title: Food allergen (peanut)-specific TH2 clones generated from the peripheral blood of a patient with peanut allergy.
abstract: BACKGROUND
  Increasing evidence indicates a prominent role of allergen-specific TH2 cells, with high IL-4 and IL-5 production and low interferon-gamma production, in the regulation of IgE and eosinophil production in allergic disorders. However, most studies have concentrated on T cells reactive with inhalation allergens, whereas little is known about the properties of food allergen-reactive T cells.
  
  
  OBJECTIVE
  In this study we therefore characterized peanut-specific T cells, cloned from a patient with severe peanut allergy.
  
  
  METHODS
  Peripheral blood mononuclear cells from patients with peanut allergy and nonallergic individuals were stimulated with crude peanut extract (CPE) to compare the proliferative responses and to select a suitable patient for the cloning of CPE-specific T cells. The resultant panel of CPE-reactive T-lymphocyte clones was serologically phenotyped by flow cytometry and analyzed for cytokine secretion by ELISA.
  
  
  RESULTS
  The patients' peripheral blood mononuclear cells showed a dose-dependent proliferation response to CPE, which was significantly higher (p < 0.05) than in peripheral blood mononuclear cells of nonallergic donors. The CPE-specific T-lymphocyte clones generated from the selected patient were all CD4+/CD8- T helper cells with a TH2 cytokine profile, secreting high amounts of IL-4 and IL-5, but little or no interferon-gamma.
  
  
  CONCLUSIONS
  This study demonstrates that peanut-specific T cells do occur in the peripheral blood of patients with peanut allergy and suggests an increased frequency of these T cells in patients compared with nonallergic control subjects. The CD4+ phenotype and the TH2 cytokine profile of the CPE-specific T-lymphocyte clones suggest a functional role of allergen-specific TH2 cells in the pathophysiology of food allergy, similar to the function of inhalation allergen-specific TH2 cells.
authors.affiliation: Netherlands Organization for Applied Scientific Research, Nutrition and Food Research Institute, Zeist.
authors.forename: E C
authors.initials: EC
authors.lastname: de Jong
authors.forename: S
authors.initials: S
authors.lastname: Spanhaak
authors.forename: B P
authors.initials: BP
authors.lastname: Martens
authors.forename: M L
authors.initials: ML
authors.lastname: Kapsenberg
authors.forename: A H
authors.initials: AH
authors.lastname: Penninks
authors.forename: E A
authors.initials: EA
authors.lastname: Wierenga
mesh_terms: D000328:Adult; D000954:Antigens, Surface / Q000378:metabolism; D010367:Arachis / Q000276:immunology*; D002999:Clone Cells / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D000939:Epitopes / Q000097:blood; D005260:Female; D005512:Food Hypersensitivity / Q000097:blood / Q000276:immunology*; D006801:Humans; D008213:Lymphocyte Activation; D008297:Male; D010940:Plant Proteins / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology* / Q000378:metabolism
chemical_list: D000954:Antigens, Surface; D016207:Cytokines; D000939:Epitopes; D010940:Plant Proteins