DENDRITIC AND T CELLS IN ANTI-BACTERIAL lg RESPONSES

树突状细胞和 T 细胞在抗细菌 lg 反应中的作用

• 批准号: 7103213
• 负责人: CLIFFORD M SNAPPER
• 金额: $ 34.09万
• 依托单位: HENRY M. JACKSON FDN FOR THE ADV MIL/MED
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-04-01 至 2011-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7103213
• 关键词: CD40 molecule; MHC class II antigen; Streptococcus pneumoniae; antibacterial antibody; antibody formation; antigen presentation; bacterial antigens; bactericidal immunity; cellular immunity; cytokine; dendritic cells; helper T lymphocyte; laboratory mouse; protein biosynthesis; tissue /cell culture

DESCRIPTION (provided by applicant): Streptococcus pneumoniae (Pn) is an extracellular bacterium that is a major cause of global morbidity and mortality. Systemic adaptive immunity to Pn is mediated by antibody, especially IgG specific for the capsular polysaccharide (PS), but also for bacterial proteins. Our long-term goal is to elucidate the cellular mechanisms that underlie the distinct differences that exist between in vivo anti-PS and anti-protein Ig responses to intact Pn, as a prerequisite to the development of improved vaccines. In contrast to the current dogma, based on using purified PS antigens, that IgG anti-PS responses are T cell-independent, we demonstrated that the IgG anti-PS response to intact Pn is heavily dependent on CD4+ T cells but nevertheless, still exhibits striking differences in kinetics, generation of memory, and the functional roles of dendritic and T cells relative to the co-induced anti-protein response. In light of these data, the central hypothesis that underlies our proposed research is that differential B cell receptor signaling and/or involvement of functionally distinct B cell subsets are the key parameters that distinguish physiologic anti-PS and anti-protein Ig responses. We will demonstrate that these parameters differentially impact on 1) the temporal compartmentalization of responding B cells within the spleen, and 2) the cellular interactions of the responding B cells with other immune cell types. As a result we will provide a mechanistic basis that will elucidate the observed differences in anti-PS and anti-protein responses. The specific aims are to: 1. Determine the nature and relationships of B cell and dendritic cell subsets, and CD4+ T cells that differentially mediate in vivo anti-PS and anti-protein Ig isotype responses to systemic immunization with intact Pn. We will utilize high speed electronic cell sorting and adoptive transfer of wild-type and genetically altered immune cells combined with ELISPOT and ELISA analyses of antigen-specific Ig isotype production to accomplish this aim. 2. Determine the mechanism by which B cells, DCs, and CD4+ T cells differentially orchestrate anti-PS and anti-protein responses within a spatiotemporal context. We will utilize B cells from BCR knock-in mice with Ig specificity for Pn-derived PS or protein antigens and T cells from CD4+ TCR transgenic mice with specificity for a Pn-derived protein to accomplish this aim. These cells will be used to conduct in vitro functional studies and confocal microscopic analyses of splenic tissue sections post-immunization. These studies are the first to systematically determine the mechanisms that distinguish anti-PS from anti-protein responses to an intact bacterium and provide novel basic immunologic insights with direct relevance to the development of anti-bacterial vaccines.

描述（由申请人提供）：肺炎链球菌（Pn）是一种细胞外细菌，是全球发病和死亡的主要原因。对 Pn 的系统适应性免疫是由抗体介导的，尤其是对荚膜多糖 (PS) 具有特异性的 IgG，但也对细菌蛋白具有特异性。我们的长期目标是阐明体内抗 PS 和抗蛋白 Ig 对完整 Pn 反应之间存在明显差异的细胞机制，作为开发改进疫苗的先决条件。与当前的教条相反，基于使用纯化的 PS 抗原，IgG 抗 PS 反应是 T 细胞独立的，我们证明对完整 Pn 的 IgG 抗 PS 反应严重依赖于 CD4+ T 细胞，但仍然表现出树突状细胞和 T 细胞相对于共同诱导的抗蛋白反应，在动力学、记忆生成以及功能作用方面存在显着差异。根据这些数据，我们提出的研究的核心假设是，差异性 B 细胞受体信号传导和/或功能不同的 B 细胞亚群的参与是区分生理性抗 PS 和抗蛋白 Ig 反应的关键参数。我们将证明这些参数对 1) 脾脏内响应 B 细胞的时间分区，以及 2) 响应 B 细胞与其他免疫细胞类型的细胞相互作用产生不同的影响。因此，我们将提供一个机制基础来阐明所观察到的抗 PS 和抗蛋白反应的差异。具体目标是： 1. 确定 B 细胞和树突细胞亚群以及 CD4+ T 细胞的性质和关系，这些细胞差异介导体内抗 PS 和抗蛋白 Ig 同种型对完整 Pn 全身免疫的反应。我们将利用高速电子细胞分选和野生型和基因改造免疫细胞的过继转移，结合抗原特异性 Ig 同种型生产的 ELISPOT 和 ELISA 分析来实现这一目标。 2. 确定 B 细胞、DC 和 CD4+ T 细胞在时空背景下差异协调抗 PS 和抗蛋白反应的机制。我们将利用来自 BCR 敲入小鼠的 B 细胞（对 Pn 衍生的 PS 或蛋白抗原具有 Ig 特异性）和来自 CD4+ TCR 转基因小鼠的 T 细胞（对 Pn 衍生的蛋白具有特异性）来实现这一目标。这些细胞将用于进行免疫后脾组织切片的体外功能研究和共聚焦显微镜分析。这些研究首次系统地确定了区分抗 PS 和针对完整细菌的抗蛋白反应的机制，并提供了与抗菌疫苗的开发直接相关的新的基本免疫学见解。