Asthma population
Subjects with asthma were recruited from the Asthma Clinic at the University of Alberta following written informed consent. This asthma study was approved by the University of Alberta Human Ethics Review Board (PRO1784). Lung function testing was performed and blood obtained for complete blood count (CBC), serum IgE measurement, immune cell profiling and whole blood RNA preparation. Severe asthma was defined as patients on high dose inhaled corticosteroids (ICS, ≥ 1000 µg/day fluticasone equivalent), a 2nd line controller (long-acting β agonist, leukotriene modifier, theophylline, tiotropium), anti-type 2 therapy (anti-IgE, anti-IL-5) and/or oral corticosteroid (OCS) therapy for ≥ 50% of the previous year whose symptoms remain uncontrolled despite this therapy [2].