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Safety and efficacy of house dust mite allergen challenge in patients with allergic rhinitis using a novel technique for inhalation studies in the Fraunhofer environmental challenge chamber

: Lueer, Katrin; Biller, Heike; Windt, Horst; Müller, Meike; Badorrek, Philipp; Haefner, Dietrich; Framke, Theodor; Koch, Armin; Ziehr, Holger; Krug, Norbert; Koch, Wolfgang; Hohlfeld, Jens M.

American Journal of Respiratory and Critical Care Medicine 185 (2012), Abstract A4320
ISSN: 1073-449X
ISSN: 0003-0805
ISSN: 1535-4970
American Thoracic Society (ATS International Conference) <2012, San Francisco/Calif.>
Fraunhofer ITEM ()

RATIONALE: There is an increasing demand for studies on indoor allergens, particularly on house dust mite (HDM) allergens, in order to perform basic clinical research and to test anti-allergic drugs under well-controlled conditions. At Fraunhofer ITEM, a novel technique to universally create an atmosphere loaded with allergen particles was recently developed. In brief, aerosol particles of defined size are produced by spray-drying of a solution that contains a licenced allergen extract and lactose as a carrier. The particle size distribution is dependent on the initial droplet size and the solute lactose concentration aiming to have a particle size above 10µm. The aim of this study was to test the safety and efficacy with dose-range finding and reproducibility of this novel HDM challenge in patients with allergic rhinitis in the Fraunhofer Environmental Challenge Chamber (ECC).
METHODS: In a monocenter, placebo-controlled, single-blind, pilot study 18 subjects with allergic rhinitis and sensitization to HDM were exposed in the Fraunhofer ECC for 4 hours to house dust mite allergen (ALK lyophilisiert SQ503 Der p, ALK-Abello, Wedel, Germany) at either 250 SQE/m3, 500 SQE/m3, 1000 SQE/m3, or lactose alone (0 SQE/m3) seven days apart. The dose of 500 SQE/m3 was repeated to investigate reproducibility. Total nasal symptom score (TNSS), anterior rhinomanometry, nasal secretions, exhaled NO, FEV1 and adverse events were assessed prior to and during the exposures.
RESULTS: At a lactose concentration of 10% (w/v) the mass median aerodynamic diameter of allergen particles was 13.5 µm and only 11% of particles were <10µm. Exposure to HDM increased TNSS (mean±SD) to 3.4±1.8, 3.3±2.1, and 3.6±2.0 at 250 SQE/m3, 500 SQE/m3, and 1000 SQE/m3, respectively, while lactose alone did not change TNSS (0.7±0.6). Repeated exposure to 500 SQE/m3 induced a TNSS of 3.0±2.2 which was not different compared to the same previous dose. Objective measures of nasal flow and nasal secretions were in line with clinical symptoms. Exposure to HDM was safe with no relevant change in FEV1.
CONCLUSION: HDM allergen challenge in the Fraunhofer ECC using a novel technique to universally generate allergen atmospheres was safe and specifically induced symptoms in patients with allergic rhinitis. Symptoms were reproducible but no dose-dependency was observed in the tested dose-range. This study provides the methodological basis for further clinical studies using well controlled allergen atmospheres.