异位hCGβ基因免疫诱导的特异性抗肿瘤免疫应答

Specific anti-tumor immunity induced by gene immunization with ectopic hCGβ encoding gene

目的 观察异位hCGβ基因免疫诱导的肿瘤特异性免疫应答及其抗肿瘤作用 ,为肿瘤的免疫生物治疗寻求新途径。方法 构建含hCGβ编码基因的质粒TR4 2 1 hCGβ ,对BALB/c小鼠实施基因免疫 ,并以空质粒为对照。采用ELISA法和3 H TdR掺入法分别检测免疫小鼠血清中特异性抗hCGβ IgG抗体及其对肿瘤细胞体外生长的抑制作用 ;特异抗原体外刺激免疫小鼠脾细胞后 ,用3 H TdR掺入法和3 H TdR释放法分别检测其特异性增殖活性和细胞毒活性 ;皮下接种SP2 /0 hCGβ细胞攻击免疫小鼠 ,以成瘤率及实体瘤重量评估体内抗瘤效果。结果 全部TR4 2 1 hCGβ质粒免疫小鼠均产生高水平的抗hCGβ IgG抗体 ,该抗体可抑制肿瘤细胞的体外生长 ,与对照血清相比 ,差异有显著差性 (P <0 .0 5 ) ;hCGβ蛋白、灭活SP2 /0 hCGβ细胞以及两者混合均能刺激TR4 2 1 hCGβ质粒免疫小鼠脾细胞的体外增殖 (SI值分别为 1.5 3、1.81和 2 .0 5 ) ,与空质粒免疫小鼠相比 ,差异有显著性 (P <0 .0 1) ;特异抗原刺激的TR4 2 1 hCGβ质粒免疫小鼠脾细胞对SP2 /0 hCGβ细胞的细胞毒活性明显高于SP2 /0细胞(P <0 .0 1) ;空质粒免疫小鼠接种SP2 /0 hCGβ细胞后成瘤率为 10 0 % ,瘤重达 3.37g ,而TR4 2 1 hCGβ质粒免疫小鼠的成瘤率为 16 .6 6 % 。

Objective To investigate the specific anti tumor immunity induced by gene immunization with ectopic hCG encoding gene. Methods BALB/c mice were immunized with plasmid TR421 hCGβ coding for hCGβ and mock DNA for 3 times at 3 weekly intervals. The level of specific anti hCGβ IgG antibody in the serum was determined by ELISA at the indicated time in the two groups. The growth inhibitory activity of the sera against tumor cells was examined in vitro by Thymidine incorporation assay. Specific lympho proliferation versus hCGβ was detected by Thymidine incorporation assay with hCGβ protein or inactivated SP2/0 hCGβ cells as specific stimulating antigen. Cytotoxic T lymphocyte(CTL) activity of the splenocytes derived from the immunized mice was measured by Thymidine release assay. Protective assay was performed by subcutaneous inoculation of SP2/0 hCGβ cells into the immunized mice. The weight and formation rate of the tumor were evaluated after challenge. Results All mice immunized with plasmid TR421 hCGβ developed high level of anti hCGβ antibodies, which could inhibit the growth of Hela cells and SP2/0 hCGβ cells compared with the serum from animals immunized with mock DNA ( P <0.05). The high level specific lympho proliferation against hCGβ protein or/and inactivated SP2/0 hCGβ cells were shown in TR421 hCGβimmunized mice, whereas no significant proliferative activity was found in mock DNA immunized animals ( P <0.01). A strong cytotoxic activity against SP2/0 hCGβ in TR421 hCGβ immunized mice was found. Inoculation of SP2/0 hCGβ cells into the mice immunized with mock DNA developed large tumors within 25 days. But a marked reduction of tumor weight and formation rate was found after the tumor cells challenge in the mice immunized with TR421 hCGβ plasmid DNA ( P <0.01). Conclusion The gene immunization of ectopic hCGβ encoding gene, eliciting high level of specific humoral and cellular immune responses, could inhibit the growth of tumor cells harboring ectopic hCGβ in vitro and in vivo. [