IL-12 as an immunopotentiator in leishmaniasis

描述(由申请人提供)：实验性利什曼原虫在小鼠中的主要感染已被广泛用于了解细胞介导的免疫(CMI)是如何发展的，并具体定义决定T细胞激活后观察到Th1或Th2反应的因素。这类研究清楚地表明，IL-12在抵抗和Th1反应的发展中起着重要作用。然而，尽管我们对与Th1反应的发展相关的事件的了解有了很大的增加，但对CMI维持的规则了解很少。我们的实验室最近表明，IL-12不仅是启动THI细胞发育所必需的，而且也是维持这种反应所必需的。这项建议试图确定IL-12如何参与维持CMI，并通过这样做将更广泛地研究大型乳杆菌治愈小鼠的免疫记忆是如何工作的。我们的具体目标是解决CMI的三个关键组成部分：记忆T细胞功能(目标1)，抗原--在这种情况下，寄生虫持续存在的作用(目标2)，以及辅助细胞--特别是树突状细胞--既提供抗原，又影响所发育的T细胞的性质(目标3)。这一建议的工作假设是，CMI需要从非极化的T细胞池中不断更新THI群体。为了验证这一假设，提出了一系列过继转移实验，既有传统T细胞，也有识别利什曼原虫和非利什曼原虫抗原的TCR转基因T细胞。供体细胞将在受体小鼠体内进行跟踪，以评估它们的命运。对寄生虫持久性的作用的分析将使用一种大型乳杆菌(dhfr-ts-)胸腺苷营养缺陷体，它感染小鼠，但无法存活。最后，将通过表征与耐药性相关的树突状细胞反应来评估抗原提呈的作用。该实验室的初步研究表明，免疫并不需要CD4O-CD4OL相互作用，为此，将测试催眠的代偿作用。总体而言，这些实验应该清楚地描绘出维持细胞免疫所需的T细胞、树突状细胞和持续寄生虫之间的动态相互作用。

DESCRIPTION (provided by the applicant): Experimental Leishmania major infections in mice have been used extensively to understand how cell-mediated immunity (CMI) develops, and to specifically define the factors that dictate whether a Th1 or Th2 response is observed after activation of T cells. Such studies have clearly shown an important role for IL-12 in the development of resistance and a Th1 response. However, despite a great increase in our knowledge of the events that are associated with the development of Th1 responses, little is understood about the rules that govern the maintenance of CMI. Our laboratory has recently shown that IL- 12 is required not only to initiate Thi cell development, but also to maintain this response. This proposal seeks to determine how IL-12 participates in maintaining CMI, and in so doing will more broadly investigate how immunologic memory works in L. major healed mice. Our specific aims address the three critical components for CMI: memory T cell function (Aim 1), the antigen-in this case the role of parasite persistence (Aim 2), and the accessory cells-specifically dendritic cells-that both present antigen and influence the nature of the T cells that develop (Aim 3). The working hypothesis of this proposal is that CMI requires the constant renewal of the Thi population from a non-polarized pool of T cells. To test this hypothesis a series of adoptive transfer experiments are proposed, both with conventional T cells, as well as TCR transgenic T cells recognizing Leishmania and non-Leishmania antigens. The donor cells will be tracked in the recipient mice to assess their fate. An analysis of the role of parasite persistence will use a L. major (dhfr-ts-) thymidine auxotroph that infects mice, but fails to survive. Finally, the role of antigen presentation will be assessed by characterizing the dendritic cell response associated with resistance. Preliminary studies from this laboratory demonstrated that CD4O-CD4OL interactions are not required for immunity, and in this aim, the compensatory role of TRANCE will be tested. Overall, these experiments should provide a clear picture of the dynamic interactions between T cells, dendritic cells and persisting parasites that are required to maintain cell-mediated immunity.