MAINTENANCE OF ORAL TOLERANCE BY CD4+ T CELLS IN VIVO

口服耐受是指对膳食抗原的免疫耐受，是避免肠道内对大量外来抗原产生有害炎症反应的关键机制。饮食抗原也可能是T细胞系统刺激的重要来源，因此可能在塑造外周T细胞的功能表型中发挥作用。口服耐受性和外周耐受性的机制通常知之甚少，主要是因为直到最近还不可能在体内追踪抗原特异性T细胞。几年前，我们的实验室通过开发一种DO11.10 TCR转基因cd4 + T细胞的过继转移系统来解决这个问题。该提案描述了使用该系统的进一步方法进展，现在允许在体内抗原刺激后直接检查单个抗原特异性CD4+ T细胞内的生化活性。使用这些方法，我们想表征体内耐受诱导后发现的T细胞的“无能”状态。然而，我们的初步数据表明，耐受性不能简单地归因于抗原特异性T细胞的功能失活，而是“耐受”环境的功能。主要使用细胞免疫学技术，我的目标是确定构成这种环境的关键成分。在对抗原特异性CD4+细胞的CD25+亚群的研究中，这两个特定目标之间的界限模糊，这些细胞仅在耐受原性抗原暴露后出现，特别是抗原喂养。这些细胞似乎是“无能”和潜在的“抑制性”。我相信在马克·詹金斯博士的指导下为我作为一名完全独立的调查员发展的最后阶段提供了一个理想的环境。该实验室继续处于研究体内抗原特异性CD4+ T细胞反应的前沿技术。额外几年的指导将是有帮助的，因为我对T细胞反应的详细生物化学的兴趣是我过去研究经验的一个相对较新的补充。我相信，要想成为一名全面发展的研究人员，扩大我的训练范围，尝试从分子的角度来看待生物学问题是至关重要的。目前大多数的建议集中在口服耐受作为一种形式的全身免疫耐受。然而，直接检查抗原特异性CD4+ T细胞对肠道内膳食抗原的反应是该建议的重要组成部分。这也将是我今后研究的主要方向。最后，作为一名学术胃肠病学家，我最感兴趣的是应用来自动物研究的概念来理解和治疗人类胃肠道内涉及免疫失调的疾病。

Oral tolerance, a term applied to immunologic tolerance toward dietary antigens, is a critical mechanism for avoiding harmful inflammatory reactions toward numerous foreign antigens in the intestine. Dietary antigens may also be an important source of stimulation for T cells systematically and may therefore play a role in shaping the functional phenotype of peripheral T cells. Mechanisms of oral tolerance, and peripheral tolerance in general are poorly understood primarily because until recently it has been impossible to track antigen-specific T cells in vivo. Several years ago our laboratory has developed one solution to this problem by developing an adoptive transfer system of DO11.10 TCR transgenicCD4+ T cells. This proposal describes further methodological advances in the use of this system that now allow direct examination of biochemical activity within individual antigen-specific CD4+ T cells following antigenic stimulation in vivo. Using these methods we would like to characterize the "anergic" state of T cells found in vivo following tolerance induction. Our preliminary data, however, show that tolerance cannot be simply attributed to functional inactivation of antigen-specific T cells, but is also a function of the "tolerized" environment. Using primarily cellular immunology techniques I aim to identify the critical components of what constitutes this environment. The borders between the two specific aims blur in the study of the CD25+ sub-population of antigen-specific CD4+ cells that arise only following tolerogenic antigen exposure, particularly antigen feeding. These cells appear to be both "anergic" and potentially "suppressive". I believe staying under mentorship of Dr. Marc Jenkins represents an ideal situation for this final stage of my development as a fully independent investigator. This laboratory continues to be at the cutting technical edge of studying antigen-specific CD4+ T cell response in vivo. Additional years of mentorship would be helpful since my interests in detailed biochemistry of T cell responses are a relatively recent addition to my past research experiences. I believe extending my training to include attempts to view biological problems in more molecular terms is critical to becoming a well-rounded researcher. Most of the current proposal centers on oral tolerance as a form of systemic immunologic tolerance. However, direct examination of the antigen-specific CD4+ T cell response toward dietary antigen within the intestine itself is an essential part of this proposal. It will also be the main direction of my future investigations. Ultimately, as an academic gastroenterologist I am most interested in applying concepts derived from animal studies toward understanding and therapy of human involving immune dysregulation within the gastrointestinal tract.