Dissociation kinetics of antigen-antibody interactions: studies on a panel of anti-albumin monoclonal antibodies

Kinetic parameters and equilibrium association constants (K) are reported for a panel of antibovine serum albumin (BSA) monoclonal antibodies (MAb) immobilized onto agarose particles. For 12 covalently immobilized MAb of moderate affinity (K = 0.25 × 10⁸-1.2 × 10⁸ M^-1) measured dissociation time constants varied two orders of magnitude, from 2.1 to 410 min. Directly measured association rate parameters agree with values calculated from measured equilibrium and dissociation rate parameters. Dissociation time constants and equilibrium association constants were also determined for eight MAb immobilized biospecifically (via their F_c regions). A significantly lower K was observed with those MAb which were covalently immobilized as opposed to biospecifically immobilized. These decreases in K appear to reflect decreased association rates rather than increased dissociation rates. The data suggest that, for the MAb described herein, dissociation rates do not correlate with equilibrium association constants.