Applications of single chain MHC-1 molecules

描述（申请人提供）：MHC I类分子对CD8+溶细胞T淋巴细胞呈肽状，特异性强，保证了对病毒感染细胞和肿瘤细胞的准确鉴定。然而，第一类分子的一些功能受到肽和/或β - 2与重链分离的限制。事实上，用肽和/或β - 2m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。为了避免由于ⅰ类分子易于分解而造成的限制，我们将ⅰ类分子设计为单链三聚体（sct），其组成为肽-间隔- β - 2m-间隔-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和对I类/肽特异性T细胞和抗体的有效刺激。在这项资助中，我们将定义SCT作为有效免疫刺激剂的机制，并测试它们在基于DC的免疫疗法中与天然I类分子相比的独特优势，以及当用作肿瘤或病毒的DNA疫苗时。特别重要的是，这些发现将决定SCT是通过交叉引物接种DNA后呈递抗原还是直接呈递CD8+ T细胞。此外，我们将测试SCT在体外扩增CD8+ T细胞的敏锐能力是否源于与抑制受体的相互作用受损和/或对共刺激的依赖减少。此外，我们将利用SCT的独特能力来诱导mhc限制性抗体，以提高对疾病相关的I类/肽复合物的单克隆抗体。这种单抗对于定量疾病进展过程中特定I类/肽复合物的表达以及确定其与CD8+ T细胞对病毒和肿瘤的激活和效应功能之间的关系将是非常宝贵的。

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.