甲胎蛋白与热休克蛋白70融合DNA疫苗抗肿瘤免疫

目的通过小鼠甲胎蛋白(AFP)与结核分枝杆菌热休克蛋白70(HSP70)基因融合制备DNA疫苗,研究该种DNA疫苗诱导小鼠的免疫应答及其对荷瘤小鼠的治疗作用。方法应用分子克隆技术构建AFP与HSP70的融合表达载体,免疫实验共分5组:磷酸盐缓冲液组、pcDNA3．1组、pcDNA3.1-AFP组、pcDNA3．1-HSP70组、pcDNA3．1- AFP-HSP70组(融合疫苗组),每组7只小鼠。2次免疫后分离小鼠脾细胞,体外诱导细胞毒性T淋巴细胞做杀伤实验, 以乳酸脱氢酶法检测杀伤率,以酶联免疫吸附法检测脾细胞释放的干扰素γ;体外培养小鼠肝癌细胞系Hepa1-6,以每200 μl 4×106细胞数在C57BL／6J小鼠右前腋皮下注射作荷瘤鼠模型,以融合疫苗免疫荷瘤鼠,观测肿瘤大小评价融合疫苗的治疗作用。结果AFP与HSP70的融合疫苗能诱导AFP特异性细胞毒性T淋巴细胞反应,HSP70对于该反应有增强作用(P<0．05),杀伤率在效:靶比为50:1时为32％左右;免疫后小鼠脾细胞体外刺激后分泌干扰素γ约200 pg／ml,融合疫苗组分泌高于其他组(P<0．05),融合疫苗组肿瘤小于其他组(P<0．05),生存时间长于其他组(P<0．05)。结论 AFP与HSP70的融合疫苗能激发AFP特异性细胞毒性T淋巴细胞．并且对肝癌移植瘤有治疗作用。

Immunotherapy with a chimeric AFP and HSP70 gene DNA vaccine targeting on a murine hepatocellular carcinoma

OBJECTIVES: To investigate immune responses and the anti-tumor effect of a constructed Chimeric AFP-Mt.HSP70 DNA vaccine in mice. METHODS: Chimeric AFP-Mt.HSP70 was constructed by molecular clone techniques. Spleen cells derived from mice immunized twice were induced to secrete IFN gamma and were assayed using ELISA. The activity of the cytotoxic lymphocytes (CTL) derived from spleen cells was assayed using lactate dehydrogenase (LDH). 4 x 10(6) Hepa1-6 cells/200 microl were injected subcutaneously into the right axilla of each mouse bearing the tumor. The anti-tumor effect of the recombinant DNA vaccine was evaluated by measuring tumor sizes of the mice. RESULTS: AFP-specific CTL reaction was induced by our chimeric DNA vaccine and Mt.HSP70 enhanced this effect (P < 0.05). The CTL activity was about 32% at E/T=50:1. The IFN gamma secreted by spleen cells of mice immunized with chimeric plasmids was about 200 pg/ml. It was higher than those in the other groups; Tumor sizes of mice immunized with fused plasmids were smaller than those in the other groups. Survival times of mice immunized with the fused plasmids were prolonged. CONCLUSION: Chimeric DNA vaccine can induce AFP-specific CTL reaction and has an anti-tumor effect on transplanted tumors in our murine experiment.