mPEG遮蔽供者淋巴细胞减轻移植物抗宿主病的研究

Study on the attenuation of graft versus host disease by methoxy polyethylene glycol modification of donor lymphocytes

目的 :探讨向SCID小鼠移植甲氧基聚乙二醇 (mPEG)修饰的人脐血单个核细胞时 ,因供体淋巴细胞表面抗原被遮蔽降低了移植物抗宿主病 (GVHD)而不影响其干祖细胞造血功能重建。方法 :(1)用流式细胞仪检测修饰前后人脐血单个核细胞中CD4 + 、CD8+ T细胞及CD4 + /CD8+ T细胞比率的变化。 (2 )观察遮蔽前后 ,人脐血干祖细胞在体外培养形成CFU GM的差异。 (3)将修饰前后的单个核细胞移植到SCID小鼠体内 ,观察GVHD出现的时间和小鼠活存状况。 (4)移植后 7wk左右测定小鼠骨髓中人源CD4 5 + 细胞的含量。结果 :(1)mPEG几乎可完全遮蔽T细胞表面的CD4和CD8抗原。 (2 )修饰前、后的干祖细胞 ,体外培养形成CFU GM的数量没有明显差异。 (3)将修饰的人脐血单个核细胞移植到小鼠体内 ,GVHD出现的时间晚于未修饰组 ,提高了小鼠的活存率。 (4)移植后 4 7d ,活杀小鼠的骨髓细胞中 ,可检测到人的CD4 5 + 细胞。结论 :用mPEG遮蔽供体T细胞表面的CD4、CD8抗原 ,最终减轻了宿主对移植物的免疫应答 ,而干祖细胞增殖、分化的功能未受到明显影响。

AIM: To find out why mPEG modification of donor’s lymphocytes can attenuate the occurrence of graft versus host disease(GVHD), but not affect the hemopoietic reconstitution of stem/progenitor cells after transplanting the mPEG modified mononuclear cells from human cord blood into the SCID mice. METHODS: The followings were observed: (1) Changes of CD4 + and CD8 + T cells and the ratio of CD4 +/CD8 + T cells were examined by flow cytometry before and after mononuclear cells from human cord blood were modified with mPEG. (2) The difference in forming the CFU GM in vitro between the mPEG modified stem/progenitor cell group and non modified cell group was observed. (3) The time of appearance of GVHD and the survival of the SCID mice were observed after the pre and post modification mononuclear cells were transplanted. (4) The number of humanized CD45 + cells in the mouse’s bone marrow was detected about 7 weeks after transplantation. RESULTS: (1) mPEG nearly completely covered up the CD4 and CD8 antigens on T cells, while the number of CFU GM did not show any obvious change between the modified and non modified cell groups. (2) GVHD appeared later in the modified mononuclear cell group than in the non modified group, and the survival rate was elevated in the modified group than in the non modified group. (3) Humanized CD45 cells were found in mouse’s bone marrow at the 47th day after transplantation of both mPEG modified and non modified mononuclear cells. CONCLUSION: After CD4 and CD8 antigens were covered up with mPEG, the graft’s immune response against host was weakened, but the proliferation and differentiation of transplanted hemopoietic stem/progenitor cells were not affected.