Biosensor-based characterization of serum antibodies during development of an anti-IgE immunotherapeutic against allergy and asthma.

Antibody responses, induced in Cynomolgus monkey by recombinant IgE-derived immunotherapeutic protein against atopic allergies and asthma, were characterized using label-free, real-time protein interaction analysis. The effects of two different immunotherapeutic proteins were compared. Active concentrations of specific anti-IgE antibodies formed were determined in sera sampled at multiple time points, using conditions of total mass transport limitation that were proved to exist on the sensor surface. These concentrations varied from about 0.4 to 35 microg/ml among the monkeys and throughout the immunization period. Based on these concentrations, the rate and affinity constants for the binding of antibody populations to the antigen could be determined. The apparent equilibrium dissociation constant decreased during the immunization period, for all the monkeys, by a factor between 6 and 50, ending at values from approximately 2 x 10(-9) to approximately 2 x 10(-11) M among the animals. This affinity maturation was attributable to the changes in both rate constants, although the magnitude of the contribution of each constant depended partly on specimen, but primarily on the immunotherapeutic used. The immunotherapeutic proteins examined showed excellent immunogenic properties, providing the basis for a new and effective treatment for allergy and asthma.