Kinetic Analysis of the Interaction between Recombinant Human FcϵRIα and Serum IgEs from Allergic Patients

Binding of IgE to the high-affinity IgE receptor (FcϵRI) is the essential event for allergic reaction. Although there are many reports on binding kinetics between myeloma IgE and FcϵRI, little is known about the kinetics between heterogeneous polyclonal IgE in the serum and FcϵRIα. To elucidate the binding characteristics of heterogeneous serum IgE, we measured kinetic parameters of binding between IgE from allergic patients and a recombinant ectodomain of the human FcϵRIα subunit by real-time interaction analysis based on surface plasmon resonance. Purified IgE monomer from the plasma of allergic patients displayed kinetics for the interaction with FcϵRIα similar to those of myeloma IgE. In the case of crude IgE samples from allergic patients, one of seven specimens showed significantly higher affinity than highly purified IgE, suggesting that it is possible for IgEs in this specimen to form complexes of higher molecular weight.