Avidity ELISA
IgE F127 was coated. Isolated anti-IgE IgG or anti-IgE(PNG) IgG were applied at 2μg/ml and were further serial diluted (1:3). After 1 h incubation, the plates were washed 3x 5min either with 7M urea in PBST (PBS containing 0.05% Tween20) or PBST only. Mouse IgG antibodies were detected using HRP-labeled goat anti-mouse IgG (The Jackson Laboratory). The avidity index (AI) was calculated by AIx = OD (dilution x) + urea/OD (dilution x)–urea.