中文摘要：

目的：检测STAT3在乳腺癌MDSCs中的磷酸化状态及其对MDSCs免疫抑制活性的影响。方法：收集脐血单个核细胞，免疫磁珠的方法分选其中CD33＋细胞，体外与乳腺癌细胞系MDA-MB-231共孵育诱导MDSC生成。Western blot方法分别检测IDO和STATs的表达与磷酸化情况。MDSCs与健康供者外周血T淋巴细胞共孵育，分别加入1-MT和JSI-124来抑制IDO功能和STAT3磷酸化，利用MTT实验和ELISA检测各组T细胞的增殖和细胞因子分泌。结果：Western blot检测发现体外诱导的MDSCs中IDO表达明显增加，同时伴STAT3磷酸化水平升高。加入JSI-124后pSTAT3和IDO表达明显降低。MTT实验中MDSCs明显抑制T细胞增殖，加用IDO特异性抑制剂1-MT或STAT3抑制剂JSI-124后T细胞增殖抑制明显改善（P〈0.05），且1-MT组和JSI-124组之间差异无统计学意义。ELISA结果显示MDSCs显著抑制T细胞分泌IFN-γ，促进TGF-β、IL-10释放（P〈0.05）。而加用1-MT或JSI-124后，IFN-γ分泌水平升高，而TGF-β、IL-10分泌水平降低（P〈0.05），而1-MT组和JSI-124组之间差异无统计学意义。结论：MDSCs中磷酸化STAT3水平升高导致IDO过表达；STAT3的特异性抑制剂JSI-124可以逆转MDSCs对T细胞增殖和Th1类因子分泌的抑制作用。

英文摘要：

Objective：To explore the status of STAT3 phosphorylation in myeloid-derived suppressor cells （MDSCs） of breast cancer and its function in the immunosuppressive effect of MDSCs on proliferation and cytokine secretion of T cells. Methods：CCD33＋cells were isolated from healthy umbilical cord, blood-derived, peripheral blood mononuclear cells and were co-cultured with breast cancer cell line MDA-MB-231 in vitro using Transwell plates to induce MDSCs. The untreated CD33＋cells were used as con-trols. Idoxuridine （IDO） suppressor expression and STAT3 phosphorylation were examined using Western blot assay. The proliferation and cytokine secretion of T cells, which were co-cultured with MDSCs, were determined by methyl thiazol tetrazolium assay and en-zyme-linked immunosorbent assay. 1-MT and JSI-124 were used to investigate the function of IDO and pSTAT3 in MDSC-mediated T cell immunosuppression. Results：The protein levels of IDO and pSTAT3 in MDSCs were significantly upregulated. MDSCs obviously suppressed T-cell proliferation, which was reversed by 1-MT or JSI-124 （P〈0.05）. MDSCs could promote TGF-βand IL-10 secretions, but could also remarkably inhibit IFN-γsecretion （P〈0.05）. After incubation with 1-MT or JSI-124, the increase in TGF-βand IL-10, as well as the decrease in IFN-γ, was significantly reversed. Conclusion：The upregulated pSTAT3 induced the IDO increase in MDSCs. JSI-124 can block MDSC-mediated immunosuppressive effect on T cells in breast cancer.