Ultralong CDR3 antibodies targeting exhausted T cells

摘要 T细胞耗尽阻碍了对许多肿瘤和慢性感染的有效免疫反应 疾病。几种被称为“检查点抑制剂”靶向受体的抗体药物(例如PD-1，PD-L1， CTLA4)，并可以逆转其表型，导致重新激活和能力 起到杀伤细胞的作用。而分子如PD-1、PD-L1、LAG-3、TIM-3、TIGIT和ICOS 已被描述为耗竭T细胞的标志，但细胞表面表型不够 因此，更多的标志物和可能的药物靶点可能存在于耗尽的T细胞的表面。 传统上，分化(或CD)分子簇的定义是基于 针对白细胞细胞表面的单抗。这些抗体是通过 用白血球制剂免疫啮齿动物。最近变得明显的是， 不同物种的抗体库在结构上有很大的差异 多样性。尤其是奶牛，具有重链互补决定区域(CDR H3s) 长达70个氨基酸的新型带状“茎”和二硫键连接的“旋钮”迷你 域结构。这与啮齿动物形成对比，在啮齿动物中，大多数CD分子的抗体是 发现，其抗体具有由非常短的(10个氨基酸)组成的平面结合表面 CDR H3循环。奶牛抗体能够结合相对难识别的表位。 并提供了一个新的机会来进一步定义耗尽的T细胞表面。 为此，我们将用耗尽的T细胞免疫牛，并鉴定出独特的抗体：抗原对 并通过体外和体内力竭逆转实验证明了抗体的功能活性 T细胞表型。这项研究的抗体可以作为癌症的实验性治疗药物。 或慢性感染、诊断或重要的研究工具，以进一步确定耗尽的T细胞亚群 和分化途径。

Abstract T cell exhaustion prevents effective immune responses against many tumors and chronic infectious diseases. Several antibody drugs termed “checkpoint inhibitors” target receptors (e.g. PD-1, PD-L1, CTLA4) on exhausted T cells and can reverse their phenotype, leading to re-activation and the ability to function as killer cells. While molecules such as PD-1, PD-L1, LAG-3, Tim-3, TIGIT and ICOS have been described as markers of exhausted T cells, the cell surface phenotype is insufficiently defined; thus, more markers and possible drug targets may exist on the surface of exhausted T cells. Cluster of Differentiation (or “CD”) molecules were traditionally defined based on the reactivity of monoclonal antibodies to the cell surface of leukocytes. These antibodies were identified by immunizing rodents with preparations of white blood cells. It has recently become clear that the antibody repertoires of different species are dramatically different with regards to their structural diversity. Cows, in particular, have heavy chain complementarity determining regions (CDR H3s) of up to 70 amino acids in length comprised of novel -ribbon “stalk” and disulfide bonded “knob” mini domain structures. This contrasts with rodents, where antibodies for most CD molecules were discovered, whose antibodies have flat binding surfaces comprised of very short (10 amino acids) CDR H3 loops. Cow antibodies have the ability to bind epitopes that are relatively refractory to other species’ repertoires, and provide a novel opportunity to further define the exhausted T cell surface. To this end, we will immunize cattle with exhausted T cells and identify unique antibody:antigen pairs and demonstrate functional activity of the antibodies by in vitro and in vivo reversal of the exhausted T cell phenotype. Antibodies from this research could serve as experimental therapeutics for cancer or chronic infection, diagnostics, or important research tools to further define exhausted T cell subsets and differentiation pathways.