Chemokines and Lymphoid Tissue Organization and Function

描述（由申请方提供）：体液免疫应答对于抵抗病原体至关重要，并且是自身免疫性和过敏性疾病发病机制的原因。尽管它们很重要，但关于抗体反应如何发生的基本问题仍然存在。这项资助的一个主要重点是描述淋巴器官中促进抗体反应的趋化因子和相关组织因子。与当前提议相关的关键发现是：鉴定淋巴结被膜下窦（SCS）巨噬细胞作为B细胞与调理素抗原相遇的位点;证明B细胞作为抗原转运细胞;表征CXCR 4和CXCR 5作为生殖中心（GC）的组织者;观察GC中的细胞迁移动力学;在滤泡-T区边界和GC中的B细胞-T细胞接触的测量导致GC B细胞选择可能部分通过竞争T细胞帮助而发生的证据。基于这些发现，我们建议将应用程序集中在以下三个具体目标上。第一，我们试图进一步评估SCS巨噬细胞如何捕获抗原，并使用荧光显微镜，流式细胞术和双光子成像方法与B细胞相互作用。此外，我们将通过基因表达研究和基因靶向小鼠的分析来确定SCS巨噬细胞定位的趋化因子需求。B细胞与滤泡树突细胞的相互作用也将被可视化。第二，我们的目标是表征与在German Center（GC）中选择高亲和力B细胞相关的细胞事件。我们将使用免疫球蛋白“敲入”B细胞的过继转移方法来研究破坏GC B细胞定位的趋化因子受体缺陷对抗体亲和力成熟的影响。第三，我们将进一步研究G蛋白偶联受体在GC反应中的作用，该受体在GC B细胞中被转录上调。这些研究应该导致更好地理解B细胞如何遇到抗原并进行选择，这些知识对改进疫苗的开发具有影响，并可能提出减少对自身抗原或过敏原的不必要反应的新方法。公共卫生相关性：体液免疫应答对于抵抗病原体是至关重要的，并且是自身免疫性和过敏性疾病的发病机制的原因。拟议的研究应导致更好地了解B细胞如何遇到抗原和经历选择，知识的发展，改进疫苗的影响，并可能建议新的方法，减少不必要的反应，自身抗原或过敏原。

DESCRIPTION (provided by applicant): Humoral immune responses are critical for protection against pathogens and are a cause of pathogenesis in autoimmune and allergic diseases. Despite their importance, fundamental questions remain regarding how antibody responses are mounted. A major focus of this grant has been to characterize the chemokines and related organizer cues in lymphoid organs that facilitate antibody responses. Key findings pertinent to the current proposal have been: identification of lymph node subcapsular sinus (SCS) macrophages as a site of B cell encounter with opsonized antigen; demonstration that B cells function as antigen transport cells; characterization of CXCR4 and CXCR5 as organizers of the germinal center (GC); visualization of cell migration dynamics in the GC; measurement of B cell -T cell contacts at the follicle-T zone boundary and in the GC leading to evidence that GC B cell selection may occur in part through competition for T cell help. Based on these findings we propose to focus the application on the following three specific aims. One, we seek to further assess how SCS macrophages capture antigen and interact with B cells using fluorescence microscopy, flow cytometry and two-photon imaging approaches. In addition, we will identify chemokine requirements for SCS macrophage positioning using gene expression studies and analysis of gene targeted mice. B cell interaction with follicular dendritic cells will also be visualized. Second we aim to characterize cellular events associated with selection of high affinity B cells in the Germinal Center (GC). We will use adoptive transfer approaches with immunoglobulin `knockin' B cells to study the impact on antibody affinity maturation of chemokine receptor deficiencies that disrupt GC B cell positioning. Third, we will examine the role in the GC response of a further G-protein coupled receptor found to be transcriptionally upregulated in GC B cells. These studies should lead to an improved understanding of how B cells encounter antigen and undergo selection, knowledge that has implications for development of improved vaccines and may suggest novel approaches for reducing unwanted responses to autoantigens or allergens. Public Health Relevance: Humoral immune responses are critical for protection against pathogens and are a cause of pathogenesis in autoimmune and allergic diseases. The proposed studies should lead to an improved understanding of how B cells encounter antigen and undergo selection, knowledge that has implications for development of improved vaccines and may suggest novel approaches for reducing unwanted responses to autoantigens or allergens.