去甲基化治疗联合HLA半相合T细胞输注诱导白血病特异性CTL生成的机制

白血病是严重威胁人民健康的重大疾病，免疫逃逸是白血病发生与治疗后复发的重要原因，逆转免疫逃逸，重激活免疫杀伤是治愈白血病的关键。去甲基化药物可通过抑制DNA甲基转移酶,激活多种已沉默基因的表达。我们前期的研究发现去甲基化治疗可诱导恶性细胞共刺激分子CD80的表达，增加其免疫原性，强化体内肿瘤特异性CTL的杀伤。据此设计并注册临床试验（NCT01690507），应用去甲基化药物联合CAG化疗后继HLA半相合T细胞输注治疗老年急性髓系白血病，结果两周期诱导缓解率高于80%。本课题拟对临床试验中留取的标本进行检测，从分子、蛋白与细胞水平验证去甲基化治疗后体内白血病细胞免疫原性增加，确认HLA半相合T细胞输注后白血病特异性CTL生成；并利用特异的小鼠模型，复制临床治疗经过，阐明白血病特异性CTL的来源，明确输注各T细胞亚群的作用，为建立新的治疗模式提供理论依据，为进一步优化治疗策略提供思路。

Leukemia remains a serious threat to the health of the people. Immune escape is the major cause for leukaemia occurrence and recurrence after treatment.The most important method to cure leukemia is to reverse the immune escape, and to reactivate immune killing to leukemia. Demethylating agents can induce reexpression of some silent genes by inhibiting the DNA methyltransferase. Our previous studies demonstrated that demethylating treatment can induce the expression of CD80 in malignant cells, increasing its immunogenicity.As a result, tumor-specific CTL responses were enhanced to kill tumor cells in vivo. In a registered a clinical trial (NCT01690507), demethylating agent combined with CAG followed by HLA haploidentical T cells infusion was given to elderly patients with acute myeloid leukemia.The remission rate after the first two cycle induction is higher than 80%. In this project, samples collected from clinical trial will be tested to validate the augmentation of immunogenicity of leukemic cells after demethylating treatment at molecules, protein and cell levels. The generation of leukemia specific CTL will be confirmed after in fusion of HLA haploidentical T cells infusion. In addition, a special mouse model will be employed to explore the source of leukemia specific CTL and identify the role of each subgroup of infused cells. This study will provide theoretical basis for establishing a new combination therapy pattern, meanwhile, we might find some clues for optimizing treatment strategies.