Butterfield L H, Koh A, Meng W, Vollmer C M, Ribas A, Dissette V, Lee E, Glaspy J A, McBride W H, Economou J S
Division of Surgical Oncology, University of California Los Angeles Medical Center, University of California Los Angeles, 90095-1782, USA.
Cancer Res. 1999 Jul 1;59(13):3134-42.
Alpha-fetoprotein (AFP) is often derepressed in human hepatocellular carcinoma. Peptide fragments of AFP presented in the context of major histocompatibility molecules could serve as potential recognition targets by CD8 T cells, provided these lymphocytes were not clonally deleted in ontogeny. We therefore wished to determine whether the human T-cell repertoire could recognize AFP-derived peptide epitopes in the context of a common class I allele, HLA-A2.1. Dendritic cells genetically engineered to express AFP were capable of generating AFP-specific T-cell responses in autologous human lymphocyte cultures and in HLA-A2.1/Kb transgenic mice. These T cells recognize a 9-mer peptide derived from the AFP protein hAFP(542-550) (GVALQTMKQ). Identified as a potential A2.1-restricted peptide epitope from a computer analysis of the AFP sequence, hAFP(542-550) proved to have low binding affinity to A2.1, but slow off-kinetics. AFP-specific CTL- and IFN-gamma-producing cells recognize hAFP(542-550)-pulsed targets. Conversely, hAFP(542-550) peptide-generated T cells from both human lymphocyte cultures and A2.1/Kb transgenic mice recognized AFP-transfected targets in both cytotoxicity assays and cytokine release assays. These lines of evidence clearly demonstrate that AFP-reactive clones have not been deleted from the human T-cell repertoire and identify one immunodominant A2.1-restricted epitope. These findings also clearly establish AFP as a potential target for T-cell-based immunotherapy.
甲胎蛋白（AFP）在人类肝细胞癌中常出现去抑制现象。在主要组织相容性分子背景下呈现的AFP肽片段可作为CD8 T细胞的潜在识别靶点，前提是这些淋巴细胞在个体发育过程中未发生克隆性缺失。因此，我们希望确定人类T细胞库是否能在常见的I类等位基因HLA - A2.1背景下识别AFP衍生的肽表位。经基因工程改造以表达AFP的树突状细胞能够在自体人类淋巴细胞培养物以及HLA - A2.1/Kb转基因小鼠中产生AFP特异性T细胞反应。这些T细胞识别源自AFP蛋白hAFP(542 - 550)（GVALQTMKQ）的一个9聚体肽。通过对AFP序列的计算机分析确定为潜在的A2.1限制性肽表位，hAFP(542 - 550)被证明与A2.1的结合亲和力较低，但解离动力学缓慢。AFP特异性CTL和产生IFN - γ的细胞识别hAFP(542 - 550)脉冲处理的靶细胞。相反，来自人类淋巴细胞培养物和A2.1/Kb转基因小鼠的hAFP(542 - 550)肽产生的T细胞在细胞毒性测定和细胞因子释放测定中均识别AFP转染的靶细胞。这些证据清楚地表明，AFP反应性克隆并未从人类T细胞库中缺失，并确定了一个免疫显性的A2.1限制性表位。这些发现也明确将AFP确立为基于T细胞的免疫疗法的潜在靶点。
