The direct alloresponse, pivotal in transplant rejection, occurs when recipient T cells recognize intact allogeneic peptide-major histocompatibility complex (pMHC) complexes. Despite extensive research, our understanding of alloreactive CD8+ T cells against an individual MHC allele in humans remains limited, especially their precursor frequency, MHC specificity, and peptide specificity. By using K562 cell–based artificial antigen-presenting cells expressing human leukocyte antigen (HLA)-A∗01:01, HLA-A∗02:01, or HLA-A∗03:01, we determined that the precursor frequency of alloreactive CD8+ T cells against a single MHC allele ranges from 0.1% to 0.5%. Further, these cells exhibited MHC specificity regarding proliferation, activation, interferon gamma secretion, and cytolytic ability, with limited crossreactivity toward nontargeted MHC alleles. Focusing on anti-A2 alloreactive CD8+ T cells, we developed a peptide-exchangeable artificial antigen-presenting cell that displays selected peptides on HLA-A∗02:01. From a set of 95 computationally curated A2-restricted peptides most abundant in renal tubular cells, we identified 2 immunogenic kidney peptides across multiple donors. Overall, our findings significantly enhance the understanding of direct alloresponse and provide a toolkit for future mechanistic studies and reproducible patient monitoring.

中文翻译：

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主要组织相容性复合物和肽特异性支持 CD8+ T 细胞直接同种异体反应


当受体 T 细胞识别完整的同种异体肽-主要组织相容性复合体 （pMHC） 复合体时，就会发生直接同种异体反应，这在移植排斥反应中起着关键作用。尽管进行了广泛的研究，但我们对人类中针对单个 MHC 等位基因的同种异体反应性 CD8+ T 细胞的了解仍然有限，尤其是它们的前体频率、MHC 特异性和肽特异性。通过使用表达人类白细胞抗原 （HLA）-A∗01：01、HLA-A∗02：01 或 HLA-A∗03：01 的基于 K562 细胞的人工抗原呈递细胞，我们确定针对单个 MHC 等位基因的同种异体反应性 CD8+ T 细胞的前体频率为 0.1% 至 0.5%。此外，这些细胞在增殖、激活、干扰素 γ 分泌和溶细胞能力方面表现出 MHC 特异性，对非靶向 MHC 等位基因的交叉反应性有限。专注于抗 A2 同种异体反应性 CD8+ T 细胞，我们开发了一种可肽交换的人工抗原呈递细胞，可在 HLA-A∗02：01 上显示选定的肽。从一组在肾小管细胞中含量最高的 95 种计算精选的 A2 限制性肽中，我们在多个供体中鉴定了 2 种免疫原性肾肽。总体而言，我们的研究结果显着增强了对直接同种异体反应的理解，并为未来的机制研究和可重复的患者监测提供了工具包。