Regulation of B Cell Function by Interleukin 12

说明(申请人提供)：本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。以往的实验已经证明，疫苗和外源性IL-12作为佐剂对小鼠进行鼻腔治疗可以增强系统和粘膜抗体反应，并诱导对病毒和细菌呼吸道感染的保护。进一步的结果表明，观察到的保护依赖于IL-12诱导的增强的体液免疫反应。这项建议中的研究现在旨在确定鼻腔内IL-12如何增强肺中B细胞的活性，并调查粘膜抗体与系统抗体在肺防御中的重要性。假设是IL-12刺激局部抗体的产生，主要是IgA的产生，这是对肺部感染的最初防御。IL-12还可以与疫苗/感染剂协同作用，诱导一定程度的炎症，使保护性的免疫球蛋白抗体从血液中渗出，并提供一种备份机制，以确保宿主的生存。为了检验这些概念，将在鼻腔接种IL-12后评估B细胞亚群的激活和重新进入肺内的情况。T和NK细胞以及这些细胞产生的细胞因子对增强肺B细胞活性的作用将通过基因缺陷动物和抗体耗尽/中和来确定。将结合ELISPOT和免疫组织化学分析来评估IL-12在肺和有组织的肺淋巴组织中诱导特定同种类型的局部抗体分泌细胞的能力。最后，将使用确定的抗原特异性和同种类型的杂交瘤、IgA和聚合Ig受体基因缺陷小鼠的背包模型以及被动转移特异性耗尽的IgA或IgG的抗血清来检验IgA和IgG在预防肺部细菌和病毒感染方面的相对重要性。后几个实验将被用来检验IL-12在促进免疫球蛋白抗体进入肺内的潜在作用。这项研究的直接目标是确定黏膜佐剂(如IL-12)如何增强肺部体液免疫并保护其免受感染微生物的侵袭。最终目的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.