VEGF DNA疫苗注射部位对小鼠抗原表达与Th细胞活性的影响

Effect of VEGF DNA vaccine on antigen expression and Th cell activities by subcutaneous injection at different sites in mouse

目的探讨小鼠不同部位皮下注射VEGF DNA疫苗对抗原表达与Th细胞活性的影响,为DNA疫苗在体内获得良好的细胞免疫提供优化条件。方法用RT-PCR法从A459细胞株中扩增570 bp的VEGF片段,此片段构建成真核表达重组质粒pVAX1-VEGF;在小鼠耳廓、胸部、腹部及背部皮下注射1μg/μl的pVAX1-VEGF DNA100μl,ELISA法检测血清中VEGF抗原表达水平和脾细胞产生的IL-4及IFN-γ动态变化。结果小鼠耳廓、胸部及腹部免疫,VEGF抗原表达较强,其中耳廓免疫所激活的Th1细胞最强,产生524.2 pg/ml IFN-γ,与胸部、腹部及背部免疫的效果相比,差异显著;pVAX1-VEGF疫苗组与pVAX1对照组的Th1与Th2细胞活性差异均显著,不同部位的pVAX1-VEGF疫苗组对Th2细胞活性无明显影响。结论本研究所构建人源VEGF的DNA疫苗能在小鼠体内有效表达,且不同部位皮下免疫后均可激活Th细胞,但以Th1细胞效应为主和耳廓皮下接种最佳。

Objective To study the effects of VEGF DNA vaccine on antigen expression and Th cell activities by subcutaneous injections at different sites in mouse and to obtain the optimal immune response for DNA vaccine. Methods VEGF gene 570 bp was cloned from human lung cancer cell line A549 by RT-PCR to construct the recombinant eukaryotic expression plasmid pVAX1-VEGF. 100 μl （1 μg/μl）naked DNA vaccine pVAX1-VEGF was injected subcutaneously at ear pinna, chest, abdomen and back skin, respectively. The serum VEGF antigen and cytokines released from splenocytes including IL-4 and IFN-γ were detected by ELISA. Results There was higher VEGF level in serum from ear pinna, chest and abdomen immunized by pVAX1-VEGF, but ear pinna was the best site for inducing stronger Th cell activities to obtain 524.2 pg/ml IFN-γ secreted by splenic lymphocytes. Compared with immune sites at skin chest, abdomen and back, there had statistically significant difference at ear pinna site. There was remarkable effect on Thl and Th2 cell activities between mice immunized by pVAX1-VEGF and pVAX1. But there was no effect of pVAX1-VEGF vaccine on Th2 cell activities at different sites vaccinated in mouse. Conclusion VEGF was effectively expressed in mouse immunized by pVAX1-VEGF DNA vaccine to induce Th cell immunity response. But Th2 cell immunity response was predominant in serum of mouse induced by DNA vaccine;the ear pinna was the best immunization site for it.