Threshold Concentration of Ragweed Pollen for Inducing Allergic Symptoms: Initial Data Using an Allergen Challenge...

Area of Science:

• Allergy and Immunology
• Environmental Health
• Respiratory Medicine

Background:

• Climate change may increase allergenic plant spread, like ragweed.
• Ragweed pollen is often considered more allergenic than birch pollen.
• Determining precise pollen threshold concentrations for allergic rhinitis symptoms is challenging.

Purpose of the Study:

• To explore ragweed pollen threshold concentrations for triggering allergic rhinitis symptoms.
• To compare ragweed pollen allergenicity with birch pollen using a controlled environmental chamber.
• To evaluate the utility of a modified Fraunhofer Allergen Challenge Chamber (ACC) for low pollen concentration studies.

Main Methods:

• Two ragweed pollen allergic rhinitis patients were exposed to varying ragweed pollen concentrations in the Fraunhofer ACC.
• Total Nasal Symptom Score (TNSS), nasal secretion, and peak nasal inspiratory flow were monitored.
• Ex-vivo basophil activation tests (CD63 expression) were performed using ragweed pollen, Amb a 1, birch pollen, and Bet v 1.

Main Results:

• Ragweed pollen exposure elicited varying Total Nasal Symptom Score (TNSS) values across different concentrations.
• The mean effective concentration (EC50) for CD63 expression was 277 pollen/ml for ragweed pollen and 11 pollen/ml for birch pollen.
• The proportion of Amb a 1 in ragweed pollen was 0.17%, and Bet v 1 in birch pollen was 1.96%.

Conclusions:

• The modified Fraunhofer ACC is suitable for investigating pollen threshold concentrations.
• The study did not confirm the assumption that ragweed pollen has a lower threshold for triggering symptoms than birch pollen.
• Larger studies are required to establish reliable ragweed pollen threshold concentrations.