title: Immunological characteristics of subjects with asymptomatic skin sensitization to birch and grass pollen.
abstract: BACKGROUND
  Asymptomatic skin sensitization (AS) has been shown to be a risk factor for respiratory allergic disease.
  
  
  OBJECTIVE
  We investigated allergen and recall antigen-driven T cell proliferation, cytokine production and T cell expression of the chemokine receptor CCR4, in cultures derived from symptomatic atopics (SA), subjects with AS and healthy controls (HC). Numbers of allergen-specific precursor T cells in all three groups were also estimated.
  
  
  METHODS
  Peripheral blood mononuclear cells from the three groups were isolated and stimulated with allergen and tetanus toxoid. Proliferation, cytokine production and CCR4 expression were measured by flow cytometry.
  
  
  RESULTS
  A significantly increased proportion of CD4(+) memory T cells proliferated in response to allergen in SA as compared with subjects with AS (P<0.001) and HC (P<0.001). Only in SA was expansion of CD4(+)CCR4(+) T cells, after allergen stimulation observed. SA had higher frequencies of allergen-specific T cells than subjects with AS and HC (P=0.02, for both). With regard to allergen-induced production of T-helper type 1 (Th1) and Th2 cytokines, subjects with AS and HC resembled each other, while differing significantly from SA.
  
  
  CONCLUSIONS
  We conclude, that subjects with AS, although clearly IgE sensitized, have significant diminished numbers of allergen-specific T cells as well as decreased allergen-induced CD4(+) memory T cell proliferation as compared with SA. To a large extent, our findings are capable of explaining the immunological characteristics associated with AS. Our findings may serve as better prognostic markers for subsequent allergic progression, than previously described clinical and paraclinical characteristics.
authors.affiliation: Allergy Clinic, Department 7551, National University Hospital, Copenhagen, Denmark. K.ASSING@RH.DK
authors.forename: K
authors.initials: K
authors.lastname: Assing
authors.forename: C H
authors.initials: CH
authors.lastname: Nielsen
authors.forename: L K
authors.initials: LK
authors.lastname: Poulsen
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology*; D029662:Betula / Q000276:immunology; D029401:Betulaceae / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D049109:Cell Proliferation; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D005260:Female; D006801:Humans; D017493:Leukocyte Common Antigens / Q000032:analysis; D008297:Male; D031784:Phleum / Q000276:immunology; D011058:Pollen / Q000276:immunology*; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D054398:Receptors, CCR4; D019707:Receptors, Chemokine / Q000032:analysis; D006255:Rhinitis, Allergic, Seasonal / Q000276:immunology*; D012867:Skin / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology; D013745:Tetanus Toxoid / Q000276:immunology
chemical_list: D000485:Allergens; C515354:CCR4 protein, human; D016207:Cytokines; D018984:Epitopes, T-Lymphocyte; D054398:Receptors, CCR4; D019707:Receptors, Chemokine; D013745:Tetanus Toxoid; D017493:Leukocyte Common Antigens; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1