CELLULAR AND MOLECULAR BASIS FOR THE IGA RESPONSE

IGA 反应的细胞和分子基础

• 批准号: 3128353
• 负责人: Jerry R McGhee
• 金额: $ 18.76万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 1982
• 资助国家: 美国
• 起止时间: 1982-09-30 至 1994-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3128353
• 关键词: B lymphocyte; Peyer's patches; antibody formation; antigen presentation; cell cell interaction; cell differentiation; cell transformation; dendritic cells; gene rearrangement; helper T lymphocyte; hybridomas; immunoglobulin A; immunoglobulin M; in situ hybridization; interferons; interleukin 2; interleukin 5; interleukin 6; laboratory mouse; laboratory rabbit; leukocyte activation /transformation; lymphatic tissue; mouse sarcoma virus; secretory immune system; tissue /cell culture; transforming growth factors

The broad objective of this research is to elucidate the molecular events involved in regulation of lgA responses at mucosal sites. Our studies have shown that higher mammals possess a common mucosal immune system in which ingested antigens sensitize B and T cells in gut-associated lymphoreticular tissue (GALT), e.g., the Peyer's patches (PP). T helper (Th) cells regulate the inductive phase in PP, and it is thought that Th and lgA-committed B cells home to diverse mucosal effector regions such as the lamina propria of the gastrointestinal (Gi) tract for lgA synthesis. However, the precise mechanisms involved in regulation of this response remain unknown. Our past work has shown that PP dendritic cell (DC)-T cell mixtures significantly enhance lgA synthesis. Further, antigenspecific PP Th cell clones were shown to selectively support lgA responses, clearly indicating that GALT is an lgA inductive site. Recent studies have shown that recombinant interleukins, especially lL-5 and lL- 6, support enhance lgA synthesis in PP B cell cultures. The lL-5- and lL- 6-induced increase in lgA synthesis was confined to nongerminal center, surface lgA-positive (sigA+) B cells. This subset also repopulates lamina propria regions upon adoptive transfer to SCID mice which suggests that mature sigA+ B cells are sensitive to cytokines when they exit GALT. In this new renewal application we will define the T cell and cytokine requirements for sigM+ B cell switches to sigA+ in PP germinal centers by using highly purified B cell subsets and virus-transformed B cell lines from GALT. We will continue our studies to define the cytokine events involved in B cell activation, division and terminal differentiation to lgA synthesis, with special emphasis on cloned PP Th2 cells and lL-5 and lL-6. We will extensively use the single-cell ELISPOT assay to determine the relative frequencies of Th1 (lL-2 and lFNgamma) and Th2 (lL-5 and lL- 6) cells in GALT and lamina propria regions, for their roles in production of switch cytokines (TGFbeta) and cytokines inducing terminal differentiation to lgA synthesis (lL-5 and lL-6). We will extensively use two animals models to insure that the in vitro effects of cytokines represent the actual events that occur in vivo. Mice chronically depleted of CD4+ Th cells by immunotoxin- conjugated anti-CD4 mAbs which inactivate ribosomes and protein synthesis in CD4+ T cells will be used to show that the development of lgA plasma cells in effector mucosal sites is T cell dependent, while SCID mice will be used as adoptive hosts for cloned PP Th cells and slgA+ B cell subsets that respond to interleukins and that repopulate mucosal sites. We will study the antigen presenting cell functions of PP slgA+ and slgA- B cells and DC for effective induction of lgA responses. Finally, we will determine the mechanism(s) involved in PP DC-Th cell induction of pre-B B cell maturation in GALT, including a possible role for lL-7.

这项研究的广泛目标是阐明分子事件 参与调节粘膜部位的lgA反应。 我们的研究 研究表明，高等哺乳动物具有共同的粘膜免疫系统 摄入的抗原会使肠道相关的 B 细胞和 T 细胞变得敏感 淋巴网状组织 (GALT)，例如派尔氏淋巴结 (PP)。 T帮手 (Th) 细胞调节 PP 的诱导期，人们认为 Th 和IgA定向B细胞归巢于不同的粘膜效应区域，例如 胃肠道 (Gi) 固有层负责 LGA 合成。 然而，调节这种反应的精确机制 仍然未知。 我们过去的工作表明，PP树突状细胞（DC）-T 细胞混合物显着增强 IgA 合成。 更远， 抗原特异性 PP Th 细胞克隆被证明可以选择性支持 IgA 响应，清楚地表明 GALT 是 lgA 诱导位点。 最近的 研究表明重组白细胞介素，特别是lL-5和lL- 6、支持增强PP B细胞培养物中的IgA合成。 lL-5- 和 lL- 6诱导的IgA合成增加仅限于非生发中心， 表面 lgA 阳性 (sigA+) B 细胞。 该子集也重新填充层板 过继转移至 SCID 小鼠后的固有区域表明 成熟的 sigA+ B 细胞退出 GALT 时对细胞因子敏感。 在 在这个新的更新应用程序中，我们将定义 T 细胞和细胞因子 sigM+ 的要求 B 细胞在 PP 生发中心转变为 sigA+ 使用高度纯化的 B 细胞亚群和病毒转化的 B 细胞系 来自高尔特。 我们将继续研究来定义细胞因子事件 参与 B 细胞的激活、分裂和终末分化 LGA 合成，特别强调克隆的 PP Th2 细胞和 lL-5 和 lL-6。 我们将广泛使用单细胞 ELISPOT 测定来确定 Th1（lL-2 和 lFNgamma）和 Th2（lL-5 和 lL- 6) GALT 和固有层区域的细胞在生产中的作用 开关细胞因子 (TGFbeta) 和细胞因子诱导末端 分化为lgA合成（lL-5和lL-6）。 我们将广泛使用 两种动物模型以确保细胞因子的体外作用 代表体内发生的实际事件。 小鼠长期耗竭 通过免疫毒素偶联的抗 CD4 mAb 来抑制 CD4+ Th 细胞， 灭活 CD4+ T 细胞中的核糖体和蛋白质合成将用于 表明效应粘膜中lgA浆细胞的发育 位点依赖于 T 细胞，而 SCID 小鼠将用作收养宿主 对于克隆的 PP Th 细胞和 slgA+ B 细胞亚群有反应 白介素并重新填充粘膜部位。 我们将研究抗原 展示 PP slgA+ 和 slgA- B 细胞和 DC 的细胞功能 有效诱导lgA反应。 最后，我们将确定 参与 PP DC-Th 细胞诱导前 B B 细胞的机制 GALT 中的成熟，包括 lL-7 的可能作用。