ANTIGEN PRESENTING CELLS AND COSTIMULATORY BLOCKADE FOR TOLERANCE INDUCTION

设计自身免疫性疾病新疗法的最终目标 移植是诱导和维持一种状态， 特异性免疫耐受。 我们采用了一种新颖的方法， 研究在T细胞缺乏的情况下抗原呈递的作用 共刺激在自身免疫反应中的应用 自身免疫性脑脊髓炎（EAE）模型。 系统性 施用与致脑炎性细胞一起离体预孵育的APC 髓鞘碱性蛋白（MBP，p71 - 90）和CTLA 41 g的融合肽， 阻断CD28-B7 T细胞共刺激的蛋白质，保护动物 发展成临床EAE 最近的初步数据显示， 这种方法在同种免疫中的潜在适用性;系统性 注射离体预孵育的应答大鼠APC， 免疫显性MHC同种异体肽和CTLA41g也导致 系统耐受性，如延迟型的显著抑制所示 对别肽的超敏反应。 这个项目的主要目标是 建议是了解系统性的效应机制， 由APC诱导的耐受性，所述APC已被修饰以呈现 抗原，但不向T细胞递送共刺激信号。 我们将 研究离体处理的具有致脑炎的APC的耐受性 肽和CTLA41g在复发小鼠EAE模型中的作用， 其具有临床相关性，因为其类似于患者的过程 多发性硬化症我们将确定哪种骨髓来源于 APC负责诱导耐受并研究 B7 - 1相对于B7 - 2分子的选择性阻断。免疫组织 体外研究将确定免疫应答的类型（Th1/Th2） 在耐受的动物中。 连续转移研究将表明， 可能影响感染型的调节细胞的存在 耐受性是一种可能由Th2细胞介导的现象。的 耐受的效应机制将通过使用MBP来证实 TCR转基因小鼠研究无反应性/缺失或诱导 体内调节性Th2细胞。另一个主要目标是研究 体外处理的APC在全身耐受性中的作用和机制 血管化心脏移植物 我们将定义免疫显性 C57 BL/6（H-2b）受体中的Balb/c（H-2d）MHC肽。 我们将 然后研究离体预孵育的受体APC的耐受性， 与免疫显性MHC同种异体肽和CTLA 41g。 耐受机制将通过体外增殖和 细胞因子研究，通过心脏移植物的免疫组织学分析， 和通过过继转移实验。克隆别肽的能力 来自耐受动物的特异性T细胞将帮助我们确认 Th2细胞的免疫调节功能。 结果 拟议的研究应对发展产生重要影响 诱导抗原特异性耐受的新策略， 自身免疫性疾病和移植。

The ultimate goal in designing new therapies for autoimmune diseases and transplantation is the induction and maintenance of a state of specific immunologic tolerance. We have used a novel approach to study the role of antigen presentation in the absence of T cell costimulation in autoimmune responses using the experimental autoimmune encephalomyelitis (EAE) model in LEW rats. Systemic administration of APCs preincubated ex-vivo with the encephalitogenic peptide of myelin basic protein (MBP, p71-90) and CTLA41g, a fusion protein which blocks CD28-B7 T cell costimulation, protects animals from developing clinical EAE. More recent preliminary data show the potential applicability of such an approach in alloimmunity; systemic injection of responder rat APCs preincubated ex-vivo with an immunodominant MHC allopeptide and CTLA41g also results in systemic tolerance, as indicated by significant inhibition of delayed type hypersensitivity responses to the allopeptide. The major goal of this proposal is to understand the effector mechanisms of systemic tolerance induced by APCs which have been modified to present antigen but to not deliver a costimulatory signal to T cells. We will study the tolerogenicity of ex-vivo treated APCs with encephalitogenic peptide and CTLA41g in the relapsing mouse EAE model, a model which has clinical relevance since it resembles the course of patients with multiple sclerosis. We will define which bone-marrow derived APC is responsible for induction of tolerance and study the role of selective blockade of B7-1 versus B7-2 molecules. Immunohistological and in vitro studies will define the type of immune response (Th1/Th2) in tolerized animals. Adoptive transfer studies will indicate the presence of regulatory cells which may effect an infectious-type tolerance, a phenomenon which may be mediated by Th2 cells. The effector mechanisms of tolerance will be confirmed by using MBP TCR transgenic mice to study anergy/deletion or induction of regulatory Th2 cells in vivo. The other major goal is to study the role and mechanisms of ex-vivo treated APCs in systemic tolerance to vascularized cardiac allograft. We will define the immunodominant Balb/c (H-2d) MHC peptides in C57BL/6 (H-2b) recipients. We will then study the tolerogenicity of recipient APCs preincubated ex-vivo with the immunodominant MHC allopeptides and CTLA41g. Mechanisms of tolerance will be studied by in vitro proliferative and cytokine studies, by immunohistological analysis of cardiac allograft, and by adoptive transfer experiments. The ability to clone allopeptide specific T cells from tolerized animals will help us confirm immunoregulatory function of Th2 cells in vivo. Results of the proposed studies should have important implications for development of novel strategies for induction of antigen-specific tolerance in autoimmune disease and transplantation.