Abstract: Objective　To investigate the dynamics changes of the myeloid?derived suppressor cells (MDSCs) and regulatory T (Treg) cells in mice infected with Echinococcus granulosus and explore the possible biological significance. Methods　Thirty female BALB/c mice of 6 weeks old were randomly divided into the infection and control groups, of 15 mice in each group. Mice in the infection group were intraperitoneally injected with 2 000 E. granulosus protoscoleces, while those in the control group were injected with the same volume of physiological saline. Mouse liver white blood cells were harvested 3 (early stage), 6 (medium stage) and 12 months (late stage) post?infection, and the proportions of MDSCs, their subpopulations (M?MDSCs and PMN?MDSCs) and Treg cells were assessed by flow cytometry. Results　The proportions of MDSCs were (1.61 ± 0.36)%, (5.68 ± 0.69)% and (16.18 ± 0.69)% in mouse liver white blood cells in the infection group 3, 6 and 12 months post?infection with E. granulosus, and (2.19 ± 0.42)%, (0.99 ± 0.07) % and (4.18 ± 0.84)% in the control group, and there were significant differences in the proportion of the MDSCs in mouse liver white blood cells between the infection and control groups 6 and 12 months post?infection (P < 0.01). The proportions of M?MDSCs were (0.69 ± 0.27)%, (5.30 ± 0.72)% and (10.75 ± 0.29)% in mouse liver white blood cells in the infection group 3, 6 and 12 months post?infection, and (0.42 ± 0.24)%, (0.69 ± 0.02)% and (2.12 ± 0.13)% in the control group, and there were significant differences in the proportion of the M?MDSCs in the mouse liver white blood cells between the infection and control groups 6 and 12 months post?infection (P < 0.01). The proportions of PMN?MDSCs were (0.93 ± 0.23)%, (0.32 ± 0.02)% and (5.14 ± 1.03)% in mouse liver white blood cells in the infection group 3, 6 and 12 months post?infection, and (1.77 ± 0.26)%, (0.28 ± 0.05)% and (1.99 ± 0.90)% in the control group, and there were significant differences in the proportion of PMN?MDSCs in mouse liver white blood cells between the infection and control groups 3 and 12 months post?infection (P < 0.05). The proportions of Treg cells were (3.35 ± 0.14)%, (6.24 ± 0.38)% and (3.41 ± 0.07)% in mouse liver white blood cells in the infection group 3, 6 and 12 months post?infection, and (3.48 ± 0.46)%, (3.65 ± 0.45)% and (3.12 ± 0.12)% in the control group, and there were significant differences in the proportion of Treg cells in mouse liver white blood cells between the infection and control groups 6 and 12 months post?infection (P < 0.01). Conclusions　The percentages of both MDSCs and Treg cells increase in mouse liver white blood cells 6 and 12 months post?infection with E. granulosus, and a more remarkable increase is seen in the percentage of MDSCs, which is mainly found in M?MDSCs. These findings suggest that M?MDSCs may play a major immunosuppressive role in the medium and late stages of E. granulosus infection in mice.

Key words: Echinococcus granulosus, Protoscoleces, Myeloid?derived suppressor cell, Regulatory T cell

摘要： 目的　分析细粒棘球蚴感染小鼠肝脏髓源抑制性细胞（MDSCs）和调节性T（Treg）细胞比例动态变化，探讨其可能的生物学意义。方法　将30只6 周龄雌性BALB/c 小鼠随机分为感染组和对照组，每组15只。感染组每只小鼠腹腔注射细粒棘球绦虫原头节约2 000个，对照组注射等体积生理盐水。感染后3、6、12个月（感染早、中、晚期）收集小鼠肝脏白细胞，采用流式细胞术检测其中MDSCs 及其亚型M?MDSCs、PMN?MDSCs 与Treg细胞比例。结果　感染组小鼠感染后3、6、12个月肝脏白细胞中MDSCs 比例分别为（1.61 ± 0.36）%、（5.68 ± 0.69）%和（16.18 ± 0.69）%，对照组分别为（2.19 ± 0.42）%、（0.99 ± 0.07）%和（4.18 ± 0.84）%，感染后6个月和12个月两组差异均有统计学意义（P均 < 0.01）；感染组小鼠感染3、6、12个月后肝脏白细胞中M?MDSCs 比例分别为（0.69 ± 0.27）%、（5.30 ± 0.72）%和（10.75 ± 0.29）%，对照组分别为（0.42 ± 0.24）%、（0.69 ± 0.02）%和（2.12 ± 0.13）%，感染后6个月和12个月两组差异均有统计学意义（P 均< 0.01）；感染组小鼠感染后3、6、12个月肝脏白细胞中PMN?MDSCs 比例分别为（0.93 ± 0.23）%、（0.32 ± 0.02）%和（5.14 ± 1.03）%，对照组分别为（1.77 ± 0.26）%、（0.28 ± 0.05）%和（1.99 ± 0.90）%，感染后3个月和12个月两组差异均有统计学意义（P均 < 0.05）。感染组小鼠感染后3、6、12个月肝脏白细胞中Treg细胞比例分别为（3.35 ± 0.14）%、（6.24 ± 0.38）%和（3.41 ± 0.07）%，对照组分别为（3.48 ± 0.46）%、（3.65 ± 0.45）%和（3.12 ± 0.12）%，感染后6个月和12个月两组差异均有统计学意义（P均＜0.01）。结论　小鼠感染细粒棘球蚴6个月和12个月后，其肝脏白细胞中MDSCs与Treg细胞比例增加，前者比例变化更加明显，以M?MDSCs为主；以上提示M?MDSCs可能在小鼠感染细粒棘球蚴中后期发挥主要免疫抑制作用。

关键词: 细粒棘球绦虫, 原头节, 髓源抑制性细胞, 调节性Ｔ细胞