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.