Correlation between the avidity of mouse-human chimeric IgG subclass monoclonal antibodies measured by solid-phase elution ELISA and biospecific interaction analysis (BIA).

In order to validate a simple solid phase assay designed to measure antibody avidity, the avidities of chimeric mouse-human monoclonal antibodies specific for the hapten 4-hydroxy-3-nitrophenyl (NIP) were measured by a thiocyanate elution based ELISA method and compared to the binding kinetics as measured by biospecific interaction analysis (BIA). Despite possessing identical variable regions, the IgG2, IgG3 and IgG4 antibodies differed in their binding characteristics as measured by both techniques. Thiocyanate elution ELISA ranked the antibody avidity in the order IgG4 > IgG2 > IgG3. Biospecific interaction analysis permitted the determination of association and dissociation constants for the three chimeric antibodies. When compared, the affinity constants (K) of the three antibodies ranked in the following order; IgG4 > IgG2 > IgG3. The good agreement between the elution ELISA and BIA avidity ranking suggests that the simple ELISA method reflects the antibody binding characteristics for the three monoclonal antibodies investigated and thus may provide a simple technique to rank antibody avidity.