Identification of an immunodominant IgE epitope of Der f 40, a novel allergen of Dermatophagoides farinae

Ze-Lang Cai; Shan Liu; Wei-Yong Li; Zi-Wen Zhou; Wan-Zhen Hu; Jia-Jie Chen; Kunmei Ji

doi:10.1016/j.waojou.2023.100804

Identification of an immunodominant IgE epitope of Der f 40, a novel allergen of Dermatophagoides farinae

World Allergy Organ J. 2023 Aug 1;16(8):100804. doi: 10.1016/j.waojou.2023.100804. eCollection 2023 Aug.

Authors

Ze-Lang Cai¹, Shan Liu¹, Wei-Yong Li¹, Zi-Wen Zhou¹, Wan-Zhen Hu², Jia-Jie Chen¹, Kunmei Ji¹

Affiliations

¹ Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Shenzhen University Medical School, Shenzhen 518060, China.
² Shenzhen University General Hospital, Shenzhen 518060, China.

Abstract

Background: House dust mites (HDMs), including Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f) species, represent a major source of inhalant allergens that induce IgE-mediated anaphylactic reactions. HDM allergen identification is important to the diagnosis and treatment of allergic diseases. Here, we report the identification of a novel HDM allergen, which we suggest naming Der f 40, and its immunodominant IgE epitopes.

Methods: The recombinant protein Der f 40 was expressed using a pET prokaryotic expression system and purified with Ni-NTA resins. IgE binding activity was evaluated by IgE-western blot, dot-blot, and ELISA. Mast cell activation testing was performed to assess the cellular effects of IgE binding in mouse bone marrow derived mast cells (BMMCs) expressing human FcεRI. IgE binding assays were performed with truncated and hybrid Der f 40 protein molecules to find immunodominant IgE epitopes.

Results: A 106-amino acid (aa) recombinant Der f Group 40 protein (rDer f 40) was obtained (GenBank accession No. XP_046915420.1) as thiredoxin-like protein. Der f 40 was shown to bind IgE from HDM allergic serum in vitro (9.68%; 12/124 in IgE-ELISA), and shown to promote the release of β-hexosaminidase from BMMCs dose-dependently when administered with HDM allergic sera. The Der f Group 40 protein was named Der f 40 and listed in the World Health Organization and International Union of Immunological Societies (WHO/IUIS) Allergen Nomenclature Sub-committee. IgE binding assays with Der f 40-based truncated and hybrid proteins indicated that IgE binding epitopes are likely located in the C-terminal region and dependent on conformational structure. The 76-106-aa region of C-terminus was identified as an immunodominant IgE epitope of Der f 40.

Conclusion: A novel HDM allergen with robust IgE binding activity was identified and named Der f 40. An immunodominant IgE epitope of Der f 40 with conformational dependency was identified in the C-terminus (aa 76-106). These findings provide new information that may be useful in the development of diagnostic and therapeutic agents for HDM allergy.

Keywords: Allergens; Dust mite allergy; Immunodominant epitopes; Immunoglobulin E.