HLA-G参与骨髓间充质干细胞的抑制作用机制探讨

目的：探讨人骨髓间充质干细胞（MSC）在活体肾移植供受者间的混合淋巴细胞培养（MLR）中的作用机制,证明人白细胞抗原（HLA）-Ⅰ类分子HLA-G参与了MSC的免疫调节作用。方法：从人骨髓中分离培养MSC,采用形态学观察及流式细胞术分析鉴定后,加入活体肾移植供受者间的MLR,观察MSC的HLA-G表达及对T细胞增殖的影响,淋巴细胞增殖实验采用MTT法。结果：MSC细胞表面和胞浆内均表达HLA-G,流式细胞术分析细胞表面HLA-G平均表达率为37.3%,胞浆内HLA-G平均表达率为65.1%,ELISA法检测细胞培养上清中可溶性HLA-G含量为18.9ng/mL。将MSC和培养上清液加入活体肾移植供受者间的MLR体系中,均使得T细胞抑制率增高;而加入HLA-G特异性抗体,MSC的抑制率降低。结论：MSC表面和胞浆内均有HLA-G表达,在其培养上清中检测到由MSC分泌的可溶性HLA-G5;MSC表达和分泌的HLA-G是其发挥抑制功能的关键因素之一。为MSC在预防器官移植术后排斥反应的临床应用提供了理论依据。

Human Leukocyte Antigen-G Secreted by Human Mesenchymal Stem Cells is Required to Suppress T Lymphocyte

Objective： To study the effects and mechanisms of human bone marrow mesenchymal stem cells （MSC） in mixed lymphocyte reaction （MLR）, and to provide evidence of the nonclassic human leukocyte antigen （HLA） class I molecule HLA-G is responsible for the immunology inhibite properties of MSC. Methods： MSC were isolated from adult bone marrow by their capacities to adhere on culture flasks and to proliferate extensively. Depending on the culture con- ditions, MSC were able to either retain their differentiation potential or to differentiate into osteoblasts, HLA-G expression and T cell proliferation by flow cytometry analysis. Soluble HLA-G（sHLA-G） levels in the MSC supernatants by ELISA. MTF assay was used to examine the proliferation of lymphocyte. Results： The study showed that HLA-G expressed in the surface and cytoplasm of MSC, the average rate of HLA-G expression was 37.3% on MSC surface, that was 65.1% in cy- toplasm, sHLA-G levels in cell culture supernatant was 18.9 ng/mL. MSC and the culture supernatant were added in the MLR between the living kidney transplant donors and recipients. The results showed that T-cell inhibition rate was in- creased obviously. And T-cell inhibition rate was decreased meanwhile the HLA-G antibodies co-culture in the group. Conclusion： Data shows the expression of HLA-G in the surface and cytoplasm of MSC, as well as in the supernatants from MSC. Also our results provide evidence that HLA-G5 secreted by MSC is critical to the suppressive functions of MSC. It should contribute to improving clinical therapeutic trials that use MSC to prevent rejection.