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白介素21是具有免疫调节功能的I型细胞因子,在异常状态下可介导类风湿关节炎、系统性红斑狼疮和炎性肠病等多种自身免疫性疾病。为了拮抗白介素21的生物学活性,采用固相亲和筛选的方法,从Griffin1全人源噬菌体单链抗体库中筛选出抗白介素21的单链抗体。经过4轮亲和筛选,可溶性ELISA结果表明65%的噬菌体克隆可与IL-21发生特异性结合,经基因测序挑选出高亲和力的单链抗体FG8,转化至大肠杆菌HB2151中进行可溶性表达,采用镍柱亲和层析对表达的蛋白进行纯化后,SDS-PAGE和Western blot检测单链抗体相对分子质量为30 k。定量ELISA分析显示,单链抗体FG8与白介素21的结合呈浓度依赖性,可进一步研究用于炎症及自身免疫性疾病的诊断及靶向性治疗。
Interleukin 21 is a type I cytokine with immunomodulatory function and mediates various autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus and inflammatory bowel disease under abnormal conditions. In order to antagonize the biological activity of interleukin 21, a single chain antibody against interleukin 21 was screened from the Griffin 1 whole human phage scFv library by solid phase affinity screening. After 4 rounds of affinity screening, soluble ELISA results showed that 65% of the phage clones could specifically bind to IL-21. The high-affinity single-chain antibody FG8 was selected by gene sequencing and transformed into E. coli HB2151 for soluble expression. Purification of the expressed protein by nickel column affinity chromatography, SDS-PAGE and Western blot detection of single chain antibody relative molecular mass of 30 k. Quantitative ELISA analysis showed that the single chain antibody FG8 and interleukin 21 in a concentration-dependent manner, further research for the diagnosis of inflammation and autoimmune diseases and targeted therapies.