Inclusion Criteria 

• Age 18-65 years.
• Normal healthy individuals: 
  • No history of asthma or allergic rhinitis;
  • If done previously, they should have a history of negative methacholine responsiveness (PC 20 methacholine >16 mg/ml), negative skin prick test results and/or negative IgE serum tests to 10 common aeroallergens (including house dust mite, several molds, dog, cat, trees, and grasses).
• Patients with ragweed allergic rhinitis:
  • Moderate-to-severe allergic rhinitis (AR) to ragweed.  The clinical diagnosis of AR is established by history, where patients describe the typical seasonal symptoms, and is confirmed with a positive skin prick test and/or positive IgE serum tests to ragweed.
• Patients will be recruited these patients from the clinical practice of the Mayo Clinic Division of Allergic Diseases, as well as from an established database of allergic rhinitis patients.  If previously done, they should have a history of a positive skin prick test and/or positive IgE serum test to ragweed within the past 5 years.  

Exclusion Criteria:

• Received topical or systemic glucocorticoids during the past 8 weeks.
• Previous (within the past 10 years) or current smokers.
• Lower or upper airway infection (e.g., “common cold”) in the last 4 weeks.
• Diagnosed with immunodeficiency or cystic fibrosis.
• Pregnancy.                              
• Asthma.
• Current or past immunotherapy.
• Perennial allergy symptoms.