INTRATHYMIC TRANSPLANTATION TOLERANCE BY MHC PEPTIDES

器官移植是终末期器官衰竭的首选治疗方法。 移植研究的主要目标是诱导对 主要组织相容性复合体(MHC)抗原。胸腺扮演着 在自我容忍发展中的主要作用，但它在后天的作用 对同种异体抗原的耐受性尚不清楚。几名调查人员最近 研究表明，将供体细胞注入成年动物的胸腺内可以 导致对组织和器官长期特定的无反应状态 异体移植。MHC基因序列数据的可用性已经使 合成多态多肽并将其用于研究是可能的 异种识别的机制。胸腺内注射多形核苷 MHC别肽重现与同种异体相同的效果 细胞，这表明胸腺细胞识别经过处理的MHC分子。这个 这项建议的主要重点是利用合成的MHC多肽来研究 大鼠获得性胸腺内耐受的机制 带血管的同种异体器官移植。具体来说，计划将是：1. 探讨MHC别肽的胸腺识别机制。这 将通过研究哪些胸腺抗原提呈细胞， 骨髓来源的巨噬细胞/树突状细胞或上皮细胞，结合 并将MHC别肽呈递给T细胞。方法将包括绑定 生物素化MHC多肽的研究，测定对 处理，并用特定的抗I类和II类MHC进行阻断 单克隆抗体。T细胞对特定MHC表位的反应 在用这些多肽和同种异体移植物免疫后，将 要下定决心。2.研究胸腺调节细胞的作用。这个 将采用大鼠肾和心脏移植模型。.的存在 将通过在以下位置进行胸腺切除术来研究调节机制 移植后不同的时间间隔，进行收养 移植实验，研究移植物浸润性细胞和细胞因子 通过免疫组织学检测。3.研究胸腺对MHC的识别 多肽可以对抗或删除激活的T细胞克隆。这将涉及到 注射诱导对特定MHC表位的免疫无应答 单个MHC多肽进入胸腺，并用于体外增殖 和前驱频率分析，以研究功能特征 来自耐受动物的T细胞。无能的研究将通过测试 细胞因子逆转T细胞无反应性。克隆删除将是 通过分析T细胞受体Vbeta谱系进行研究。从长远来看 目标是开发新的方法来研究 移植无反应，包括新的诱导策略 特异性移植耐受。

Organ transplantation is the therapy of choice for end stage organ failure. The major goal in transplantation research is the induction of tolerance to major histocompatibility complex (MHC) antigens. The thymus plays the major role in development of self tolerance, but its role in acquired tolerance to alloantigen is unknown. Several investigators have recently shown that intrathymic injection of donor cells into adult animals can induce a state of long term specific unresponsiveness to tissue and organ allografts. The availability of sequence data for the MHC genes has made it possible to synthesize polymorphic peptides and utilize them to study the mechanisms of allo-recognition. Intrathymic injection of polymorphic MHC allopeptides reproduces the same effects observed with allogeneic cells, suggesting that thymocytes recognize processed MHC molecules. The main focus of this proposal is to use synthetic MHC peptides to study the mechanisms of acquired intrathymic tolerance in the rat model of vascularized organ allografts. Specifically, the plan will be to: 1. Investigate the mechanisms of thymic recognition of MHC allopeptides. This will be accomplished by studying which thymic antigen-presenting cells, bone marrow-derived macrophages/dendritic cells or epithelial cells, bind and present MHC allopeptides to T cells. Methods will include binding studies of biotinylated MHC peptides, determining the requirement for processing, and blocking with specific anti-class I and class II MHC monoclonal antibodies. The response of T cells to specific MHC epitopes after priming by immunization with the peptides, and by an allograft, will be determined. 2. Investigate the role of thymic regulatory cells. The rat renal and cardiac transplant model will be used. The presence of regulatory mechanisms will be investigated by performing thymectomies at different time intervals after transplantation, performing adoptive transfer experiments, and studying graft infiltrating cells and cytokines by immunohistology. 3. Investigate whether thymic recognition of MHC peptides anergizes or deletes activated T cell clones. This will involve induction of immune unresponsiveness to specific MHC epitopes by injecting individual MHC peptides into the thymus, and using in vitro proliferation and precursor frequency assays to study the functional characteristics of T cells from tolerized animals. Anergy will be studied by testing for reversal of T cell unresponsiveness by cytokines. Clonal deletion will be investigated by analyzing T cell receptor Vbeta repertoire. The long term objectives are to develop novel approaches to study the mechanisms of transplantation unresponsiveness, including new strategies to induce specific transplantation tolerance.