ABSTRACT
An enzyme linked immunosorbent assay ( ELISA ) and a flow cytometry assay ( FCA ) based on Wil2-S cells were developed and systematically compared for quantification of recombinant anti-CD20 humanized monoclonal antibody ( rh-anti-CD20zumab) in biological matrix. The specificity, precision and accuracy of each method at correspondingly different linear range showed good results. For ELISA, the precisions of intra-day and inter-day were both <19 . 5%, the relative error was from-18 . 2% to 17 . 6%;For FCA, the precisions of intra-day and inter-day were both <19. 0%, the relative error was from -18. 9% to 18. 4%. The sensitivity of ELISA was significantly higher than that of FCA. The quantitative ranges of ELISA and FCA methods were 0. 04-5. 0 mg/L and 3. 1-200 mg/L, respectively. The concentrations in serum samples and pharmacokinetics analysis were determined by both of two methods after vein drip administration of rh-anti-CD20zumab in rhesus monkeys. Pharmacokinetics data showed that there was excellent consistency between results obtained by two methods at the given dose. We believe that the novel FCA with high speed and high sensitivity can be used to perform PK and PD study of cell surface antigen-targeted antibody derivatives.