组；T细胞CFSE标记组；T细胞标记CFSE＋老年MDSCs组；T细胞标记CFSE＋青年MDSCs组以及T细胞标记CFSE＋老年MDSCs＋B7-H1阻断抗体组，观察B7-HI在MDSCs抑制T细胞增殖过程中的作用。结果与青年组比较，老年组MDSCsB7-H1的表达明显增高（t=3．27，P〈O．05）。老年组MDSCs能明显抑制T细胞的增殖（t=5．42，P〈O．05），而青年组MDSCs对T细胞的干预作用不明显（t=0．64，P〉0．05），老年MDSCs加B7-HI阻断抗体组T细胞增殖被明显逆转，差异有统计学意义（￡=8．28，P〈O．05）。结论表达于MDSCs表面的B7-H1分子可能是增龄相关MDSCs发挥免疫抑制功能的重要调节因子。

Objective To explore the expression of negative costimulatory molecule B7-H1 of myeloid derived suppressor cells（MDSCs） and its roles in age-related immunosuppressive functions. Methods 36 C57BL/6 mice were divided into 2 groups： the elderly group（12-month-oId, n= 18） and the young group（4-8-week-old, n=18）. The expressive level of negative costimulatory molecules of MDSCs in the two groups was measured by flow cytometry（FCM）. Besides, MDSCs were sorted by using MDSC isolation kit and T cells were obtained by grinding lymph nodes. To explore the influence of B7-H1 on the MDSCs immunosuppressive functions, T cell proliferation and intervention assay was conducted using the five following groups： T cells group, T cells ＋ CFSE group [T cells with carboxyfluorescein diaeetate succinimidyl ester （CFSE）, T cells ＋ CFSE eocultured with MDSCs from the young group, T cells ＋ CFSE cocultured with MDSCs from the elderly group, and T cells ＋ CFSE cocultured with MDSCs from elderly group and anti-BT-H1 blocking antibody. The effect of B7-H1 on T cell proliferation in MDSCs were observed. Results The expression level of BT-H1 of the MDSCs was significantly increased in the elderly group as compared with the young group（t= 3.27, P〈0.05）. T cell proliferation assay revealed that T cells were remarkably suppressed by MDSCs in elderly group as compared to the youth group（t=5.42, P%0.05）. The suppression of T cells by MDSCs was dramatically reversed by anti-B7-H1 blocking antibody in elderly group（t= 8.28, P〈0.05）. Conclusions BT-H1, a molecule expressed on the surface of MDSCs, plays a key role in the age-related immunosuppressive function of MDSCs.