Chemokines and Lymphoid Tissue Organization and Function

描述(由申请人提供)：体液免疫反应对于抵御病原体至关重要，也是自身免疫和过敏性疾病发病的原因之一。尽管它们很重要，但关于抗体反应是如何进行的，基本问题仍然存在。这笔赠款的一个主要重点是确定淋巴器官中促进抗体反应的趋化因子和相关组织者线索的特征。与当前建议相关的主要发现是：确定淋巴结被膜下窦(SCS)巨噬细胞是B细胞与调理抗原相遇的部位；证明B细胞作为抗原运输细胞；CXCR4和CXCR5作为生发中心(GC)的组织者的特征；GC中细胞迁移动力学的可视化；毛囊-T区边界和GC中B细胞-T细胞接触的测量，从而证明GC B细胞的选择可能部分是通过竞争T细胞帮助发生的。基于这些发现，我们建议将应用重点放在以下三个具体目标上。首先，我们寻求进一步评估SCS巨噬细胞如何利用荧光显微镜、流式细胞术和双光子成像方法捕获抗原并与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巨噬细胞定位所需的趋化因子。B细胞与滤泡树突状细胞的相互作用也将被可视化。其次，我们的目标是描述与在生发中心(GC)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打B细胞的采用转移方法来研究干扰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，我们将研究在GC B细胞中发现转录上调的另一种G蛋白偶联受体在GC反应中的作用。这些研究应该有助于更好地理解B细胞是如何遇到抗原和进行选择的，这些知识对改进疫苗的开发具有意义，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。

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.