title: Skin testing with recombinant allergens rBet v 1 and birch profilin, rBet v 2: diagnostic value for birch pollen and associated allergies.
abstract: OBJECTIVE
  This study assesses the value of two recombinant birch allergens for diagnosis of patients sensitized to birch pollen with or without associated food allergy.
  
  
  METHODS
  Fifty-one patients with positive skin test responses to Betulaceae and seven nonallergic control subjects were investigated; specific IgE antibodies were evaluated by specific immunoassay and blot immunodetection.
  
  
  RESULTS
  Among 51 patients, 47 reacted to rBet v 1 and 10 to rBet v 2. Seven patients reacted to both recombinant allergens. In skin prick tests we found a correlation between the wheal produced by the commercial birch extract and the wheal produced by rBet v 1. Among 47 patients with positive test responses to rBet v 1, 83% had IgE binding to the Bet v 1 protein as determined by immunoblotting. Among 10 patients sensitized to rBet v 2, six had IgE binding to Bet v 2. Eleven patients with negative results, as determined by immunoblotting, had low levels of birch IgE in the sera (less than 10 kU/L) and low concentrations of IgE to rBet v 1 or rBet v 2 in ELISA. The nonallergic control subjects (n = 7) did not react to rBet v 1 or rBet v 2 in skin prick tests, nor did they have detectable amounts of specific IgE to rBet v 1 or rBet v 2. Histamine release tests confirmed sensitization to Bet v 1 in two patients with discordant results; for Bet v 2, one patient had positive results only at a high concentration, and one had results that remained negative. Thirty-four patients had birch pollinosis, and all reacted to rBet v 1. Patients who were monosensitized to birch never reacted to rBet v 2. Sensitization to rBet v 2 was only found in patients who reacted to other pollens (mainly grass). Twenty-nine patients demonstrated allergy to apples, cherries, or hazelnuts; and all reacted to rBet v 1. Among 11 patients with allergy to Umbelliferae, only three reacted to rBet v 2.
  
  
  CONCLUSIONS
  Use of the two recombinant allergens (rBet v 1 and rBet v 2) always permits the diagnosis of birch sensitization. Sensitization to rBet v 1 is specific for birch and Rosaceae allergies, whereas sensitization to birch profilin, Bet v 2, is encountered in multisensitized subjects and is not always related to Umbelliferae allergy.
authors.affiliation: Pavillon Laennec, Hôpitaux Universitaires de Strasbourg, France.
authors.forename: G
authors.initials: G
authors.lastname: Pauli
authors.forename: J P
authors.initials: JP
authors.lastname: Oster
authors.forename: P
authors.initials: P
authors.lastname: Deviller
authors.forename: S
authors.initials: S
authors.lastname: Heiss
authors.forename: J C
authors.initials: JC
authors.lastname: Bessot
authors.forename: M
authors.initials: M
authors.lastname: Susani
authors.forename: F
authors.initials: F
authors.lastname: Ferreira
authors.forename: D
authors.initials: D
authors.lastname: Kraft
authors.forename: R
authors.initials: R
authors.lastname: Valenta
mesh_terms: D000328:Adult; D000485:Allergens / Q000008:administration & dosage*; D000918:Antibody Specificity; D052179:Antigens, Plant; D003285:Contractile Proteins; D005260:Female; D005512:Food Hypersensitivity / Q000175:diagnosis / Q000276:immunology; D006801:Humans; D007428:Intradermal Tests; D008297:Male; D008840:Microfilament Proteins / Q000008:administration & dosage* / Q000276:immunology; D010940:Plant Proteins / Q000008:administration & dosage* / Q000276:immunology; D051304:Profilins; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000276:immunology; D006255:Rhinitis, Allergic, Seasonal / Q000175:diagnosis* / Q000276:immunology
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D003285:Contractile Proteins; D008840:Microfilament Proteins; D010940:Plant Proteins; D051304:Profilins; D011994:Recombinant Proteins; C061312:Bet v 1 allergen, Betula