title: Dissection of the grass allergen-specific immune response in patients with allergies and control subjects: T-cell proliferation in patients does not correlate with specific serum IgE and skin reactivity.
abstract: BACKGROUND
  Pollinosis, caused by grasses of the Poaceae family, is a problem worldwide. The relative importance of grass groups 1 and 5 major allergens is well established. However, not much is known about the recognition of these allergens by T cells and whether this T-cell reactivity correlates with skin reactivity and serum IgE levels.
  
  
  OBJECTIVE
  The aim of this study was to characterize the cross-reactive, grass allergen-specific T-cell responses from patients allergic to grass and nonatopic individuals and to investigate whether these responses correlate with grass-specific IgE and skin reactivity.
  
  
  METHODS
  Skin prick test wheal areas and grass-specific serum IgE levels were determined in all patients (n = 21) and nonallergic control donors (n = 20). Peripheral blood mononuclear cells were isolated and stimulated with grass allergen extracts (Phleum pratense, Poa pratensis, Lolium perenne) and immunoaffinity-purified group 5 allergens, and the production of type 1 and type 2 cytokines was determined in the patient group.
  
  
  RESULTS
  Donors allergic to grass showed increased T-cell-proliferative responses to grass allergens compared with nonatopic control subjects. We find it interesting that the magnitude of the patients' T-cell responses could not be correlated with the individual skin prick test areas and specific serum IgE levels, and several patients with allergies to grass had group 5-specific T-cell responses in the absence of group 5-specific IgE. The absence of a correlation between T-cell proliferation and IgE levels or skin prick test results may in part be explained by the finding that patients predominantly produced IL-5 in response to Phl p 5, the major allergen, and predominantly IFN-gamma in response to Phl p extract. In general, all donors responded equally well to all three grasses. Additional experiments with Phl p 5-specific T-cell lines indicated that the equal proliferation of peripheral blood mononuclear cells to all three species is the direct result of cross-reactivity.
  
  
  CONCLUSIONS
  Grass allergen-specific T-cell responses are highly cross-reactive, and patients with allergies exhibit higher responses than nonallergic donors, suggesting that T cells are involved in the allergic reaction to grass group 5 allergens. However, group 5-specific T-cell responses are also found in donors without group 5-specific IgE, and the patients' grass-specific T-cell responses and cytokine production do not correlate to skin reactivity or to concentrations of grass-specific IgE.
authors.affiliation: ALK ABELLO Group, Hørsholm, Denmark.
authors.forename: P A
authors.initials: PA
authors.lastname: Würtzen
authors.forename: R J
authors.initials: RJ
authors.lastname: van Neerven
authors.forename: J
authors.initials: J
authors.lastname: Arnved
authors.forename: H
authors.initials: H
authors.lastname: Ipsen
authors.forename: S H
authors.initials: SH
authors.lastname: Sparholt
mesh_terms: D000485:Allergens / Q000009:adverse effects / Q000276:immunology*; D003429:Cross Reactions; D016207:Cytokines / Q000096:biosynthesis; D006801:Humans; D006967:Hypersensitivity / Q000097:blood / Q000276:immunology*; D007073:Immunoglobulin E / Q000097:blood* / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology*; D010641:Phenotype; D010940:Plant Proteins / Q000276:immunology; D006109:Poaceae / Q000276:immunology*; D011058:Pollen / Q000276:immunology*; D012882:Skin Tests; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000485:Allergens; D016207:Cytokines; C076049:Phl p V protein, Phleum pratense; D010940:Plant Proteins; D007073:Immunoglobulin E