ROLE OF NON-CLASSICAL MHC CLASS I AND HSPs IN IMMUNITY

描述（由申请人提供）：热休克蛋白（hsps） gp96和hsp70唤起有效的抗肿瘤免疫的独特能力似乎依赖于两个主要特性：(1)它们的肽依赖能力，通过APC的受体介导的内吞作用和APC的MHC经典la类分子的表现，来伴随并引发针对抗原肽的适应性CTL反应；(2)它们的肽独立能力来激活APC。抗肿瘤ctl被认为是热休克蛋白介导反应的主要效应物。然而，越来越多的证据表明NK细胞和其他识别非经典Ib类分子的不太明确的细胞毒性细胞类型也可能发挥关键作用。由于肿瘤通常下调MHC la类的表达，从而逃避免疫监视，因此我们观察到这些热休克蛋白可以产生不受la类限制的抗肿瘤免疫反应，但可能涉及Ib类分子，显然值得进一步探索。因此，我们提出验证hsps可以刺激经典的la类无限制ctl （ccu - ctl）的假设，其效应函数涉及Ib类分子。为此，我们在青蛙Xenopus中开发了一种独特而通用的实验模型系统，其特征是次要和主要组织相容性定义的克隆动物和MHC类la阴性可移植胸腺淋巴瘤。该模型将用于通过体外杀伤试验、体内过继细胞转移和抗体消耗方案来评估gp96和hsp70产生抗肿瘤肽依赖性CTL效应反应的能力，这些反应不受la类分子的限制，但涉及Ib类分子。我们的系统模拟了肿瘤的反应，这些肿瘤降低了它们的等级，从而逃避了免疫系统的监视。这也使我们能够研究hsp和Ib类分子之间的关系，Ib类分子被认为是细胞内应激和恶性肿瘤的指标。提出了四个具体目标：

DESCRIPTION (provided by applicant): The unique ability of the heat shock proteins (hsps) gp96 and hsp70 to evoke potent anti-tumor immunity appears to rely on two main properties: (1) their peptide-dependent capacity to chaperone and elicit adaptive CTL responses against antigenic peptides through receptor-mediated endocytosis by APCs and representation by APC's MHC classical class la molecules and (2) their peptide-independent capacity to activate APCs. Anti-tumor CTLs are thought to be the main effectors in hsp-mediated responses. However, increasing evidence suggests that NK cells and other less well-characterized cytotoxic cell types recognizing non-classical class Ib molecules may also play a critical role. Since tumors commonly down-regulate expression of MHC class la, thereby escaping immune surveillance, our observation that these hsps can generate anti-tumor immune responses that are not class la-restricted, but possibly involve class Ib molecules, clearly merits further exploration. Therefore, we propose to test the hypothesis that hsps can stimulate classical class la unrestricted CTLs (CCU-CTLs) whose effector function involves class Ib molecules. To this end, we have developed in the frog, Xenopus, a unique and versatile experimental model system characterized by minor and major histocompatibility-defined cloned animals and a MHC class la-negative transplantable thymic lymphoma. This model will be used to evaluate, by in vitro killing assays and by in vivo adoptive cell transfer and antibody depletion protocols, the ability of gp96 and hsp70 to generate anti-tumor peptide-dependent CTL effector responses that are not restricted by class la molecules but involve class Ib molecules. Our system models responses against tumors that have down-regulated their class la thereby escaping immune surveillance. It also allows us to study the relationship between hsp and class Ib molecules that are postulated to act as indicators of intracellular stress and malignancy. Four specific aims are proposed: Aim 1. What are the functional characteristics of the anti-tumor CCU-CTLs? Aim 2. Do hsp70 and gp96 generate similar anti-tumor CCU-CTL effectors? Aim 3. How important is the hsp-generated CCU-CTL responses in tumor immunity in vivo? Aim 4. Do CCU-CTLs interact with class Ib molecules?