Environmental exposure chamber
The ALYATEC EEC is a new generation EEC located in Strasbourg, France. Its capacity and allergen exposure conditions are described elsewhere.16, 17 In this study, patients were exposed to the same batch of lyophilized birch allergen GMP extract (100 IR;Stallergenes Greer ®), diluted in saline serum, as the one used for the CAC. Before the patients entered the EEC, the exposure was initiated in order to reach a plateau of airborne birch allergen and then maintained for a maximum of 4 hours. A homogeneous allergen concentration was ensured by using particle counters and online measurements of the temperature, relative humidity, and air exchange as described previously.16, 17 The birch allergen was collected on five glass fiber filters located next to the patients’ chairs during exposure to determine the Bet v 1 concentration using ELISA (Indoor Biotechnologies®, Charlottesville, VA, USA), after each allergen exposure. The concentration of the Bet v 1 airborne exposure was estimated to be 60 ng/m3. During EEC allergen exposure, the conjunctival response was assessed every 10 minutes during the first hour and then every 20 minutes.