Xenotransplantation of pig organs into people may help alleviate the critical shortage of donors which faces organ transplantation. Unfortunately, human antibodies vigorously attack pig tissues preventing the clinical application of xenotransplantation. The swine leukocyte antigens (SLA), homologs of human HLA molecules, can be xenoantigens. SLA molecules, encoded by genes in the pig major histocompatibility complex, contribute to protective immune responses in pig. Therefore, simply inactivating them through genome engineering could reduce the ability of the human immune system to surveil transplanted pig organs for infectious disease or the development of neoplasms. A potential solution to this problem is to identify and modify epitopes in SLA proteins to eliminate their contribution to humoral xenoantigenicity while retaining their biosynthetic competence and ability to contribute to protective immunity. We previously showed that class II SLA proteins were recognized as xenoantigens and mutating arginine at position 55 to proline, in an SLA-DQ beta chain, could reduce human antibody binding. Here, we extend these observations by creating several additional point mutants at position 55. Using a panel of monoclonal antibodies specific for class II SLA proteins, we show that these mutants remain biosynthetically competent. Examining antibody binding to these variants shows that point mutagenesis can reduce, eliminate, or increase antibody binding to class II SLA proteins. Individual mutations can have opposite effects on antibody binding when comparing samples from different people. We also performed a preliminary analysis of creating point mutants near to position 55 to demonstrate that manipulating additional residues also affects antibody reactivity.

中文翻译：

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检查表位诱变作为减少和消除人类抗体与II类猪白细胞抗原结合的策略。

将猪器官异种移植到人体内可能有助于缓解面临器官移植的供体的严重短缺。不幸的是，人抗体强烈攻击猪组织，阻止了异种移植的临床应用。人HLA分子的同源物，猪白细胞抗原（SLA）可以是异种抗原。猪主要组织相容性复合物中的基因编码的SLA分子有助于猪的保护性免疫反应。因此，仅通过基因组工程使它们失活可能会降低人类免疫系统对已移植的猪器官进行传染性疾病或肿瘤形成的能力。该问题的潜在解决方案是鉴定和修饰SLA蛋白中的表位，以消除它们对体液异源抗原的贡献，同时保留其生物合成能力和有助于保护性免疫的能力。我们先前显示II类SLA蛋白被识别为异种抗原，并且在SLA-DQβ链中将55位的精氨酸突变为脯氨酸可以减少人抗体的结合。在这里，我们通过在位置55处创建几个额外的点突变体来扩展这些观察结果。使用一组专门针对II类SLA蛋白的单克隆抗体，我们证明了这些突变体仍具有生物合成能力。检查与这些变体结合的抗体表明，诱变可以减少，消除或增加与II类SLA蛋白的抗体结合。比较来自不同人群的样品时，单个突变可能对抗体结合产生相反的影响。我们还对在55位附近产生点突变进行了初步分析，以证明操纵其他残基也会影响抗体反应性。