Donor Cell Facilitation of Tolerance

描述(由申请人提供)：该研究计划的长期目标是诱导对同种异体器官移植的免疫耐受，这样就不需要免疫抑制药物来维持永久的移植物接受。该项目之前的研究表明，在接受全淋巴照射(TLI)和抗胸腺细胞血清(ATS)条件下的野生型MHC不相合小鼠中，使用心脏和骨髓联合移植可以实现对同种异体心脏移植的耐受。宿主成为稳定的混合嵌合体，没有发生移植物抗宿主病(GVHD)。GVHD的耐受诱导和预防依赖于宿主调节性自然杀伤(NK)T细胞，在TLI和ATS处理后，NK细胞成为主要的残留T细胞亚群。我们最近的研究表明，耐受性和GVHD的预防也依赖于供体Treg细胞和宿主Treg细胞的发展，这些细胞不是NK T细胞。解释这一结果的一个假设是，宿主NK T细胞与宿主和供体APC相互作用，然后增强/激活非NK Treg细胞，为耐受诱导提供同种异体抗原特异性。而NK T细胞的调节活性依赖于IL-4，而非NK Treg细胞的调节活性依赖于IL-4和IL-10。这一假设将通过将来自野生型、Treg缺陷和细胞因子缺陷(即IL-4“‘、IL-10”’)宿主和供体类型小鼠的纯化的NK T细胞和非NK Treg细胞重新添加到适当的TLI/ATS条件宿主来检验。有条件的宿主将接受MHC不匹配的联合器官和骨髓移植，并将监测移植接受度和移植物抗宿主病。我们最近的研究表明，野生型小鼠的NK T细胞对TLI/ATS诱导的细胞凋亡的抵抗力远高于常规T细胞。然而，在p53“‘”小鼠和转Bcl2基因的小鼠中，这种差异耐药性消失了。我们将确定后一种基因改变的小鼠是否也丧失了诱导耐受和预防GVHD的能力。

DESCRIPTION (provided by applicant): The long-term objective of the research program is to induce immune tolerance to allogeneic organ transplants such that immunosuppressive drugs are not required to maintain permanent graft acceptance. Previous studies in the program have shown that tolerance to heart allografts can be achieved using combined heart and bone marrow transplantation in wild-type MHC-mismatched murine hosts that have been conditioned with total lymphoid irradiation (TLI) and anti-thymocyte serum (ATS). The hosts become stable mixed chimeras without the development of graft versus host disease (GVHD). Tolerance induction and prevention of GVHD is dependent on host regulatory natural killer (NK) T cells that become the predominant residual T cell subset after TLI and ATS conditioning. Our recent studies show that tolerance and GVHD prevention is also dependent on the development of donor Treg cells and host Treg cells that are not NK T cells. A hypothesis that explains the results is that host NK T cells interact with host and donor APC's, and then augment/activate the non-NK Treg cells that provide alloantigen specificity for tolerance induction. Whereas the regulatory activity of the NK T cells is IL-4 dependent, that of the non-NK Treg cells is IL-4 and IL-10 dependent. The hypothesis will be tested by adding back purified NK T cells and non-NK Treg cells from wild-type, Treg deficient, and cytokine deficient (i.e. IL-4"'", IL-10"'") host and donor type mice to appropriate TLI/ATS conditioned hosts. The conditioned hosts will receive combined MHC-mismatched organ and bone marrow transplants, and graft acceptance and GVHD will be monitored. The phenotype and cytokine dependence of the non-NK Treg cells will be determined as well as the dependence of NK T cell activation on interaction with APC's. Our recent studies show that the NK T cells in wild type mice are far more resistant to apoptosis induced by TLI/ATS conditioning than conventional T cells. However, the differential resistance is lost in p53"'" mice and in Bcl-2 transgenic mice. We will determine whether the ability to induce tolerance and prevent GVHD is also lost in the latter genetically altered mice.