免疫排斥成为异种移植在临床应用中的最大障碍，因此免疫耐受的诱导策略成为移植免疫学研究的热点。1型调节性T细胞（type 1 regulatory T cell，Tr1细胞）作为调节性T细胞（Treg）的一种亚群，能在体内外诱导分化并在维持和诱导免疫耐受中扮演着重要作用。我们前期研究发现体外诱导的异种抗原特异性Treg通过IL-10发挥抑制功能。因此我们推测分泌IL-10的人异种抗原特异性Tr1细胞的回输将成为移植免疫疗法的更有效手段。本项目拟通过体外诱导分化具有异种抗原特异性的人Tr1细胞，研究其生物学特性及作用机制，回输抗原特异性Tr1细胞至人源化小鼠异种胰岛移植动物模型中，观察异种胰岛移植物存活时间，研究抗原特异性Tr1细胞诱导异种胰岛移植物耐受的分子机制，评估抗原特异性Tr1细胞诱导异种移植物耐受的效率。本项目的完成将为临床异种移植免疫耐受的诱导提供理论基础和新的可行性方案。

Xenogeneic rejection mediated by T cell response is one of major barriers to be overcome for clinical application of xenotransplantation, therefore strategies for immune tolerance induction need be developed. Type 1 regulatory T (Tr1) cells, as one subset of CD4+ Treg, can be generated from naive T cells in the presence of interleukin-10 (IL-10), which regulate suppressive capacity through IL-10. A numbers of studies suggested that Tr1 cells play an important role in maintaining and inducing immune tolerance. Our preliminary study found that xenoantigen-specific human Treg expanded in vitro showed enhanced suppressive capacity in the pig-human MLR most likely via an IL-10-mediated pathway. Here we hypothesize that a simple method for in vitro induction and expansion of IL-10-secreting xenoantigen-specific human Tr1 cells would be more efficient in transplantation immunotherapy..In this study, xenoantigen-specific Tr1 cells will be generated by human naive CD4+ T cells stimulated with two subsequent cycles of xenoantigen stimulation with recombinant human IL-10. Treg phenotype and suppressive capacity will be assessed after xenoantigen stimulation and mechanism of their suppression will be studied. Furthermore NOD-SCID IL-2rγ-/- mice will be transplanted by neonatal porcine islet cell clusters (NICC) followed by reconstitution of human peripheral blood mononuclear cells (PBMC) with in vitro expanded xenoantigen-specific human Tr1 cells or polyclonal expanded Tr1 cells. Human leukocyte engraftment, function and survival time of islet xenograft will be confirmed by flow cytometric and histological analyses. The mechanism and the efficiency of inducing islet xenograft transplant tolerance by xenoantigen-specific human Tr1 cells will be studied. This study will provide a theory and a feasible method for immune tolerance induction in clinical xenotransplantation.