Imaging and Function of the Immunological Synapse

描述（由申请人提供）：T淋巴细胞识别抗原，即与抗原呈递细胞（APC）表面MHC分子结合的小肽。除了T细胞抗原受体和负载肽的MHC之外，数十种其他细胞表面分子在决定T细胞/APC相互作用的结果中发挥必要或调节作用。抗原识别伴随着这些分子的大规模的细胞因子依赖性重排，以在T细胞和APC之间形成被称为“免疫突触”的有组织的接触界面。许多实验室正在研究突触提供或调节T细胞完全激活所需信号的方式。在这项授权申请中，重点是免疫突触在将效应功能从CD 4 T细胞传递到APC中的作用，使用FasL（CD 178）和CD 40 L（CD 154）作为膜结合效应细胞因子的原型。由于大多数在体内的相互作用可能太短，允许从头合成的效应细胞因子，拟议的实验检查的可能性，预先形成的，细胞内储存的FasL和CD 40 L在T细胞/APC相互作用中发挥重要作用。CD 40 L首先被鉴定为细胞接触依赖性CD 4 T细胞帮助B细胞的介体，并且此后已显示为巨噬细胞的有效激活剂，用于杀死树突细胞的细胞内病原体，以引发CD 4和CD 8 T细胞中的效应子功能和记忆。FasL是CD 4和CD 8 T细胞接触依赖性杀伤的主要介质，并在活化诱导的细胞死亡期间通过T细胞自杀或自相残杀调节T细胞应答。 使用最先进的显微镜和体外和体内功能测定的组合，该提议将测试以下假设：预形成的CD 40 L和FasL储存在大多数致敏的CD 4效应和记忆T细胞的分泌溶酶体中，通过免疫突触快速递送到B细胞和其他APC，并且具有与新合成的CD 40 L和FasL不同的重要功能结果。它还将研究由1型和2型辅助T细胞形成的突触之间的结构差异，并测试以下假设：由CD 4 T细胞形成的成熟免疫突触中粘附分子环的功能是确保效应分子向APC的抗原特异性递送，并防止递送到周围的旁观者细胞。 公共卫生相关性：T淋巴细胞仅识别其他细胞表面的抗原，称为抗原呈递细胞（APC），并通过分泌有效的细胞因子和其他效应分子发挥其作用。本申请的目的是了解各种CD 4 T细胞如何将效应细胞因子递送至APC。该应用程序的重点是FasL（CD 178）和CD 40 L（CD 154），这是控制健康和疾病适应性免疫反应的关键膜结合细胞因子。拟议的实验将有助于基本了解调节CD 4 T细胞效应器功能，这反过来又将在移植，自身免疫，过敏，癌症免疫治疗和传染病控制中具有与公共卫生相关的应用。

DESCRIPTION (provided by applicant): T lymphocytes recognize antigen as small peptides bound to MHC molecules on the surface of antigen presenting cells (APC). In addition to the T cell antigen receptor and peptide-loaded MHC, dozens of other cell surface molecules play necessary or modulating roles in determining the outcome of the T cell/APC interaction. Antigen recognition is accompanied by large-scale, cytoskeleton-dependent rearrangements of these molecules to form an organized contact interface between the T cell and the APC termed the "immunological synapse". Many laboratories are investigating the ways in which the synapse may provide or regulate the signals necessary for full T cell activation. In this grant application, the focus is on the role of the immunological synapse in the delivery of effector functions from CD4 T cells to APC, using FasL (CD178) and CD40L (CD154) as prototypes of membrane-bound effector cytokines. Since most interactions in vivo may be too short to allow for de novo synthesis of effector cytokines, the proposed experiments examine the possibility that preformed, intracellular stores of FasL and CD40L play important roles in T cell/APC interactions. CD40L was first identified as the mediator of cell contact-dependent CD4 T cell help for B cells, and has since been shown to be a potent activator of macrophages for killing of intracellular pathogens of dendritic cells for priming effector functions and memory in CD4 and CD8 T cells. FasL is a principal mediator of contact-dependent killing by CD4 and CD8 T cells, and regulates T cell responses through T cell suicide or fratricide during activation-induced cell death. Using a combination of state-of-the-art microscopy and functional assays in vitro and in vivo, this proposal will test the hypothesis that pre-formed CD40L and FasL are stored in secretory lysosomes in most primed CD4 effector and memory T cells, are delivered rapidly through the immunological synapse to B cells and other APC in transient antigen-specific interactions, and have important functional consequences distinct from those of newly synthesized CD40L and FasL. It will also investigate structural difference between synapses formed by type 1 and type 2 helper T cells, and test the hypothesis that the function of the ring of adhesion molecules in the mature immunological synapse formed by CD4 T cells is to ensure antigen-specific delivery of effector molecules to the APC and prevent delivery to surrounding bystander cells. PUBLIC HEALTH RELEVANCE: T lymphocytes recognize antigen only on the surface of other cells, called antigen presenting cells (APC), and exert their effects by secreting potent cytokines and other effector molecules. The goal of this application is to understand how various kinds of CD4 T cells deliver effector cytokines to APC. The application is focused on FasL (CD178) and CD40L (CD154), key membrane-bound cytokines which control the adaptive immune response in health and disease. The proposed experiments will contribute to a basic understanding of the regulation CD4 T cell effector functions, which in turn will have public health-related applications in transplantation, autoimmunity, allergy, cancer immunotherapy, and control of infectious diseases.