Quantitation of interaction of anti-metatype monoclonal antibodies specific for the variable regions of a high affinity liganded monoclonal antibody.

Four hamster monoclonal anti-metatype antibodies were characterized in terms of their binding properties with liganded murine monoclonal single-chain antifluorescein antibody 4-4-20. Based on induced delays in the rate of ligand (fluorescein) dissociation upon the binding of each monoclonal anti-Met antibody, apparent Kd values were determined for monoclonal antibodies 3A5-1, P1E11, 4A6, and 2C3 (3.6 x 10(-8), 3.6 x 10(-8), 5.0 x 10(-8), and 2.6 x 10(-7) M, respectively). The interaction of hamster monoclonal antibody 3A5-1 with liganded SCA 4-4-20 and IgG 4-4-20 was also evaluated on the basis of deuterium oxide exchange to assess the relative ability of each antibody to stabilize the intrinsic dynamics of the variable domains of the single-chain molecule. The results indicated a correlation between the apparent Kd of the monoclonal anti-Met antibody and the degree of delay in the rate of ligand dissociation from the primary antibody.