Critical and direct involvement of the CD23 stalk region in IgE binding

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• 作者：Regina Selb ; PhD^a ; Julia Eckl-Dorna ; MD ; PhD^a ; Teresa E. Twaroch ; PhD^b ; Christian Lupinek ; MD^b ; Andrea Teufelberger ; MSc^c ; ^&lowast ; ; Gerhard Hofer ; MSc^c ; Margarete Focke-Tejkl ; PhD^b ; Barbara Gepp ; PhD^d ; Birgit Linhart ; PhD^b ; Heimo Breiteneder ; PhD^d ; Adolf Ellinger ; MD^e ; Walter Keller ; PhD^c ; Kenneth H. Roux ; PhD^f ; Rudolf Valenta ; MD^b ; ^{Rudolf.valenta@meduniwien.ac.at} ; Verena Niederberger ; MD^a
• 关键词：CD23 ; allergy ; IgE ; low-affinity IgE receptor ; B cell ; allergen
• 刊名：Journal of Allergy and Clinical Immunology
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：139
• 期：1
• 页码：281-289.e5
• 全文大小：2945 K
• 卷排序：139

文摘

The low-affinity receptor for IgE, FcεRII (CD23), contributes to allergic inflammation through allergen presentation to T cells, regulation of IgE responses, and enhancement of transepithelial allergen migration.ObjectiveWe sought to investigate the interaction between CD23, chimeric monoclonal human IgE, and the corresponding birch pollen allergen Bet v 1 at a molecular level.MethodsWe expressed 4 CD23 variants. One variant comprised the full extracellular portion of CD23, including the stalk and head domain; 1 variant was identical with the first, except for an amino acid exchange in the stalk region abolishing the N-linked glycosylation site; and 2 variants represented the head domain, 1 complete and 1 truncated. The 4 CD23 variants were purified as monomeric and structurally folded proteins, as demonstrated by gel filtration and circular dichroism. By using a human IgE mAb, the corresponding allergen Bet v 1, and a panel of antibodies specific for peptides spanning the CD23 surface, both binding and inhibition assays and negative stain electron microscopy were performed.ResultsA hitherto unknown IgE-binding site was mapped on the stalk region of CD23, and the non–N-glycosylated monomeric version of CD23 was superior in IgE binding compared with glycosylated CD23. Furthermore, we demonstrated that a therapeutic anti-IgE antibody, omalizumab, which inhibits IgE binding to FcεRI, also inhibited IgE binding to CD23.ConclusionOur results provide a new model for the CD23-IgE interaction. We show that the stalk region of CD23 is crucially involved in IgE binding and that the interaction can be blocked by the therapeutic anti-IgE antibody omalizumab.