Does interaction of monoclonal antibody charge variants with VEGF-A and ELISA reagents affect its quantification?

The ability of an enzyme linked immunosorbent assay (ELISA) to measure the concentration of charge variants of a monoclonal antibody (mAb) biotherapeutic has been investigated. Percentage recovery was found to be in the range of 80%-120% with inter and intra assay variation between 5% and 15%. Linear regression analysis of ELISA output at different dilutions yielded a good fit (R > 0.98). Assay output was not hindered by the presence of serum proteins and other analytes such as GCSF, demonstrating acceptable precision and specificity. It was concluded that the charge variants of the mAb can be accurately quantified by ELISA.