Subject selection

This prospective observational (cohort) study was conducted in accordance with the Declaration of Helsinki (as revised in 2013) and was approved by institutional review board of Partners Healthcare (IRB2008P000408) under a protocol previously described (5). Informed consent was taken from all the patients.

We recruited a total of 20 volunteers with atopy based on clinical evaluation, documented allergic symptoms to cat and/or dust mite, and a positive skin prick test. Of these, 10 subjects were non-asthmatic and 10 subjects were asthmatic based on clinical evaluation. The asthmatic subjects had mild or moderate persistent asthma based on the National Asthma Education and Prevention Program (NAEPP) management guidelines (3). All subjects were free of any acute respiratory symptoms and had been off of any corticosteroids (including inhaled corticosteroids) for at least 1 month and short acting beta-agonists or antihistamines were held at least 24 hours prior to intervention.