Response to ragweed allergen provocation in the Red Maple Trials Allergen Challenge TheatreTM
Poster Feb 24, 2015
Suzanne Kelly, PHD;Jacob Karsh, MDCM, FRCPC; Jimmy Yang, MBA; William H. Yang, MD, FRCPC, FAAAAI
Rationale: Allergen challenge chambers expose allergen-sensitive subjects to a predetermined concentration of allergen in a closed, controlled environment and provide a mechanism to induce clinical symptoms and measure the effect of medication.
Methods: We evaluated the response of ragweed-allergic subjects to two ragweed challenges in the Red Maple Trials Allergen Challenge Theatre. A provincial Ethics Board approved the study. After signing informed consent, patients with a history of ragweed allergy, not on allergy medications and with a positive skin prick test to ragweed antigen (> 3 mm) were exposed to ragweed pollen in a 3-hour priming session. Total nasal (TNSS), ocular and respiratory symptom scores (TRSS) were recorded at baseline and every 30 minutes during the challenge. Those with a TNSS > were then selected for 2 further 4-hour challenges.
Results: 48/76 subjects evaluated underwent the priming challenge. Thirty-three subjects achieving a peak TNSS ≥5 were selected for two subsequent 4-hour challenges. Baseline TNSS (mean± SD) was 1.70 ±1.34 and 2.53±1.76 in challenges 1 and 2, respectively. Baseline TRSS values were 2.00± 1.66 and 3.60±2.69 respectively. Symptom scores reached a plateau by 120 minutes and remained steady for the remainder of the 240-minute exposure period. Plateau TNSS was 6.28±0.20 for Challenge 1and 6.19±0.24 for Challenge 2. Similarly, TRSS values were 9.10±0.20 and 9.11± 0.33, respectively.
Conclusions: The Red Maple Trials allergen exposure theatre demonstrated the capacity to induce symptoms of appropriate intensity upon allergen challenge. Our chamber with a seating capacity of 100 places has the ability to evaluate large test groups at a time.