Regulation of B Cell Function by Interleukin 12

描述（由申请人提供）：该项目的总体目标是确定有效接种呼吸道病原体疫苗所需的机制。先前的实验表明，用疫苗和外源性 IL-12 作为佐剂对小鼠进行鼻内治疗可增强全身和粘膜抗体反应，并诱导针对病毒和细菌呼吸道感染的保护。进一步的结果表明，观察到的保护作用取决于 IL-12 诱导的增强体液免疫反应。该提案中的研究现在旨在确定鼻内 IL-12 如何增强肺部 B 细胞活性，并研究粘膜抗体与全身抗体在肺部防御中的重要性。假设 IL-12 刺激局部抗体产生，主要是 IgA 产生，这负责肺部感染的初步防御。 IL-12 还可以与疫苗/感染剂协同作用，诱导一定程度的炎症，使保护性 IgG 抗体从血流中渗出，并提供后备机制以确保宿主的生存。为了测试这些概念，将在鼻内接种 IL-12 后评估 B 细胞亚群的激活和招募到肺部的情况。 T 细胞和 NK 细胞以及这些细胞产生的细胞因子对增强肺 B 细胞活性的贡献将使用基因缺陷动物和抗体耗竭/中和来确定。 IL-12 在肺部以及有组织的肺淋巴组织中诱导特定同种型局部抗体分泌细胞的能力将通过 ELISPOT 和免疫组织化学分析相结合进行评估。最后，将使用具有确定抗原特异性和同种型的杂交瘤、IgA 和聚合 Ig 受体基因缺陷小鼠的背包模型以及专门去除 IgA 或 IgG 的抗血清的被动转移来检查 IgA 与 IgG 对于防止肺部细菌和病毒感染的相对重要性。后面这些实验将用于检查 IL-12 在促进 IgG 抗体渗出至肺部中的潜在作用。该研究的直接目标是确定 IL-12 等粘膜佐剂如何增强肺体液免疫和针对传染性微生物的保护。最终目标是利用所获得的信息来了解诱导保护性肺部免疫的要求并设计用于人类的有效粘膜疫苗佐剂。

DESCRIPTION (provided by applicant): The overall objective of this project is to determine the mechanisms required for effective vaccination against respiratory pathogens. Previous experiments have demonstrated that intranasal treatment of mice with vaccine and exogenous IL-12 as adjuvant enhances systemic and mucosal antibody responses, and induces protection against viral and bacterial respiratory infections. Further results have indicated that the observed protection is dependent upon the augmented humoral immune response induced by IL-12. Studies in this proposal are now designed to determine how intranasal IL-12 enhances B cell activity in the lung and to investigate the importance of mucosal versus systemic antibody in pulmonary defense. The hypothesis is that IL-12 stimulates local antibody production, primarily IgA production, and this is responsible for initial defense against infection in the lung. IL-12 may also act synergistically with vaccines/infectious agents to induce a degree of inflammation that allows protective IgG antibody to transudate from the bloodstream and provide a back-up mechanism to ensure survival of the host. To test these concepts, B cell subset activation and recruitment into the lung will be assessed after intranasal vaccination ¿ IL-12. The contributions of T and NK cells, and the cytokines produced by these cells, to enhanced pulmonary B cell activity will be determined using gene deficient animals and antibody depletion/neutralization. The ability of IL-12 to induce localized antibody secreting cells of defined isotype in the lung as well as organized pulmonary lymphoid tissue will be assessed by a combination of ELISPOT and immunohistochemical analyses. Finally, the relative importance of IgA versus IgG for protection against bacterial and viral infection in the lung will be examined using the backpack model with hybridomas of defined antigen specificity and isotype, IgA and polymeric Ig receptor gene deficient mice, and passive transfer of antisera specifically depleted of IgA or IgG. These latter experiments will be performed to examine the potential role of IL-12 in promoting transudation of IgG antibody into the lung. The immediate goal of the study is to determine how a mucosal adjuvant such as IL-12 can enhance lung humoral immunity and protection against infectious microbes. The ultimate goal is to exploit the information obtained in order to understand the requirements for induction of protective pulmonary immunity and to design effective mucosal vaccine adjuvants for use in humans.