Regulation of B Cell Function by Interleukin 12

描述（由申请方提供）：本项目的总体目标是确定有效接种呼吸道病原体所需的机制。先前的实验已经证明，用疫苗和作为佐剂的外源性IL-12鼻内治疗小鼠增强全身和粘膜抗体应答，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，观察到的保护作用依赖于IL-12诱导的增强的体液免疫应答。本研究旨在确定鼻内IL-12如何增强肺内B细胞活性，并研究粘膜抗体与系统性抗体在肺防御中的重要性。假设是IL-12刺激局部抗体产生，主要是伊加产生，这是肺部对感染的初始防御的原因。IL-12还可以与疫苗/感染剂协同作用以诱导一定程度的炎症，其允许保护性IgG抗体从血流渗出并提供备用机制以确保宿主的存活。为了测试这些概念，将在鼻内接种IL-12后评估B细胞亚群活化和募集到肺中。T和NK细胞以及这些细胞产生的细胞因子对增强的肺B细胞活性的贡献将使用基因缺陷动物和抗体消除/中和来确定。将通过ELISPOT和免疫组织化学分析的组合来评估IL-12诱导肺以及有组织的肺淋巴组织中确定同种型的局部抗体分泌细胞的能力。最后，将使用具有确定的抗原特异性和同种型的杂交瘤、伊加和多聚体IG受体基因缺陷小鼠以及特异性耗尽伊加或IgG的抗血清的被动转移的背包模型来检查伊加相对于IgG对于肺中的细菌和病毒感染的保护的相对重要性。将进行这些后面的实验以检查IL-12在促进IgG抗体渗出到肺中的潜在作用。该研究的直接目标是确定粘膜佐剂如IL-12如何增强肺体液免疫和对感染性微生物的保护。最终目标是利用所获得的信息，以了解诱导保护性肺免疫的要求，并设计有效的粘膜疫苗佐剂用于人类。

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.