Tsang K Y, Zaremba S, Nieroda C A, Zhu M Z, Hamilton J M, Schlom J
Laboratory of Tumor Immunology and Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
J Natl Cancer Inst. 1995 Jul 5;87(13):982-90. doi: 10.1093/jnci/87.13.982.
The human carcinoembryonic antigen (CEA), which is expressed in several cancer types, is a potential target for specific immunotherapy using recombinant vaccines. Previous studies have shown that when the CEA gene is placed into vaccinia virus, the recombinant vaccine (rV-CEA) can elicit T-cell responses in both rodents and non-human primates.
Our objective was to determine if rVCEA could elicit CEA-specific T-cell responses in humans with appropriate human leukocyte antigen (HLA) motifs.
Peripheral blood lymphocytes (PBLs) obtained from patients with metastatic carcinoma, both before and after vaccination with rV-CEA, were analyzed for T-cell response to specific 9- to 11-mer CEA peptides selected to conform to human HLA class I-A2 motifs.
While little or no T-cell growth was seen from preimmunization PBLs of patients pulsed with CEA peptides and interleukin 2 (IL-2), T-cell lines were obtained from PBLs of patients after vaccination with one to three cycles of stimulation. Cytolytic T-cell lines from three HLA-A2 patients were established with a 9-amino acid peptide (CAP-1), and the CD8+/CD4+ double-positive T-cell line (V24T) was chosen for detailed analysis. When autologous Epstein-Barr virus (EBV)-transformed B cells were either incubated with CAP-1 peptide or transduced with the CEA gene using a retroviral vector, they were lysed by the V24T cell line, but allogeneic non-A2 EBV-transformed B cells were not. The SW403 human colon carcinoma cell line, which is CEA positive and HLA-A2 positive, was also lysed by the V24T cell line, while two non-HLA-A2 CEA-positive colon carcinoma cell lines were not. To further confirm the class I HLA-A2 restricted nature of the V24T cytotoxicity, the non-HLA-A2 SW837 CEA-expressing colon carcinoma cell line was infected with a recombinant vaccinia virus expressing the HLA class I-A2 gene, and it became susceptible to V24T lysis. Cells infected with vector alone were not lysed.
This study demonstrates for the first time (a) the ability to generate a human cytolytic T-cell response to specific epitopes of CEA, (b) the class I HLA-A2 restricted nature of the T-cell mediated lysis, and (c) the ability of human tumor cells to endogenously process CEA to present a specific CEA peptide in the context of major histocompatibility complex for T-cell-mediated lysis.
These findings have implications in the development of specific second-generation cancer immunotherapy protocols.
人癌胚抗原（CEA）在多种癌症类型中表达，是使用重组疫苗进行特异性免疫治疗的潜在靶点。先前的研究表明，当将CEA基因导入痘苗病毒时，重组疫苗（rV-CEA）可在啮齿动物和非人类灵长类动物中引发T细胞反应。
我们的目标是确定rVCEA是否能在具有适当人类白细胞抗原（HLA）基序的人类中引发CEA特异性T细胞反应。
分析了转移性癌患者在接种rV-CEA前后获得的外周血淋巴细胞（PBL）对选定的符合人类HLA I类A2基序的特定9至11肽段的T细胞反应。
用CEA肽段和白细胞介素2（IL-2）刺激的患者免疫前PBL几乎未见T细胞生长或无T细胞生长，而在接种疫苗后经一至三个周期刺激的患者PBL中获得了T细胞系。用一种9氨基酸肽段（CAP-1）建立了来自三名HLA-A2患者的细胞毒性T细胞系，并选择CD8+/CD4+双阳性T细胞系（V24T）进行详细分析。当自体爱泼斯坦-巴尔病毒（EBV）转化的B细胞与CAP-1肽段孵育或用逆转录病毒载体转导CEA基因时，它们被V24T细胞系裂解，但同种异体非A2 EBV转化的B细胞未被裂解。CEA阳性且HLA-A2阳性的SW403人结肠癌细胞系也被V24T细胞系裂解，而两个非HLA-A2 CEA阳性结肠癌细胞系未被裂解。为了进一步证实V24T细胞毒性的I类HLA-A2限制性，用表达HLA I类A2基因的重组痘苗病毒感染非HLA-A2 SW837 CEA表达结肠癌细胞系，它变得易被V24T裂解。仅用载体感染细胞未被裂解。
本研究首次证明了（a）对CEA特定表位产生人细胞毒性T细胞反应的能力，（b）T细胞介导裂解的I类HLA-A2限制性，以及（c）人类肿瘤细胞内源性加工CEA以在主要组织相容性复合体背景下呈递特定CEA肽段以供T细胞介导裂解的能力。
这些发现对特定第二代癌症免疫治疗方案的开发具有重要意义。
