MECHANISMS OF B CELL ACTIVATION BY CLASS II MHC AND CD40

II 类 MHC 和 CD40 激活 B 细胞的机制

• 批准号: 2882158
• 负责人: GAIL A. BISHOP
• 金额: $ 20.02万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-09-01 至 2001-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2882158
• 关键词: B lymphocyte; CD40 molecule; MHC class II antigen; T lymphocyte; biological signal transduction; cell cell interaction; chimeric proteins; immunoglobulins; laboratory mouse; leukocyte activation /transformation; membrane proteins; polymerase chain reaction; protein structure function; protein tyrosine kinase; tissue /cell culture; transfection

B cell activation is a highly regulated process involving multiple different signals. The net effect of these interacting signal pathways is to determine the B cell response to recognition of antigen. A detailed understanding of how signal transducing molecules on B cells work is essential to understanding, and potentially controlling, B cell proliferation and antibody secretion. Thus, specifically targeted therapies for B cell hyperproliferative diseases, such as B cell malignancies, require an understanding of how B cell signaling pathways function and interact. The majority of B lymphocyte activation events involve specific binding of B cell membrane Ig to antigen, and interaction with T helper cells via both polymorphic and non-polymorphic transmembrane molecules. Nonspecific B cell activation signals can be provided by T cell-secreted lymphokines and nonpolymorphic T cell membrane molecules, such as CD40 ligand (CD40L) on activated T cells. However, it is our hypothesis that specific interactions with antigen prepare B cells to respond optimally to subsequent T cell-mediated signals, and specific interactions between T cell receptors and B cell MHC class II molecules preserve the specificity of T cell-B cell interactions. Our laboratory and others have demonstrated that class II MHC molecules preserve the specificity of T cell-B interactions. Our laboratory and others have demonstrated that class II MHC molecules deliver regulatory signals to B lymphocytes, and that these signals synergize with signals delivered by the binding of antigen to membrane ig. In addition, class II-mediated signals counteract antigen-mediated anergy signals, which may be a mechanism by which T cells stimulate B cell hyperproliferation in malignancy and autoimmune disease. More recently, we have obtained data indicating that signals delivered via class II cooperate with signals delivered to B cells by the binding of T cell CD40L B cell CD40. We thus believe that signals delivered by antigen and cognate interaction with T cells (i.e., signals delivered by binding of mig and MHC class II molecules) increase the effectiveness of CD40-mediated signals following T cell activation, and decrease the probability of inappropriate B cell activation through "bystander" effects. Thr proposed experiments will test determine the molecular basis of this interaction between signal receptors. Three major experimental approaches will be used to test our hypotheses. First, we will use recombinant DNA technology to produce alterations in the genes encoding MHC class II and CD40 molecules. Using B cell lines as models, we will introduce these altered genes and study the signaling function of the proteins they produce, to define a detailed relationship between structure and function for these signaling molecules. Second, we will use state-of=- the-art biochemical signaling assays to identify the intracellular events which result from signaling via class II MHC and CD40 molecules. Finally, we will perform in vitro and in vivo experiments examining the molecular mechanisms by which these signals cooperate in the regulation of B cell activation. The combination of these three approaches will yield a better understanding of how to manipulate athe process of B cell activation, through better understanding of the mechanism of, and interactions between the component parts of the process.

B 细胞激活是一个高度调控的过程，涉及多种因素 不同的信号。 这些相互作用的信号通路的净效应是 确定 B 细胞对抗原识别的反应。 详细的 了解 B 细胞上的信号转导分子如何发挥作用 对于理解和潜在控制 B 细胞至关重要 增殖和抗体分泌。 因此，专门针对 B细胞过度增殖性疾病的治疗，例如B细胞 恶性肿瘤，需要了解 B 细胞信号通路如何 功能并相互作用。 大多数 B 淋巴细胞激活事件 涉及 B 细胞膜 Ig 与抗原的特异性结合以及相互作用 通过多态性和非多态性跨膜与 T 辅助细胞 分子。 非特异性 B 细胞激活信号可由 T 提供 细胞分泌的淋巴因子和非多态性 T 细胞膜分子， 例如激活的 T 细胞上的 CD40 配体 (CD40L)。 然而，这是我们的 假设与抗原的特异性相互作用使 B 细胞能够 对随后的 T 细胞介导的信号做出最佳反应，并且具有特异性 T 细胞受体和 B 细胞 MHC II 类分子之间的相互作用 保留 T 细胞-B 细胞相互作用的特异性。 我们的实验室和 其他人已经证明 II 类 MHC 分子可以保护 T 细胞-B 相互作用的特异性。 我们实验室和其他实验室有 证明 II 类 MHC 分子向 B 传递调节信号 淋巴细胞，并且这些信号与淋巴细胞传递的信号协同作用 抗原与膜的结合 ig。 此外，II类介导的信号 抵消抗原介导的无反应信号，这可能是以下机制： 哪些 T 细胞在恶性肿瘤中刺激 B 细胞过度增殖， 自身免疫性疾病。 最近，我们获得的数据表明 通过 II 类传递的信号与传递至 B 细胞的信号配合 通过 T 细胞 CD40L B 细胞 CD40 的结合。 因此我们认为信号 通过抗原传递以及与 T 细胞的同源相互作用（即信号 通过 mig 和 MHC II 类分子的结合传递）增加 T 细胞激活后 CD40 介导的信号的有效性，以及 通过以下方式降低 B 细胞不适当激活的可能性 “旁观者”效应。 提议的实验将测试确定 信号受体之间这种相互作用的分子基础。 三大 实验方法将用于检验我们的假设。 首先，我们 将使用重组DNA技术来改变基因 编码 MHC II 类和 CD40 分子。 我们以 B 细胞系为模型 将引入这些改变的基因并研究其信号功能 它们产生的蛋白质，定义结构之间的详细关系 以及这些信号分子的功能。 其次，我们将使用 state-of=- 最先进的生化信号分析来识别细胞内事件 这是由 II 类 MHC 和 CD40 分子的信号传导产生的。 最后， 我们将进行体外和体内实验来检查分子 这些信号协同调节 B 细胞的机制 激活。 这三种方法的结合将产生更好的结果 了解如何操纵 B 细胞激活过程， 通过更好地理解其机制以及它们之间的相互作用 流程的组成部分。