病毒肽/HLA-A2与单链抗体融合蛋白介导病毒特异性CTL杀伤肿瘤细胞

pMHC/scFv fusion protein mediates killing of tumor cells by viral specific cytotoxic T cells

目的 研究人工构建的病毒肽/HLA-A2复合物与抗转铁蛋白受体（CD71）单链抗体融合蛋白（HBC-A2/scFv）介导病毒特异性CTL杀伤肿瘤细胞的作用.方法 将HBC-A2/scFv融合蛋白结合到高表达CD71的肿瘤细胞表面,利用加载HBC抗原肽的 T2细胞在体外诱导产生抗原特异性CTL,用乳酸脱氢酶释放法检测CTL对肿瘤细胞的特异性杀伤作用.结果 HBC-A2/scFv融合蛋白可结合于CD71阳性的肿瘤细胞K562、HepG2及U937表面,结合率分别为：37.30%±8.25%、27.20%±3.88%和21.80%±6.49%.体外诱导产生的CTL/HBC能杀伤结合有HBC-A2/scFv的K562、HepG2及U937细胞,杀伤率明显高于未结合HBC-A2/scFv的对照组（K562：42.08%±1.14%vs 8.07%±1.39% HepG2：49.72%±1.59%vs12.46%±1.26% U937：39.72%±3.26%vs 7.13%±1.48%）.结论 HBC-A2/scFv融合蛋白能介导病毒特异性CTL杀伤肿瘤细胞,为肿瘤细胞免疫治疗提供了新的思路和实验依据.

Objective To study whether the HBC-A2/scFv fusion protein mediates killing of tumor cells by viral specific cytotoxic T cells. Methods The fusion protein was attached to the CD71-expressing, HLA class Ⅰ negative tumor cells. And then, cytolysis by viral peptide-specific CTLs which were generated by co-culture of peripheral blood lymphocytes from HLA-A2 positive donors with inactivated T2 cells pulsed with the viral peptide were tested by lactate dehydrogenase （LDH） releasing. Results The fusion protein can attach the active viral peptide/HLA-A2 complex to K562, HepG2 and U937 cells through binding of CD71 scFv to CD71 （37.30% ±8.25%, 27.20% ±3.88%, 21.80% ±6.49% ） and mediate cytotoxicity of viral peptide-specific CTLs against those cells in vitro （ K562： 42.08% ± 1.14% vs 8.07%± 1.39% HepG2： 49.72% ± 1.59% vs 12.46% ± 1.26% U937： 39.72% ± 3.26% vs 7.13% ±1.48% ）. Conclusion This viral peptide/HLA-A2 complex targeted by CD71 scFv is able to redirect viral peptide-specific T-cell mediated immune responses against tumor cells.