Efficacy of anti-CD20 chimeric Fab' fragment on proliferation of B lymphoma cells

The variable domain of heavy chain (VH) and light chain (VL) genes of anti-CD20 monoclonal antibody HL47 were cloned from anti-CD20 ScFv expression vector pCANBTEcd20 by PCR and ligated into vector pYZF to construct chimeric anti-CD20 Fab’ fragment expression vector pTZFcd20. Chimeric anti-CD20 Fab’ fragment was expressed in E. coli 16C9 and purified by protein G affinity chromatography. Competitive inhibition assay showed that anti-CD20 Fab’ fragment inhibited binding of HI47 to CD20 on the surface of Daudi cells. Results from MTT assay indicated that chimeric anti-CD20 Fab’fragment inhibited the proliferation of Daudi cells, IC50=69 ug/mL. Affinity of chimeric anti-CD20 Fab’ fragment was determined, Ka was about 8.9×108 (mol/L)-1.