Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
J Immunol. 2011 Sep 1;187(5):2824-33. doi: 10.4049/jimmunol.1100852. Epub 2011 Aug 5.
T cells recognizing tumor-associated Ags such as Wilms tumor protein (WT1) are thought to exert potent antitumor reactivity. However, no consistent high-avidity T cell responses have been demonstrated in vaccination studies with WT1 as target in cancer immunotherapy. The aim of this study was to investigate the possible role of negative thymic selection on the avidity and specificity of T cells directed against self-antigens. T cell clones directed against the HLA-A0201-binding WT1(126-134) peptide were generated from both HLA-A02-positive (self-HLA-restricted) and HLA-A02-negative [nonself (allogeneic) HLA [allo-HLA]-restricted] individuals by direct ex vivo isolation using tetramers or after in vitro priming and selection. The functional avidity and specificity of these T cell clones was analyzed in-depth. Self-HLA-restricted WT1-specific clones only recognized WT1(126-134) with low avidities. In contrast, allo-HLA-restricted WT1 clones exhibited profound functional reactivity against a multitude of HLA-A02-positive targets, even in the absence of exogenously loaded WT1 peptide, indicative of Ag-binding promiscuity. To characterize this potential promiscuity, reactivity of the T cell clones against 400 randomly selected HLA-A0201-binding peptides was investigated. The self-HLA-restricted WT1-specific T cell clones only recognized the WT1 peptide. In contrast, the allo-HLA-restricted WT1-reactive clones recognized besides WT1 various other HLA-A0201-binding peptides. In conclusion, allogeneic HLA-A*02-restricted WT1-specific T cells isolated from mismatched donors may be more tumor-reactive than their autologous counterparts but can show specific off-target promiscuity of potential clinical importance. As a result of this, administration of WT1-specific T cells generated from HLA-mismatched donors should be performed with appropriate precautions against potential off-target effects.
T 细胞识别肿瘤相关抗原，如 Wilms 瘤蛋白（WT1），被认为具有强大的抗肿瘤反应性。然而，在以 WT1 为靶点的癌症免疫治疗的疫苗研究中，尚未证实一致的高亲和力 T 细胞反应。本研究旨在探讨负性胸腺选择对针对自身抗原的 T 细胞的亲和力和特异性的可能作用。通过直接使用四聚体从 HLA-A02 阳性（自身 HLA 限制）和 HLA-A02 阴性（非自身（同种异体）HLA [allo-HLA]限制）个体中体外分离，或在体外初始和选择后，从 HLA-A02 阳性个体中生成针对 HLA-A02 结合的 WT1（126-134）肽的 T 细胞克隆。深入分析了这些 T 细胞克隆的功能亲和力和特异性。自身 HLA 限制的 WT1 特异性克隆仅以低亲和力识别 WT1（126-134）。相比之下，allo-HLA 限制的 WT1 克隆对多种 HLA-A02 阳性靶标表现出深刻的功能反应性，即使在没有外源性加载 WT1 肽的情况下，提示抗原结合的混杂性。为了表征这种潜在的混杂性，研究了 T 细胞克隆对 400 个随机选择的 HLA-A0201 结合肽的反应性。自身 HLA 限制的 WT1 特异性 T 细胞克隆仅识别 WT1 肽。相比之下，allo-HLA 限制的 WT1 反应性克隆除了识别 WT1 外，还识别各种其他 HLA-A0201 结合肽。总之，从错配供体中分离的同种异体 HLA-A02 限制的 WT1 特异性 T 细胞可能比其自身对应物更具肿瘤反应性，但可能表现出潜在临床重要性的特定脱靶混杂性。因此，应谨慎使用从 HLA 错配供体中生成的 WT1 特异性 T 细胞进行给药，以防止潜在的脱靶效应。
