Screening of IL-2Rα mimotope from phage display peptide library

Objective To screen IL-2Rα mimotope that would be useful in making small peptide drugs as immunosuppressant. Me-thods Anti-IL-2Rα monoclonal antibody 5G1 (5G1mAb) was purified from mouse ascites by using ion exchange chromatography method and its speciality was identified by ELISA. A c7c phage display peptide library was biopanned with target molecule of 5G1mAb and the speciality of phage clones was identified. Based on the DNA sequence of positive clones, the cyclic peptide was synthesized and its biological activity was investigated. Results After 5 rounds of screening, 5 phage clones which could highly react with 5G1 were identified as the positive clones and the conservative sequence (Lys-X-{X}-Lys-Gly) was obtained. The cyclic peptide was synthesized and named CP,which had immonosupperesive activity comfirmed by the lymphocyte proliferation experiment. Conclusion CP is the mimotope of IL-2Rα and it can be made as an immunosuppressant.