Objective: To construct chimeric antigen receptor (CAR) T cells targeting CD52 (CD52 CAR-T) and validate the effect of CD52 CAR-T cells on CD52-positive leukemia. Methods: A second-generation CD52-targeting CAR bearing 4-1BB costimulatory domain was ligated into a lentiviral vector through molecular cloning. Lentivirus was prepared and packaged by 293 T cells with a four-plasmid system. Fluorescein was used to label cell surface antigens to evaluate the phenotype of CD52 CAR-T cells after infection. Flow cytometry and ELISA were used to evaluate the specific cytotoxicity of CD52 CAR-T cells to CD52-positive cell lines in vitro. Results: ①A pCDH-CD52scFv-CD8α-4-1BB-CD3ζ-GFP expressing plasmid was successfully constructed and used to transduce T cells expressing a novel CD52-targeting CAR. ②On day 6, CD52-positive T cells were almost killed by CD52-targeted CAR-T post lentivirus transduction [CD52 CAR-T (4.48 ± 4.99) %, vs Vector-T (56.58±19.8) %, P=0.011]. ③T cells transduced with the CAR targeting CD52 showed low levels of apoptosis and could be expanded long-term ex vivo. ④The CD52 CAR could promote T cell differentiation into central and effector memory T cells, whereas the proportion of T cells with a CD45RA(+) effector memory phenotype were reduced. ⑤CD52 CAR-T cells could specifically kill CD52-positive HuT78-19t cells but had no killing effect on CD52-negative MOLT4-19t cells. For CD52 CAR-T cells, the percentage of residual of HuT78-19t cells was (2.66±1.60) % at an the E:T ratio of 1∶1 for 24 h, while (56.66±5.74) % of MOLT4-19t cells survived (P<0.001) . ⑥The results of a degranulation experiment confirmed that HuT78-19t cells significantly activated CD52 CAR-T cells but not MOLT4-19t cells[ (57.34±11.25) % vs (13.06± 4.23) %, P<0.001]. ⑦CD52 CAR-T cells released more cytokines when co-cultured with HuT78-19t cells than that of vector-T cells [IFN-γ: (3706±226) pg/ml, P<0.001; TNF-α: (1732±560) pg/ml, P<0.01]. Conclusions: We successfully prepared CD52 CAR-T cells with anti-leukemia effects, which might provide the foundation for further immunotherapy.
目的： 构建一种靶向CD52的嵌合抗原受体T细胞（CD52 CAR-T），探索其对CD52(+)白血病的治疗效果。 方法： 应用分子克隆技术构建以CD52为抗原结合区的CD52 scFv、4-1BB为共刺激分子的二代CAR-T细胞。慢病毒载体包装后感染T细胞，制备CD52 CAR-T细胞，通过流式细胞术检测CD52 CAR-T细胞CD4、CD8细胞亚群及其分化状态。通过体外杀伤实验、脱颗粒实验及细胞因子的释放等功能实验，观察CD52 CAR-T细胞对CD52(+)白血病细胞的特异性细胞毒作用。 结果： ①成功构建了pCDH-CD52 scFv-CD8α-4-1BB-CD3ζ-GFP表达载体，感染人T细胞，获得靶向CD52的CAR-T细胞。②感染CD52 CAR表达载体的第6天，T细胞中表达CD52的细胞可被清除[CD52 CAR-T组CD52(+) T细胞为（4.48±4.99）%，Vector-T组为（56.58±19.8）%，P=0.011]。③CD52 CAR-T的自我杀伤不会影响T细胞的增殖，培养后期CD52 CAR-T组的增殖速度高于Vector-T组。④T细胞表型检测发现CD52 CAR可以促进CAR-T细胞向中心记忆T细胞及效应记忆T细胞分化，减少CAR-T细胞向终末效应细胞分化。⑤CD52 CAR-T细胞与HuT78-19t及MOLT4-19t靶细胞以效靶比1∶1共培养24 h，HuT78-19t细胞可被清除，而对MOLT4-19t细胞无明显杀伤作用[（2.66±1.60）%对（56.66%±5.74）%，P<0.001]。⑥脱颗粒实验显示，HuT78-19t细胞对CD52 CAR-T细胞的激活作用显著高于MOLT4-19t细胞[（57.34±11.25）%对（13.06±4.23）%，P<0.001]。⑦CD52 CAR-T与HuT78-19t细胞共培养48 h上清中细胞因子分泌水平[IFN-γ（3706±226）pg/ml、TNF-α（1732±560）pg/ml]远高于MOLT4-19t细胞组[IFN-γ（1577±846）pg/ml、TNF-α（74±12）pg/ml]（P值均<0.01）。 结论： 该研究成功制备了具有抗白血病作用的CD52 CAR-T细胞，为进一步的靶向CD52的免疫治疗奠定了基础。.
Keywords: CD52; Chimeric antigen receptor T cells; Immunotherapy.