IL-12 as an immunopotentiator in leishmaniasis

描述（由申请人提供）：小鼠中的实验性利什曼原虫主要感染已被广泛用于了解细胞介导的免疫（CMI）如何发展，并具体定义决定T细胞活化后是否观察到Th1或Th2应答的因素。这些研究已经清楚地显示了IL-12在抗性和Th1应答的发展中的重要作用。然而，尽管我们对与Th1反应的发展相关的事件的了解大大增加，但对管理CMI维持的规则却知之甚少。我们的实验室最近表明，IL-12不仅需要启动Thi细胞发育，而且还需要维持这种反应。本研究试图确定IL-12是如何参与维持CMI的，从而更广泛地研究免疫记忆在L.治愈的老鼠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久性的作用（目标2），和辅助细胞-特别是树突状细胞-既呈递抗原，又影响发育的T细胞的性质（目标3）。该提议的工作假设是CMI需要来自非极化T细胞库的Thi群体的不断更新。为了验证这一假设，提出了一系列过继转移实验，既有常规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。将在受体小鼠中追踪供体细胞以评估它们的命运。寄生虫持续性的作用分析将使用L。感染小鼠但不能存活的主要（dhfr-ts-）胸苷营养缺陷型。最后，抗原呈递的作用将通过表征与抗性相关的树突状细胞应答来评估。该实验室的初步研究表明，免疫力不需要CD4O-CD4OL相互作用，为此，将检测TRANCE的代偿作用。总的来说，这些实验应该提供一个清晰的图片之间的动态相互作用的T细胞，树突状细胞和持久的寄生虫，需要维持细胞介导的免疫力。

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.