Applications of single chain MHC-1 molecules

描述(申请人提供)：MHC I类分子呈递多肽给CD8+细胞溶解T淋巴细胞，具有出色的特异性，从而确保准确识别病毒感染和肿瘤细胞。然而，I类分子的一些功能受到从重链上解离的多肽和/或β2m的限制。事实上，用多肽和/或β2m阻断I类重链组装是肿瘤和病毒逃避CD8+T细胞检测的主要途径。为了克服由于I类分子易拆解而造成的限制，我们将I类分子设计成单链三聚体(SCTS)，其组成为多肽-间隔物-β2M-间隔物-重链。我们最近发表的研究结果表明，SCT具有显著的特性，包括在细胞表面的非凡稳定性，以及对I类/多肽特异性T细胞和抗体的有效刺激。在这笔赠款中，我们将确定SCT是有效的免疫刺激器的机制，并测试它们在基于DC的免疫疗法中以及用作针对肿瘤或病毒的DNA疫苗时相对于天然I类分子的独特优势。具有特别重要意义的是，这些发现将确定SCT在DNA疫苗接种后是通过交叉启动还是直接向CD8+T细胞提呈抗原。此外，我们将测试SCT在体外扩增CD8+T细胞的强烈能力是否源于与抑制性受体的相互作用受损和/或对共刺激的依赖性减少。此外，我们将利用SCT的独特能力来诱导MHC限制性抗体，以将mAb提升为与疾病相关的I类/多肽复合体。这种单抗对于量化疾病进展过程中特定的I类/多肽复合体的表达以及确定这与CD8+T细胞对病毒和肿瘤的激活和效应功能的关系将是非常有价值的。

DESCRIPTION (provided by applicant): MHC class I molecules present peptide to CD8+ cytolytic T lymphocytes with brilliant specificity, thus ensuring accurate identification of virus-infected and tumor cells. However, several of the functions of class I molecules are limited by peptide and/or beta2m dissociation from the heavy chain. Indeed blocking class I heavy chain assembly with peptide and/or beta2m are major pathways used by tumors and viruses to evade detection by CD8+ T cells. To circumvent limitation of class I as a consequence of their propensity to disassemble, we have engineered class I molecules as single chain trimers (SCTs) with the composition of peptide--spacer--beta2m--spacer--heavy chain. Our recently published findings have shown that SCT have remarkable properties including extraordinary stability at the cell surface and potent stimulation of class I/peptide-specific T cells and antibodies. In this grant we will define the mechanisms by which SCT are potent immune stimulators and test their unique advantages over native class I molecules in DC based immunotherapies and when used as DNA vaccines against tumors or viruses. Of particular significance, these findings will determine whether SCT present antigen following DNA vaccination by cross priming or direct presentation to CD8+ T cells. Furthermore we will test whether the keen ability of SCT to expand CD8+ T cells ex vivo results from impaired interactions with inhibitory receptors and/or less dependency on costimulation. In addition we will exploit the unique ability of SCT to elicit MHC-restricted antibodies to raise mAbs to disease-relevant class I/peptide complexes. Such mAb will be invaluable for quantifying expression of specific class I/peptide complexes during disease progression and determine how this correlates with the activation and effector function of CD8+ T cells against viruses and tumors.