Immunoglobulin E (IgE) is one of the members the 5 classes of immunoglobulins (IgM, IgG, IgD, IgA, IgE).It is produced by plasma cells and accounts for less than 0.01% of the total immunoglobulin.IgE has a unique chemical structure and various physiological functions, such as type I hypersensitivity reactions, parasitic infections, autoimmune processes, and venom protection. Besides,IgE binds to Receptor I For The Fc Region Of Immunoglobulin E (FceRI) on mast cells and basophils via its Fc - region, triggering signal transduction, thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human IgE and recombinant human FceRI.Briefly, IgE was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to FceRI-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-IgE pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 µL stop solution to the wells and read at 450/630nm immediately. The binding activity of recombinant human IgE and recombinant human FceRI was shown in Figure 1, the EC50 for this effect is 0.69ug/mL.