Department of Immunology, Leiden University Medical Center, Leiden, Netherlands.
Department of Internal Medicine (Nephrology), Leiden University Medical Center, Leiden, Netherlands.
Front Immunol. 2022 Jan 28;12:800946. doi: 10.3389/fimmu.2021.800946. eCollection 2021.
Matching strategies based on HLA eplets instead of HLA antigens in solid organ transplantation may not only increase the donor pool for highly sensitized patients, but also decrease the incidence of donor-specific antibody formation. However, since not all eplets are equally capable of inducing an immune response, antibody verification is needed to confirm their ability to be bound by antibodies, such that only clinically relevant eplets are considered. The HLA Epitope Registry has documented all theoretically defined HLA eplets along with their antibody verification status and has been the foundation for many clinical studies investigating eplet mismatch in transplantation. The verification methods for eplets in the Registry range from polyclonal sera from multi- and uni-parous women to murine and human monoclonal antibodies (mAbs), and antibodies purified by adsorption and elution from sera of HLA immunized individuals. The classification of antibody verification based on different methods for validation is problematic, since not all approaches represent the same level of evidence. In this study, we introduce a classification system to evaluate the level of evidence for the antibody-verified status of all eplets in the HLA Epitope Registry. We demonstrate that for a considerable number of eplets, the antibody-verified status is solely based on polyclonal serum reactivity of multiparous women or on reactivity of murine mAbs. Furthermore, we noted that a substantial proportion of patient sera analyses and human mAb data presented in the HLA Epitope Registry Database has never been published in a peer-reviewed journal. Therefore, we tested several unpublished human HLA-specific mAbs by luminex single antigen beads assay to analyze their HLA reactivity for eplet antibody verification. Although the majority of analyzed mAbs indeed verified their assigned eplets, this was not the case for a number of eplets. This comprehensive overview of evidence for antibody verification of eplets in the HLA Epitope Registry is instrumental for future investigations towards eplet immunogenicity and clinical studies considering antibody-verified eplet mismatch in transplantation and warrants further standardization of antibody verification using high quality data.
基于 HLA 表位而不是 HLA 抗原进行实体器官移植的配型策略，不仅可以增加高度致敏患者的供体库，还可以降低供体特异性抗体形成的发生率。然而，由于并非所有表位都具有同等的诱导免疫反应的能力，因此需要进行抗体验证以确认其与抗体结合的能力，只有具有临床相关性的表位才会被考虑。HLA 表位注册库记录了所有理论上定义的 HLA 表位及其抗体验证状态，并且是许多研究移植中表位不匹配的临床研究的基础。注册库中表位的验证方法范围从多产和单产妇女的多克隆血清到鼠和人单克隆抗体（mAbs），以及从 HLA 免疫个体的血清中通过吸附和洗脱纯化的抗体。基于不同验证方法对抗体验证进行分类存在问题，因为并非所有方法都代表相同的证据水平。在这项研究中，我们引入了一种分类系统，用于评估 HLA 表位注册库中所有表位的抗体验证状态的证据水平。我们表明，对于相当数量的表位，抗体验证状态仅基于多产妇女的多克隆血清反应性或鼠 mAb 的反应性。此外，我们注意到，HLA 表位注册库数据库中呈现的大量患者血清分析和人 mAb 数据从未在同行评议的期刊上发表过。因此，我们通过 Luminex 单抗原珠测定法测试了几种未发表的人类 HLA 特异性 mAb，以分析它们用于表位抗体验证的 HLA 反应性。尽管大多数分析的 mAb 确实验证了其指定的表位，但并非所有表位都是如此。这种对 HLA 表位注册库中表位抗体验证证据的全面概述，对于未来对表位免疫原性的研究以及考虑移植中抗体验证的表位不匹配的临床研究具有重要意义，并需要使用高质量的数据进一步标准化抗体验证。
