Establishment of reverse direct ELISA and its application in screening high-affinity monoclonal antibodies.

Traditionally monoclonal antibody (MAb) titer is determined by indirect enzyme-linked immunosorbent assay (ELISA), which is primarily used to evaluate the quality of MAbs. In this study, the titer and affinity of a group of MAbs against ovalbumin (OVA) were tested by indirect ELISA and the ELISA method reported previously. Data showed that there may be great differences between the indirect ELISA antibody titer and affinity value of MAbs. For the first time, a simple and effective reverse direct ELISA (RD-ELISA) was established for the detection of high-affinity MAbs. Among the group of MAbs to OVA, a certain proportion of antibodies with high affinity but low indirect ELISA titer do exist and can be clearly and efficiently detected by RD-ELISA. This study demonstrates that RD-ELISA is an effective method for high-affinity MAb screening.