title: Jug r 2-reactive CD4(+) T cells have a dominant immune role in walnut allergy.
abstract: BACKGROUND
  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.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Benaroya Research Institute at Virginia Mason, Seattle, Wash.
authors.forename: Luis Diego
authors.initials: LD
authors.lastname: Archila
authors.affiliation: Virginia Mason Medical Center, Seattle, Wash; Department of Medicine, University of Washington, Seattle, Wash.
authors.forename: David
authors.initials: D
authors.lastname: Jeong
authors.affiliation: Servei d'Immunologia, CDB, Hospital Clínic de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
authors.forename: Mariona
authors.initials: M
authors.lastname: Pascal
authors.affiliation: Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain; Unitat d'Allèrgia, Servei de Pneumologia, ICT, Hospital Clínic de Barcelona, Barcelona, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Bartra
authors.affiliation: Servei d'Immunologia, CDB, Hospital Clínic de Barcelona, Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
authors.forename: Manel
authors.initials: M
authors.lastname: Juan
authors.affiliation: Virginia Mason Medical Center, Seattle, Wash.
authors.forename: David
authors.initials: D
authors.lastname: Robinson
authors.affiliation: Virginia Mason Medical Center, Seattle, Wash.
authors.forename: Mary L
authors.initials: ML
authors.lastname: Farrington
authors.affiliation: Benaroya Research Institute at Virginia Mason, Seattle, Wash; Department of Medicine, University of Washington, Seattle, Wash. Electronic address: bkwok@benaroyaresearch.org.
authors.forename: William W
authors.initials: WW
authors.lastname: Kwok
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology; D052179:Antigens, Plant / Q000276:immunology / Q000378:metabolism*; D002648:Child; D002999:Clone Cells; D016207:Cytokines / Q000378:metabolism; D018604:Epitope Mapping; D018984:Epitopes, T-Lymphocyte / Q000276:immunology / Q000378:metabolism*; D005260:Female; D050990:GATA3 Transcription Factor / Q000378:metabolism; D006680:HLA Antigens / Q000378:metabolism; D006801:Humans; D016056:Immunodominant Epitopes / Q000276:immunology / Q000378:metabolism*; D007156:Immunologic Memory; D016130:Immunophenotyping; D031324:Juglans / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D021184:Nut Hypersensitivity / Q000276:immunology*; D037182:T-Cell Antigen Receptor Specificity / Q000276:immunology; D058504:Th17 Cells / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology*; D055815:Young Adult
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D016207:Cytokines; D018984:Epitopes, T-Lymphocyte; D050990:GATA3 Transcription Factor; D006680:HLA Antigens; D016056:Immunodominant Epitopes
keywords: Food allergy; Jug r 2; MHC class II tetramers; T cells; epitopes; walnut