Study participants
The study population consisted of 20 subjects (mean [SD] age, years (range); 28.0 [7.1] (19-46); ten men and ten women) suffering from seasonal allergic rhinitis to grass pollen. The study was approved by the local Research Ethics Committee. Informed written consent was obtained from all subjects before their participation.
Inclusion criteria were a history of summer grass pollen allergic rhinitis for at least 2 years confirmed by a positive skin prick test to grass pollen extract (Stallergenes) i.e. >3 mm weal compared with the negative control and positive specific IgE-antibodies to grass pollen, assessed by Phadia (mean [SD], kU/L (range); 16.5 ± 23.4 (0.4 -100). Patients were excluded if they had current symptoms of rhinitis, other nasal or systemic disease, asthma requiring regular inhaled corticosteroids, abnormal pulmonary function, other respiratory conditions, current medication including anti-allergic medication, specific immunotherapy in the previous 5 years, smoking history in the past 6 months, were pregnant or breastfeeding women. None of the subjects had exposure to other relevant respiratory allergens and to avoid natural allergen provocation, all subjects were studied outside the grass-pollen season. At screening, participants were examined, including a nasal examination to rule out any nasal disease or evidence of active rhinitis. Throughout the whole study period, subjects were not allowed to take any medication.