Kinetics of antibody binding to surface-immobilized antigen. Analysis of data and an empiric model.

The kinetics of the reaction between monoclonal antibodies and surface-immobilized hapten (dinitrophenyl, DNP) was measured with in situ ellipsometry. A flow cuvette with a small volume (50 microliters) and a high flow rate (3 ml/min) was used in order to avoid mass-transport limitation of the reaction. An initial linear phase was recorded by off-null ellipsometry with a time resolution of 0.1 s. The linear phase was followed by an accelerated rate of antibody binding. The time dependence of the rapid reaction exhibited an exponential form. The apparent rate of antibody binding then decreased continuously with time and the surface concentration of bound antibodies was proportional to the logarithm of time. An empiric model is suggested that describes the time course and the concentration-dependence of the reaction.