EFFECTS OF FAS LIGAND ON TISSUE GRAFT REJECTION

Fas/Fas-配体系统是一种重要的受体-配体系统， 调节免疫系统中的细胞死亡 功能性Fas的表达 活化T淋巴细胞上的配体诱导表达 fas，从而限制抗原特异性T和B细胞的增殖。 在 Fas配体相反突变为无功能形式导致 免疫缺陷综合征 淋巴细胞的积累。 最近，据观察， Fas配体对组织移植物的保护作用， 推测是通过诱导同种异体反应性淋巴细胞群的死亡。 这 该项目探讨了诱导组织耐受性的可行性， 通过工程化表达Fas配体的同种异体和异种移植物 用于移植的组织。 在项目的第一阶段， 和鼠Fas配体被靶向于专职抗原 通过克隆到一个细胞中，可以将抗原提呈细胞（APC）如朗格汉斯细胞（Langerhans cell）克隆到细胞中。 含有MHC II类Ealpha启动子的表达载体，和 用该构建体构建转基因小鼠。 因此，专业 所有组织中的APC都应表达Fas配体， 将器官如皮肤移植到同种异体或异种动物上， 测试这些器官存活和诱导的能力 宽容 我们将利用小鼠，其中绝大多数 T细胞表达同种异体抗原的独特受体，以评估其作用 Fas配体在同种异体抗原表达组织上的表达。 控制 将由功能上 惰性或载体本身。 该项目的第二部分探讨了 诱导对组织同种异体移植物或异种移植物耐受的可行性， 通过基因直接转染Fas配体基因的组织， 枪 我们已经将人或鼠Fas配体基因克隆到一个 哺乳动物表达载体PCI已用于基因枪 诱导对病毒抗原的免疫的方案。 在该协议中， 来自供体动物的皮肤片段将用fas配体DNA“射击” 并移植到同种异体动物上以评估对移植物的影响 排斥反应

The fas/fas-ligand system is an important receptor-ligand system that regulates cell death in the immune system. Expression of functional fas ligand on activated T lymphocytes induces death of lymphocytes expressing fas and thus limits proliferation of antigen specific T and B cells. In contrast mutation of fas ligand to a nonfunctional form leads to a syndrome of lymphoproliferation and immunodeficiency due to the accumulation of lymphocytes. Recently, it was observed that expression of fas ligand on tissue transplants conferred protection from rejection, presumably by inducing death of alloreactive lymphoid populations. This project explores the feasibility of inducing tolerance to tissue allografts and xenografts by engineered expression of fas ligand on tissues for transplantation. In the first phase of the project, human and murine fas ligand are being targeted to professional antigen presenting cells (APC) such as Langerhans cells by cloning into an expression vector containing the MHC class II Ealpha promoter and constructing transgenic mice with this construct. Thus, professional APCs in all tissues should express fas ligand and transplantation of organs such as skin onto allogeneic or xenongeneic animals will be performed to test the ability of such organs to survive and induce tolerance. We will take advantage of mice in whom the vast majority of T cells express a unique receptor for alloantigen to assess the effect of expression of fas ligand on alloantigen expressing tissue. Controls will consist of a mutated fas ligand construct which is functionally inert or the vector alone. The second part of the project explores the feasibility of inducing tolerance to tissue allografts or xenografts by directly inoculating the tissue with the gene for fas ligand via gene gun. We have cloned the gene for human or for murine fas ligand into a mammalian expression vector, PCI, which has been used in gene gun protocols to induce immunity to viral antigens. In this protocol, a segment of skin from a donor animal will be "shot" with fas ligand DNA and transplanted onto allogeneic animals to assess for effects on graft rejection.