Jug r 2–reactive CD4+ T cells have a dominant immune role in walnut allergy

• Published in: Journal of allergy and clinical immunology Vol. 136; no. 4; pp. 983 - 992.e7
• Main Authors: Archila, Luis Diego, Jeong, David, Pascal, Mariona, Bartra, Joan, Juan, Manel, Robinson, David, Farrington, Mary L., Kwok, William W.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2015; Elsevier Limited
• Subjects: Adolescent; Adult; Allergens - immunology; Allergy and Immunology; Antigens, Plant - immunology; Antigens, Plant - metabolism; Child; Clone Cells; Cytokines - metabolism; Epitope Mapping; epitopes; Epitopes, T-Lymphocyte - immunology; Epitopes, T-Lymphocyte - metabolism; Female; Food allergies; Food allergy; GATA3 Transcription Factor - metabolism; Genotype & phenotype; HLA Antigens - metabolism; Humans; Immunodominant Epitopes - immunology; Immunodominant Epitopes - metabolism; Immunologic Memory; Immunophenotyping; Jug r 2; Juglans; Juglans - immunology; Lymphocyte Activation; Lymphocytes; Male; MHC class II tetramers; Middle Aged; Nut Hypersensitivity - immunology; Peptides; Proteins; T cells; T-Cell Antigen Receptor Specificity - immunology; Th17 Cells - immunology; Th2 Cells - immunology; walnut; Young Adult; Spain; Food allergy; RORC; T cells; Jug r 2; walnut; epitopes; PE; TCC; MHC class II tetramers; Teff; ICS; CRTH2; TGEM; TCM; RAR-related orphan receptor C; Intracellular cytokine staining; Effector T; Chemoattractant receptor–homologous molecule expressed on T H2 cells; T CM; Phycoerythrin; Tetramer-guided epitope mapping; T-cell clone; Central memory T
• ISSN: 0091-6749; 1097-6825
• DOI: 10.1016/j.jaci.2015.01.029

Allergic reactions to walnut can be life-threatening. Although IgE epitopes of walnut have been studied, CD4+ T cell–specific epitopes for walnut remain uncharacterized. In particular, the relationship of both phenotype and frequency of walnut-specific T cells to the disease have not been examined. We sought to provide a thorough phenotypic analysis for walnut-reactive T cells in allergic and nonallergic subjects, particularly the relationship of phenotypes and frequencies of walnut-specific T cells with the disease. The CD154 upregulation assay was used to examine CD4+ T-cell reactivity toward the walnut allergens Jug r 1, Jug r 2, and Jug r 3. A tetramer-guided epitope mapping approach was used to identify HLA-restricted CD4+ T-cell epitopes in Jug r 2. Direct ex vivo staining with peptide–major histocompatibility complex class II tetramers enabled comparison of the frequency and phenotype of Jug r 2–specific CD4+ T cells between allergic and nonallergic subjects. Jug r 2–specific T-cell clones were also generated, and mRNA transcription factor levels were assessed by using quantitative RT-PCR. Intracellular cytokine staining assays were performed for further phenotypic analyses. Jug r 2 was identified as the major allergen that elicited CD4+ T-cell responses. Multiple Jug r 2 T-cell epitopes were identified. The majority of these T cells in allergic subjects have a CCR4+ phenotype. A subset of these T cells express CCR4+CCR6+ irrespective of the asthmatic status of the allergic subjects. Intracellular cytokine staining confirmed these TH2-, TH2/TH17-, and TH17-like heterogenic profiles. Jug r 2–specific T-cell clones from allergic subjects mainly expressed GATA3, nonetheless, a portion of T-cell clones both GATA3 and RAR-related orphan receptor C (RORC) or RORC alone, confirming the presence of TH2, TH2/TH17, and TH17 cells. Jug r 2–specific responses dominate walnut T-cell responses in patients with walnut allergy. Jug r 2 central memory CD4+ cells and terminal effector T cells were detected in peripheral blood, with the central memory phenotype as the most prevalent phenotype. In addition to conventional TH2 cells, TH2/TH17 and TH17 cells were also detected in nonasthmatic and asthmatic patients with walnut allergy. Understanding this T-cell heterogeneity might render better understanding of the disease manifestation.