The affinity of allergen specific IgE and the competition between IgE and IgG for the allergen in Amb a V sensitive individuals

We have calibrated a solid state PAST assay with affinity purified allergen-specific IgE. We then utilized the calibrated assay to measure the average affinity of individual IgE-containing sera in terms of the average association constant (K) for purified allergen Amb a V. The binding data yielded linear reciprocal plots indicating that the range of affinities of the responding crones was narrow. The range of the average association constant for the IgE-Amb a V complex was 0.9-26 x 10¹⁰ M^-1. The average affinity of the corresponding IgG response in the same individual, estimated by inhibition studies of IgE binding, was 10⁷ M^-1 in one case and lower than 10⁶ M^-1 in all the other cases.