Nasal Allergen Challenge in Rhinitic Subjects

Comparative Responses to Nasal Allergen Challenge in Allergic Rhinitic Subjects With or Without Asthma

Background: Nasal allergen challenge (NAC) is useful to study the pathophysiology of rhinitis, and multiple challenges may more adequately approximate natural exposure.

Objective: To determine the effect of 4 consecutive daily NAC, on clinical and inflammatory parameters in rhinitics with or without asthma.

The study will be performed outside the pollen season. On a baseline visit, 2 to 7 days prior to control challenge, allergy skin prick tests and methacholine inhalation test will be done. Prior to first allergen challenge, skin titration will be done using tenfold dilutions of the allergen chosen for nasal challenges. Subsequent to baseline visit, a control challenge will be done, followed, a week later, by repeated NACs. NACs will be done over 4 consecutive days, in the morning. Nasal peak inspiratory flows (NPIF), oral peak expiratory flows (PEF), and symptoms will be recorded at baseline and at regular intervals over 7 hours post-challenge on each challenge day. Induced sputum and nasal lavage specimen will be obtained 7 hours following the control challenge and the first and last NAC.

Inclusion Criteria:

• To have a positive reaction to one or more allergen on prick tests.
• Non smokers
• No respiratory track infection for at least one month prior to the study.
• Positive reaction to cat hair and/or house dust mite (Dermatophagoides pteronyssinus) aeroallergens on allergy skin prick tests and report rhinitis symptoms when exposed to an environment containing this allergen.
• Asthmatic subjects using only inhaled beta-2 agonists on an as needed basis for their asthma treatment.
• Asthmatic subjects with a history of asthma of at least 6 months.
• Asthmatic subjects with PC20 methacholine lower or equal to 8 mg/ml.
• Allergic rhinitic subjects never experienced any asthma symptoms or took any asthma medication in the past.
• Allergic rhinitic subjects with a provocative concentration of methacholine (PC20 higher than 16 mg/ml.

Exclusion Criteria:

• Smokers or ex smokers less than 6 months or more than 10 pack-years.
• Asthmatic subjects using or used in the past 3 months inhaled or oral corticosteroids.