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Background: Nearly 60% of birch pollen–allergic patients react exclusively to Bet v 1. With use of the skin blister model, previously only established for installation of crude allergens, we have for the first time characterized the inflammatory response in vivo to recombinant birch pollen allergen, rBet v 1, molecules (rBet v 1 wild type, fragments and trimer). Objective: Our purpose was to examine whether challenge with rBet v 1 derivatives (fragments and trimer) compared with rBet v 1 wild type differs with respect to influx of activated eosinophils and detectable levels of cytokines/chemokines related to allergic inflammation in skin chambers applied to birch pollen–allergic patients. Methods: The skin blister chambers were filled for 2 hours with rBet v 1, the derivatives or PBS and heparin (negative control). The fluids were analyzed after 2 and 8 hours. The number of eosinophils was determined and EG2 and CD69 expression measured by flow cytometry. Cytokines and mediators were analyzed by ELISA and RIA techniques. Results: Comparable numbers of eosinophils were recruited to the chambers challenged with rBet v 1 molecules, but the eosinophils from the rBet v 1 wild-type challenged chambers showed a significantly higher expression of CD69. The levels of eotaxin were similar in all 4 chambers, whereas rBet v 1 wild type induced significantly higher levels of histamine, eosinophil cationic protein, and GM-CSF than the derivatives did. Recombinant Bet v 1 trimer elicited significantly lower levels of IL-4 compared with rBet v1 wild type. Conclusion: Genetically engineered hypoallergenic rBet v 1 derivatives recruited eosinophils analogously with rBet v 1 wild type. However, the derivatives exhibited a lower capacity to activate eosinophils and to release proinflammatory mediators and T helper type 2–derived cytokines. The derivatives may therefore be candidate molecules for specific immunotherapy of birch pollen allergy with reduced risk of inducing allergenic or inflammatory side effects. (J Allergy Clin Immunol 2000;106:101-9.)

Background: Microvascular-epithelial exudation of bulk plasma may characterize inflammatory airway diseases. This study compares the acute allergen challenge–induced mast cell and exudative responses in nasal and bronchial airways. The focus is on α 2 -macroglobulin as an index of luminal entry of plasma exudates. Methods: Separate nasal and bronchial allergen challenges were carried out outside the pollen season in eight patients with pollen-induced seasonal allergic rhinitis. The levels of different-sized plasma proteins (albumin molecular weight, 66,000 d and α 2 -macroglobulin molecular weight, 725,000 d) and tryptase were determined in pre- and postchallenge nasal lavage and bronchoalveolar lavage (BAL) fluids. Diluent and increasing doses of allergen were sprayed into the right nasal cavity, and each challenge was followed by a nasal lavage (volume, 15 ml) with a "nasal pool" device (recovery, >80%). Endobronchial allergen challenge (individual doses) and BAL (volume, 2 × 25 ml) were performed in a lobe bronchus through a fiberoptic bronchoscope (recovery, 30%). Saline challenge and BAL were carried out in the contralateral lung as control. Results: The levels of albumin, α 2 -macroglobulin, and tryptase increased dose-dependently in postchallenge nasal lavage fluids ( p 2 -macroglobulin correlated ( r = 0.98, p 2 -macroglobulin and tryptase, but not albumin, were increased in BAL fluids from the allergen-challenged side ( p Conclusion: Local allergen challenge causes luminal entry of tryptase and α 2 -macroglobulin in the nose and bronchi of patients with allergy. We suggest that mast cell and plasma exudation responses may be similar in human nasal and bronchial airways and that albumin levels (in BAL fluids) may not well reflect the exudation process in bronchial airways. (J ALLERGY CLIN IMMUNOL 1995;96:239-46.)