母子微嵌合状态介导母子免疫耐受的机制研究

Adoptive immunotherapy has greatly improved the outcomes of hematopoietic malignancy, but large doses of donor's lymphocytes infusion would induce severe graft-versus-host diseases (GVHD). We have known that a small number of maternal blood cells exist in the newborn's blood, and in turn, blood cells derived from the offspring can be detected in the mother's blood long after labor. This phenomenon is referred to as fetal-maternal microchimerism, suggesting the presence of immunological tolerance between mother and her offsprings. Recent experimental evidence demonstrate the association between fetal-maternal microchimerism and acquired immune hyporesponsiveness, which is useful for solid organ transplantation and hematopoietic stem cell transplantation (HSCT). Based on this theory, we had successfully treated some EBV-associated lymphoma with high doses of HLA-haploidentical maternal lymphocytes, none of them had developed severe GVHD, which suggest child-maternal tolerance, but what's the mechanism? How the mother's lymphocyte distribute after transfusion and how the anti-tumor effect works? To answer these questions, we are going to build the fetal-maternal-microchimerism mice model to study the mechanism of child-maternal tolerance.

用转基因或者细胞因子刺激后的淋巴细胞治疗肿瘤是有前景的一项过继免疫治疗途径，瓶颈问题是淋巴细胞的来源。尽管供者淋巴细胞输注在治疗干细胞移植后白血病复发取得了显著效果，但是如果大量输注异体淋巴细胞会造成严重的排斥反应。妊娠时期母亲和胎儿间的双向血流交换，可以在母亲和孩子体内形成母子微嵌合体。我们通过基因分析发现，许多母亲体内长期存活着已经成年的孩子的细胞，推测母子可能存在免疫耐受。据此建立输注大剂量HLA单倍型母亲淋巴细胞的方法，成功治疗了一批迄今尚无有效治疗方法的EB病毒相关淋巴瘤，引起国内外学者的关注。问题是，母子间免疫耐受的机制是什么，输注后母亲淋巴细胞在什么地方"归巢"，如何发挥抗肿瘤作用？本研究拟通过转人HLA-A0201基因的C57BL/6与BALB/c交配小鼠的动物模型，探讨母子微嵌合状态诱导母子免疫耐受的机制，为建立更有效、简便、安全的肿瘤过继细胞免疫治疗策略提供理论依据。

研究背景：过继细胞免疫治疗（adoptive cellular immunotherapy，ACI）在血液系统疾病的临床应用已获得广泛认可，成为肿瘤治疗的新途径，但是输注大量异体淋巴细胞可能发生严重的移植物抗宿主病（GVHD）。妊娠时期母亲和胎儿间的双向血流交换，可以在母亲和孩子体内形成母子微嵌合体并长期存在，由此诱导特异的母子免疫耐受，为造血干细胞移植和过继免疫治疗供者选择提供更恰当的机会。研究方法：建立母子微嵌合小鼠模型，通过过继性淋巴细胞输注明确母子间是否存在特异的免疫耐受，以及供受者淋巴细胞亚群的分布变化。研究结果：母体细胞在子代外周血和脾脏中稳定存活；母子组输注时外周血中供者、受者细胞CD3+细胞无明显变化，而母侄组、父子组、无关组CD3+细胞明显增多；母子组受者Treg细胞明显增高，母侄组、无关组Treg细胞没有增多或明显减少；供者细胞在脾脏中始终保持脾脏分布型。结论：过继性淋巴细胞输注时，母子间存在特异的免疫耐受，为建立更有效、简便、安全的肿瘤过继细胞免疫治疗策略提供理论依据。