The Migration of Peripheral Macrophages to TNCs and Their Role in Antigen Presentation

项目摘要：外周巨噬细胞向胸腺滋养细胞的迁移及其在抗原呈递中的作用。T细胞的最终功能是将病毒感染的细胞从体内清除。为了完成这一任务，T细胞必须能够区分作为身体一部分的细胞，称为自身细胞，以及对身体来说是外来的代理人。在胸腺发育过程中，自身抗原被呈递给发育中的T细胞。T细胞通过其抗原受体（TcR）具有识别抗原呈递（APC）胸腺细胞表面抗原的能力。当自身抗原被呈递给发育中的T细胞时，其TcR与APC表面上的这种蛋白质紧密结合，并且T细胞通过称为凋亡的过程被诱导死亡。这是有道理的，因为如果T细胞被允许成熟并在造血干细胞中释放，它会识别抗原并杀死它所附着的正常B细胞。成熟的T细胞能够确定哪些自身细胞被病毒感染，哪些自身细胞在细胞表面产生外源蛋白。当人们意识到病毒生活并隐藏在它们感染的细胞内时，这是最重要的。Guyden实验室已经从一种APC中开发出了细胞系，这些APC在这一过程中发挥作用，被称为胸腺护士细胞（TNC）。这些细胞对身体来说是独特的，因为它们在抗原呈递过程中实际上将发育中的胸腺细胞吸收到它们的细胞质中。一个尚未回答的主要问题是，当大多数自身抗原位于胸腺外时，所有大量的自身抗原是如何到达胸腺进行抗原呈递的？初步结果表明，其他抗原呈递细胞如巨噬细胞和树突状细胞存在于该TNC复合物中，沿着发育中的胸腺细胞。此外，被染色并返回小鼠肠道的巨噬细胞可以迁移到胸腺并进入TNCs。有人提出，巨噬细胞和树突状细胞，其主要功能是从身体中去除死亡和凋亡细胞，有能力提出自身抗原产生死亡细胞的TNC复合物内的发展T细胞。 将使用具有仅具有一个TcR的T细胞的遗传操作动物进行研究。将跟踪转移到这些动物肠道中的巨噬细胞或树突状细胞的迁移，并将统计学地确定它们诱导足够大数量的发育中的T细胞凋亡的能力。还开发了一种针对TNCs的抗体，并将用于治疗正常小鼠，这将导致其TNCs的消除。将分析这些治疗动物中成熟的T细胞群。如果TNCs在抗原呈递过程中发挥作用，并且自身抗原在它们不存在时不能被呈递，则将检测到具有攻击自身细胞的能力或具有自身免疫原性的成熟T细胞。更广泛的影响：少数民族学生将接受培训，并将参与这一项目。该项目的资金将用于培训7名博士生。在NSF的资助下，38名少数民族本科生参加了实验室的研究，并获得了博士或医学博士学位或继续学习。目前，有：1名博士，2名硕士，3名本科生。

Project Abstract: The migration of peripheral macrophages to thymic nurse cells and their role in antigen presentation.T cells ultimately function to remove virally infected cells from the body. In order for them to accomplish this task, T cells have to be able to distinguish cells that are a part of the body, called self-cells, from agents that are foreign to the body. During development in the thymus, self antigens are presented to developing T cells. The T cells through their antigen receptor (TcR) have the ability to recognize antigens on the surfaces of the antigen presenting (APC) thymic cells. When a self-antigen is presented to developing T cells, its TcR binds tightly to this protein on the surface of an APC and that T cell is induced to die through a process called apoptosis. This makes sense because if the T cell was allowed to mature and released in the blood stem, it would recognize that antigen and kill the normal B cell to which it was attached. Mature T cells are able to determine which self-cells are infected with viruses and which produce foreign proteins on the cell surface. This is most important when one realizes that viruses live and hide inside of the cells that they infect. The Guyden lab has developed cell lines from one of the APCs that function during this process and are called thymic nurse cells (TNCs). These cells are unique to the body because they actually take up developing thymocytes into their cytoplasm during antigen presentation. A major question yet to be answered is, how does all of the large number of self antigens get to the thymus for antigen presentation, when most self antigens reside outside of the thymus? Preliminary results show that other antigen presenting cells like macrophages and dendritic cells exist within this TNC complex along with developing thymocytes. Further, the macrophages that are stained and returned to the gut of a mouse can migrate to the thymus and into TNCs. It is proposed that macrophages and dendritic cells, which have a primary function of removing dead and apoptotic cells from the body, have the ability to present self antigens resulting from dead cells to developing T cells within the TNC complex. Studies using genetically manipulated animals that have T cells with only one TcR will be carried out. Migration of macrophages or dendritic cells transferred into the gut of these animals will be followed and their ability to induce apoptosis in developing T cells in large enough numbers will be determined statistically. An antibody to TNCs has also been developed and will be used to treat normal mice, which will result in the elimination of their TNCs. The population of T cells that mature from these treated animals will be analyzed. If TNCs function during antigen presentation and self-antigen cannot be presented in their absence, mature T cell that have the ability to attack self cells or are auto-immunogenic will be detected. Broader Impact: Minority students will be trained and will be involved in this project. Funds coming from this project will allow the training of seven PhD students. Over the years of NSF funding, 38 minority undergraduate students have participated in research in the laboratory and have since obtained their PhD or MD degrees or are continuing students. Currently, there are: 1 PhD, 2 Masters, and 3 undergraduate students.