Ultralong CDR3 antibodies targeting exhausted T cells

摘要 T细胞耗竭阻止了针对许多肿瘤和慢性感染性疾病的有效免疫应答。 疾病称为“检查点抑制剂”的几种抗体药物靶向受体（例如PD-1，PD-L1， CTLA 4）作用于耗尽的T细胞，并可逆转其表型，导致再活化和免疫应答的能力。 发挥杀伤细胞的功能虽然分子如PD-1、PD-L1、LAG-3、Tim-3、TIGIT和ICOS 已经被描述为耗尽的T细胞的标志物，细胞表面表型不足以 因此，更多的标记物和可能的药物靶点可能存在于耗尽的T细胞表面。 分化簇（或“CD”）分子传统上是基于以下的反应性来定义的： 白细胞表面的单克隆抗体。这些抗体通过以下方法鉴定： 用白色血细胞制剂免疫啮齿动物。最近已经清楚地表明， 不同物种的抗体库在它们的结构方面是显著不同的。 多样性特别地，奶牛具有以下重链互补决定区（CDR H3）： 长达70个氨基酸，由新的带状“茎”和二硫键连接的“节”小 域结构。这与啮齿类动物形成对比，在啮齿类动物中，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）组成的平坦结合表面 CDR H3环。牛抗体具有结合对其他免疫原相对难治的表位的能力。 物种的剧目，并提供了一个新的机会，以进一步确定耗尽的T细胞表面。 为此，我们将用耗尽的T细胞免疫牛，并确定独特的抗体：抗原对 并通过体外和体内逆转耗尽的抗体来证明抗体的功能活性。 T细胞表型。这项研究的抗体可以作为癌症的实验性治疗方法 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.