Donor Cell Facilitation of Tolerance

描述（由申请人提供）：研究项目的长期目标是诱导对同种异体器官移植的免疫耐受，因此不需要免疫抑制药物来维持永久性移植物接受。该项目的先前研究表明，在已接受全淋巴照射（TLI）和抗胸腺细胞血清（ATS）处理的野生型MHC不匹配小鼠宿主中，使用心脏和骨髓联合移植可实现心脏同种异体移植耐受。宿主成为稳定的混合嵌合体，而不会发生移植物抗宿主病（GVHD）。GVHD的耐受性诱导和预防依赖于宿主调节性自然杀伤（NK）T细胞，其在TLI和ATS调节后成为主要的残余T细胞亚群。我们最近的研究表明，耐受性和GVHD预防也依赖于供体Treg细胞和非NK T细胞的宿主Treg细胞的发育。解释该结果的假设是宿主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，其为耐受诱导提供同种抗原特异性。而NK T细胞的调节活性是IL-4依赖性的，非NK Treg细胞的调节活性是IL-4和IL-10依赖性的。将通过将来自野生型、Treg缺陷型和细胞因子缺陷型（即IL-4+、IL-10+）宿主和供体型小鼠的纯化的NK T细胞和非NK Treg细胞添加回适当的TLI/ATS条件化宿主中来测试该假设。条件化宿主将接受组合的MHC不匹配的器官和骨髓移植，并监测移植物接受性和GVHD。将确定非NK Treg细胞的表型和细胞因子依赖性以及NK T细胞活化对与APC相互作用的依赖性。我们最近的研究表明，野生型小鼠中的NK T细胞对TLI/ATS调节诱导的细胞凋亡的抗性远高于常规T细胞。然而，在p53+小鼠和Bcl-2转基因小鼠中，差异抗性丧失。我们将确定诱导耐受性和预防GVHD的能力是否也在后一种基因改变的小鼠中丧失。

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.