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IgE binds asymmetrically to its B cell receptor CD23.
Balvinder Dhaliwal1, Marie O Y Pang2,3, Anthony H Keeble2,3
1Division of Infection, Immunity and Respiratory Medicine, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Sciences Centre and Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN, U.K.
Scientific Reports
|April 1, 2017
Summary
The study reveals how CD23 receptors bind to immunoglobulin E (IgE) antibodies, crucial for allergic responses. Understanding these interactions offers new avenues for developing therapies targeting allergic diseases.
Area of Science:
- Immunology
- Structural Biology
- Allergy Research
Background:
- Immunoglobulin E (IgE) is central to allergic disease mechanisms.
- IgE effector functions are mediated by interactions with FcεRI and CD23 receptors.
- FcεRI interaction drives allergic sensitization and inflammation, while CD23 binding regulates IgE synthesis and transcytosis.
Purpose of the Study:
- To elucidate the structural basis of the interaction between CD23 and IgE-Fc.
- To characterize the binding affinities between CD23 and IgE-Fc using biophysical methods.
Main Methods:
- X-ray crystallography was used to determine the structure of the CD23/IgE-Fc complex.
- Isothermal titration calorimetry (ITC) was employed to study binding kinetics and affinities.
Main Results:
- The crystal structure shows two lectin-like 'head' domains of CD23 binding to IgE-Fc.
- Binding affinities between CD23 and IgE-Fc differ significantly (over an order of magnitude).
- The structure reveals asymmetric binding, with only one CD23 head interacting with one IgE-Fc heavy chain.
Conclusions:
- The findings highlight a complex interplay between IgE-Fc binding sites and their affinities.
- This structural and binding information may inform the development of novel therapeutic strategies for allergic diseases.