Ferment and purification of CD20F(ab')_(2) antibody

The pYZcpp3 was introduced to E. coli 16C9, in which could be expressed at high level. By using optimize the ferment parameters, during high density culture the final cell density OD_(550) reaches 140 (200g wet cell weigh/L). After the CD20F(ab')_(2) antibody was extracted from E. coli and then purified by FPLC. The yield of soluble CD20F(ab')_(2) antibody was 241mg/L and 50% of it is bivalent. The antigen-binding activity of F(ab')_(2) was analysed by FACS using Raji cells as target cells, the result showed that F(ab')_(2) specifically binds to CD 20~(+) cells. The activity of F(ab')_(2) inhibiting the growth of cell Raji in vitro was examined using MTT, which showed that the IC_(50) of CD20 F(ab')_(2) and Fab' were 22.9#mu#g/L and 42.8#mu#g/mL respectively.