Determination of Antigen Binding Activity of Recombinant Humanized Rabbit Anti-Vascular Endothelial Growth Factor Monoclonal Antibody

Objective To determine the antigen binding activity of recombinant humanized rabbit anti-vascular endothelial growth factor(VEGF) monoclonal antibody(McAb) by direct ELISA.Methods The antigen binding activities of reference and test samples of recombinant humanized rabbit anti-VEGF McAb at various concentrations were determined by direct ELISA using VEGF-Fc as coating antigen,based on which the relative binding activities of test samples were calculated according to the EC50 values of test samples and reference,and the method was analyzed for precision.Results Both the antigen binding activities of reference and test samples of rabbit anti-VEGF McAb showed dose-response relationships and were fitted with four-parameter equation.The relative binding activities of three test samples of bulk McAbs were(90.43 ± 18.74)%,(123.56 ± 18.40)% and(106.83 ± 18.47)%,with a mean of(106.94 ± 16.57)% of those of reference of the same batches,respectively.The variation coefficients of three tests were 20.72%,14.89% and 17.29% respectively.The relative binding activities of three test samples of final products of the same batch were(97.34 ± 18.42)%,(123.30 ± 11.08)% and(93.91 ± 4.57)%,with variation coefficients of 18.93%,8.96% and 4.87%,respectively.Conclusion Direct ELISA showed high precision and was easy to handle,which might be used for routine test for antigen binding activity of recombinant humanized rabbit anti-VEGF McAb.