Kupffer cell mediated deletion of activated CD8+ T cells

描述(由申请人提供)： 肝脏的免疫反应经常是次优的。临床上的例子包括感染乙肝病毒和丙型肝炎病毒，以及对口服和同种异体抗原的耐受性。我们对激活的CD8+T细胞进入肝脏后的命运很感兴趣，并证明了：i)肝脏保留了进入肝脏的激活的CD8+T细胞，即使在没有特定多肽的情况下也是如此；ii)保留的细胞与Kupffer细胞(KC)物理接触；iii)经历细胞凋亡。在事件I和事件III之间，人们对保留的CD8+T细胞知之甚少。在KO8奖的头两年产生的初步数据中，我们表明：a)进入肝脏的激活的CD8+T细胞在48小时内经历了大约7倍的扩张；b)随后由于肝脏内的凋亡，在接下来的5天里逐渐减少；c)特定多肽的存在导致保留的CD8+T细胞库显著减少，原因是细胞凋亡增加；d)在没有KC的情况下，特定的多肽不会导致激活的CD8+T细胞数量减少。这些结果表明，KC是抗原诱导的肝内CD8+T细胞缺失所必需的，并与两个假设一致：假设A：KC的抗原提呈与抗原诱导的肝内CD8+T细胞的缺失有关。假设B：非KC上的抗原提呈负责抗原诱导的肝内CD8+T细胞的删除，但KC在传递凋亡信号方面具有重要作用。 具体目标1：确定KC特异性抑制体内I类MHC加工是否能阻断肝内CD8+T细胞的凋亡。 特异性AIMS 2a)确定KC在体外向激活的CD8+T细胞提呈抗原是否会导致CD8+T细胞凋亡。 2B)确定Kupffer细胞ICAM-1、CD95-L、吲哚胺双加氧酶和Galectin-1是否在CD8+T细胞的牢固黏附和凋亡中起重要作用。 这些目标将通过使用KC中MHC I类递呈被抑制的转基因小鼠来实现，并通过开发体外系统来测试特定靶2b分子在KC介导的细胞凋亡中的作用。

DESCRIPTION (provided by applicant): The immune response in the liver is frequently sub-optimal. Clinical examples of this are infection with hepatitis B and C viruses, as well as tolerance to oral and alloantigens. We are interested in the fate of activated CD8+ T cells after they have entered the liver and have demonstrated that i) the liver retains activated CD8+ T cells that enter it, even in the absence of specific peptide ii) the retained cells are in physical contact with Kupffer ceils (KC) and iii) undergo apoptosis. Between events i and iii very little is known about the retained CD8+ T cells. In the preliminary data generated in the first two years of the KO8 award we show that a) activated CD8+ T cells on entering the liver undergo approximately seven fold expansion over 48 hours b) this is followed by a gradual decrease over the next 5 days due to intrahepatic apoptosis c) the presence of specific peptide results in significant reduction in the retained CD8+ T cell pool due to enhanced apoptosis d) in the absence of KC, specific peptide does not results in reduction in the activated CD8+ T cell population. These results demonstrate that KC are required for antigen induced deletion of intrahepatic activated CD8+ T cells, and are consistent with two hypothesis: Hypothesis A: Antigen presentation by KC is responsible for antigen induced deletion of intraheptic CD8+ T cells. Hypothesis B: Antigen presentation on non-KC is responsible for antigen induced deletion of intrahepatic CD8+ T cells, but KC have an important role in delivering the apoptotic signal. Specific aim 1: Determine if KC specific inhibition of class I MHC processing in-vivo blocks apoptosis of intrahepatic CD8+ T cells. Specific aims 2a) Determine if antigen presentation by KC to activated CD8+ T cells in-vitro results in CD8+ T cell apoptosis. 2b) Determine if Kupffer cell ICAM-1, CD95-L, indoleamine dioxygenase and galectin-1 are important in the firm adhesion and apoptosis of CD8+ T cells. These aims will be achieved by using transgenic mice in which MHC class I presentation is inhibited in KC, and by developing in-vitro systems in which the role of the molecules in specific aim 2b in KC mediated apoptosis is tested.