从噬菌体抗体库中筛选血管内皮细胞新型嘌呤受体功能抗体的研究

The functional binding antibodies to novel purinoceptor selected from phage display library

目的筛选鉴定血管内皮细胞新型嘌呤受体功能性抗体,为进一步研究新型嘌呤受体提供标志物。方法大鼠血管内皮细胞蛋白质免疫BALB/c小鼠,采用噬菌体抗体库技术构建小鼠抗大鼠血管内皮细胞的单链噬菌体抗体库。利用新型嘌呤受体在主动脉内皮细胞表达而在血管平滑肌细胞不表达的特点,先用主动脉内皮细胞进行阳性筛选,再用血管平滑肌细胞进行阴性筛选,从噬菌体抗体库中富集主动脉内皮细胞特异抗体。对筛选到的抗体经可溶性表达后,采用离体血管环功能试验,筛选新型嘌呤受体特异单链抗体。采用免疫组化实验对筛选到的抗体进行鉴定。结果经过4次免疫后,小鼠血清抗内皮细胞蛋白的IgG效价为1∶16000,通过噬菌体表面呈现,得到小鼠抗大鼠内皮细胞免疫噬菌体抗体库容量为8×106。4轮主动脉内皮细胞阳性筛选及大鼠血管平滑肌细胞阴性筛选富集到约2500株主动脉内皮细胞特异抗体,可溶性表达后,在离体血管环上,经过4轮的逐级淘筛得到一株影响腺苷诱发NO依赖性血管收缩反应的功能性抗体ScFv-B,其抑制率为83.4%±21.6%。免疫组化鉴定此抗体与内皮细胞特异结合,功能性鉴定此抗体对腺苷诱发的肠肌收缩反应无影响,初步认为此抗体是新型嘌呤受体特异性功能抗体。结论本研究通过噬菌体抗体库的构建及抗体筛选和鉴定,得到了新型嘌呤受体特异性功能抗体ScFv-B,为进一步采用表达文库筛选的方法克隆新型嘌呤受体基因提供了良好的工具。

Aim To screen antibodies of novel purinoceptor as a marker for further study of the purinoceptor. Method BALB/c mice were immunized for 4 times with rat aortic endothelial cell. Then the phage display system was used to construct a single-chain Fv fragment （ScFv） cDNA library from the total RNA of immunized mice. The characteristics of novel purinoceptor not existing on vascular smooth muscle cell but on aortic endothelium were used to enrich the aortic endothelium specific antibodies. Induced with IPTG, these antibodies were secreted into the periplasm of E. coli. The functional experiment of novel purinoceptor named organ bath experiment was used to screen out the positive ScFv from the soluble expressed antibodies. Immunohistochemistry experiment was used for positive ScFv identification. Results The total mouse anti-rat endothelium lgG is 1 ： 16 000. 8 × 10^6 mouse anti -rat endothelium ScFv cDNA library was successfully constructed. After 4 times of rat endothelium and rat smooth muscle cells screening, 2 500 ScFv eDNA binding membrane of aortic endothelium was enriched. After 4 times of functional screening, a phage-ScFv named B inhibiting the adenosine induced NO dependent construction by 83.4% ±21.6% was selected from the expressed antibodies. Immunohistochemistry experiment showed that ScFv-B combined with aortic endothelium specifically and functional experiment showed that ScFv-B did not have any effect on adenosine induced ileum contraction, indicating that ScFv-B specifically binding to the novel purinoceptor. Conclusions ScFv-B binding specifically to the novel purinoceptor was selected by phage display technique and functional screening experiment which provide a good marker for further study of the novel purinoceptor.