Denkberg Galit, Cohen Cyril J, Lev Avital, Chames Patrick, Hoogenboom Hennie R, Reiter Yoram
Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.
Proc Natl Acad Sci U S A. 2002 Jul 9;99(14):9421-6. doi: 10.1073/pnas.132285699. Epub 2002 Jul 1.
Specificity in the cellular immune system is controlled and regulated by the T cell antigen receptor (TCR), which specifically recognizes peptide/major histocompatibility complex (MHC) molecules. In recent years many cancer-associated MHC-restricted peptides have been isolated and because of their highly restricted fine specificity, they are desirable targets for novel approaches in immunotherapy. Antibodies that would recognize tumor-associated MHC-peptide complexes with the same specificity as the TCR would be valuable reagents for studying antigen presentation by tumor cells, for visualizing MHC-peptide complexes on cells, and eventually for monitoring the expression of specific complexes during immunotherapy. To generate molecules with such a unique fine specificity, we selected a large nonimmune repertoire of phage Fab antibodies on recombinant HLA-A2 complexed with three common antigenic T cell, HLA-A2-restricted epitopes derived from the melanoma differentiation antigen gp100. We were able to isolate a surprisingly large panel of human recombinant Fab antibodies that exhibit a characteristic TCR-like binding specificity to each of the three gp100-derived epitopes, yet unlike TCRs, they did so with an affinity in the nanomolar range. These TCR-like antibodies recognize the native MHC-peptide complex expressed on the surface of antigen-presenting cells. Moreover, they can detect the specific MHC-peptide complexes on the surface of melanoma tumor cells. These results demonstrate the ability to isolate high-affinity human recombinant antibodies with the antigen-specific, MHC-restricted specificity of T cells, and this ability was demonstrated for three different epitopes of the same melanoma-derived antigen.
细胞免疫系统的特异性由T细胞抗原受体（TCR）控制和调节，TCR可特异性识别肽/主要组织相容性复合体（MHC）分子。近年来，许多与癌症相关的MHC限制性肽已被分离出来，由于它们具有高度受限的精细特异性，因此是免疫治疗新方法的理想靶点。能够以与TCR相同的特异性识别肿瘤相关MHC-肽复合物的抗体，对于研究肿瘤细胞的抗原呈递、可视化细胞表面的MHC-肽复合物以及最终监测免疫治疗期间特定复合物的表达而言，将是有价值的试剂。为了生成具有这种独特精细特异性的分子，我们在与三种常见抗原性T细胞（源自黑色素瘤分化抗原gp100的HLA-A2限制性表位）复合的重组HLA-A2上，选择了一个大型的非免疫噬菌体Fab抗体文库。我们能够分离出令人惊讶的一大组人重组Fab抗体，它们对三种gp100衍生表位中的每一种都表现出特征性的TCR样结合特异性，但与TCR不同的是，它们以纳摩尔范围内的亲和力做到了这一点。这些TCR样抗体识别抗原呈递细胞表面表达的天然MHC-肽复合物。此外，它们能够检测黑色素瘤肿瘤细胞表面的特异性MHC-肽复合物。这些结果证明了分离具有T细胞抗原特异性、MHC限制性特异性的高亲和力人重组抗体的能力，并且针对同一黑色素瘤衍生抗原的三种不同表位证明了这种能力。
