利用噬菌体肽库确定IL-2Rα表位序列

Identification of IL-2Ra epitope sequences by phage peptide library

目的：确定ＩＬ－2Ｒα表位，为研制高效特异性强的小分子肽类免疫抑制剂奠定基础。方法：用抗ＩＬ－２Ｒα单克隆抗体５Ｇ１对噬菌体六肽库进行筛选，选择出与５Ｇ１结合较强的克隆，经ＤＮＡ序列分析，获得保守序列。对合保守序列的克隆进行生物学活性鉴定。结果：选择出３１个与５Ｇ１结合较强的克隆。获得Ｓｅｒ－Ｓｅｒ－Ｐｈｅ和Ｓｅｒ－Ｓｅｒ－Ａｒｇ两种保守序列。生物学活性鉴定表明：含Ｓｅｒ－Ｓｅｒ－Ａｒｇ序列克隆较含Ｓｅｒ－Ｓｅｒ－Ｐｈｅ被抑制效果好。结论：Ｓｅｒ－Ｓｅｒ－Ａｒｇ是ＩＬ－２Ｒα表位的关键序列。以此表位序列合成的小分子肽可作为ＩＬ－２Ｒα的拮抗剂而成为免疫抑制剂。

Objective: TO determine the amino acid sequences Of IL-2R epitope that would be useful in making small peptide drugs asImmunosuppressant. Methods: A mouse monoclonal antibody that is specific for the human IL-2Ra 5G1 (anti Tac antibody) was used to screena random phage peptide library which have 6 amino-acid residues displayed. Phage clones which could highly react with 5G1 was selected. After DNA sequencing, conservative sequences were acquired. The biological activities of Phage clones were studied by sIL-2Ra blocking assay.Results: After 4 round of biopanning 31 phage clones were selected; two kinds of conservative sequence(Ser-Ser-Phe and Ser-Ser-Arg) weredetermined by single-strand dideoxy-sequencing by chine termination method. Ser-Ser-Arg clones were more effective than Ser-Ser-Phe clones.Conclusion:Ser-Ser -Arg seqience is the IL-2R epitope.