Generation of humanized single chain anti-CD20antibody marker in E.coli

Abstract

Background and Objectives: Rituximab is an anti-CD20 chimeric monoclonal antibody widely used for the treatment of malignant B cells lymphoma. However, the immunogenicity of murine-derived monoclonal antibodies and the large size of full length antibodies restrict cancer immunotherapy. Humanized single chain antibodies can be a solution and a promising alternative for application in immunotherapy. The aim of this study was to produce a humanized SCFV antibody for a potential use in the diagnosis and treatment of B cell lymphoma. Materials and Methods: We used a CDR grafting based approach to design a humanized SCFV gene fragment. The CDRs were grafted onto the closest human frameworks. The designed sequence was expressed in E.coli then purified. The level of expression was analyzed by SDS-PAGE and the reactivity to CD20 expressing cell line was explored by immunoblotting. Results: Similarity analyses revealed that human germline gene IGHV1-46*03 and IGKV1-39*01 have the highest homology with their murine counterparts. Analysis by SDS-PAGE exhibited a high expression level in E. coli. Reactivity to CD20 expressing Raji cells showed that the produced antibody maintained the binding capacity to human CD20 marker. Conclusion: In our study, humanized anti- CD20 SCFV indicated an original antigen-binding affinity. The findings serve as a basis for the development of novel therapeutic strategies in the treatment of CD20- expressing cancers.