Differentiation and function of intratumoral memory-phenotype CD8+ T cells

摘要 虽然大量证据表明，CD8 + TIL与突变或非突变的肿瘤抗原反应， 在抗肿瘤免疫中起重要作用，越来越多的证据表明真正的肿瘤反应性T细胞 在许多人类肿瘤中，CD8+细胞仅占所有TIL的一小部分，这表明大多数CD8 + TIL具有 未定义的特异性。基于这个长期存在的问题，我们研究了一个假设， TIL的一部分可以代表CD8 +"记忆表型" T细胞（CD8-MP细胞），一种独特的细胞群 在未致敏小鼠中包含5 - 10%的CD8 + T细胞的未知抗原特异性，表现出常见的 具有先前抗原经验的标志，并且具有在免疫过程中快速扩增和产生IFN-γ的能力。 免疫反应在初步工作中，我们发现CD8-MP细胞对肿瘤的发生有重要贡献。 免疫浸润癌基因驱动的前列腺肿瘤，并表达高密度的PD-1抑制 受体的鉴于这些独特的见解，我们开始了平行研究，旨在进一步阐明 CD8-MP细胞的基础生物学，使用克隆方法来定义CD8-MP细胞的发育轨迹。 这些细胞。我们的新数据表明，许多CD8-MP克隆的分化是由识别CD8-MP启动的。 胸腺中的自我配体通过一个可重复的，精心策划的过程，挑战目前的想法表明， CD8-MP细胞响应于稳态信号在外周中分化。在目标1中，我们将定义 CD8-MP细胞在抗肿瘤免疫中的功能，检验自身配体识别驱动免疫的假设。 CD8-MP细胞早期进入发展中的肿瘤，并且CD8-MP细胞通过以下方式增强抗肿瘤免疫力： 催化更广泛的免疫细胞浸润。此外，我们将确定新的标记，可用于 鉴定肿瘤内的CD8-MP细胞，从而能够更广泛地研究小鼠癌症中的CD8-MP细胞 模型和人类癌症患者。在目标2中，我们将阐明分子和细胞机制， 直接CD8-MP分化，检验CD8-MP分化为两步过程的假设 由胸腺中经典树突状细胞呈递的自身配体的TCR依赖性识别触发。我们 还将利用独特的T细胞抗原发现测定来鉴定由CD8-MP识别的天然自身肽 细胞，从而开辟了新的调查领域，以前无法进入。最终，定义函数 肿瘤内CD8-MP细胞和小鼠中CD8-MP分化的蓝图有望开辟新的 研究和操纵人类这些细胞的途径。

ABSTRACT While considerable evidence demonstrates that CD8+ TILs reactive to mutated or non-mutated tumor antigens play an important role in anti-tumor immunity, expanding evidence indicates that bona fide tumor-reactive T cells comprise only a minor fraction of all TILs in many human tumors, indicating that most CD8+ TILs have undefined specificity. Based on this long-standing question, we examined the hypothesis that a substantial fraction of TILs may represent CD8+ "memory-phenotype" T cells (CD8-MP cells), a unique population of cells of unknown antigen specificity that comprise 5-10% of CD8+ T cells in unprimed mice, exhibit common hallmarks of prior antigen experience, and have the capacity to rapidly expand and produce IFN-γ during an immune response. In preliminary work, we found that CD8-MP cells make substantial contributions to the immune infiltrate of oncogene-driven prostate tumors, and express high densities of the PD-1 inhibitory receptor. Given these unique insights, we embarked on parallel studies aimed at further elucidating the fundamental biology of CD8-MP cells, using a clonal approach to define the developmental trajectories of these cells. Our new data reveal that the differentiation of many CD8-MP clones is triggered by recognition of self-ligands in the thymus via a reproducible, orchestrated process, challenging current thought suggesting that CD8-MP cells differentiate in the periphery in response to homeostatic signals. In Aim 1, we will define the function of CD8-MP cells in anti-tumor immunity, testing the hypothesis that self-ligand recognition drives the early entry of CD8-MP cells into developing tumors, and that CD8-MP cells enhance anti-tumor immunity by catalyzing broader immune cell infiltration. In addition, we will identify novel markers that can be used to identify intratumoral CD8-MP cells, thereby enabling the broader study of CD8-MP cells in murine cancer models and human cancer patients. In Aim 2, we will elucidate the molecular and cellular mechanisms that direct CD8-MP differentiation, testing the hypothesis that CD8-MP differentiation is a two-step process triggered by TCR-dependent recognition of self-ligands presented by classical dendritic cells in the thymus. We will also utilize a unique T cell antigen discovery assay to identify natural self-peptides recognized by CD8-MP cells, thereby opening new areas of inquiry that were previously inaccessible. Ultimately, defining the function of intratumoral CD8-MP cells and the blueprints of CD8-MP differentiation in mice is expected to open new avenues for the study and manipulation of these cells in humans.