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

The variable domain of heavy chain (V-H) and light chain (V-L) genes of ant i-CD20 monoclonal antibody HI47 were cloned from anti-CD20 ScFv expression vector pCANBTEcd20 by PCR and ligated into vector pYZF to construct chimeri c anti-CD20 Fab' fragment expression vector pYZFcd20. Chimeric anti-CD20 Fa b' fragment was expressed in E. coli 16C9 and purified by protein G affinit y chromatography. Competitive inhibition assay showed that anti-CD20 Fab' f ragment inhibited binding of HI47 to CD20 on the surface of Daudi cells. Re sults from MTT assay indicated that chimeric anti-CD20 Fab' fragment inhibi ted the proliferation of Daudi cells, IC50 = 69 mug/mL. Affinity of chimeri c anti-CD20 Fab' fragment was determined, K-a was about 8.9x10(8) (mol/L)(- 1).