Evaluation Of House Dust Mite Dose Response In The Environmental Exposure Unit

As a controlled allergen challenge facility, the Environmental Exposure Unit (EEU) is a valuable model to investigate allergic rhinitis (AR). While seasonal allergens have been previously studied in the EEU, here we sought to evaluate the clinical manifestations of house dust mite (HDM)-induced AR in the HDM-EEU. HDM-allergic volunteers, deemed eligible to participate based on relevant clinical history and positive skin prick test (SPT) results, and healthy control participants were invited to one of two exposure sessions in the HDM-EEU. Following a baseline collection, symptomatic data including Total Nasal Symptom Score (TNSS) and Peak Nasal Inspiratory Flow (PNIF) were collected every half hour for the 3-hour HDM exposure, on an hourly basis until 12 hours post-exposure, and at 24 hours. Following the screening visit, 20 HDM-allergic and 4 non-allergic participants were exposed to a moderate target of HDM while 24 atopics and 6 non-atopics received a high HDM dose. Both groups of allergics had significantly greater (moderate target: p<0.01; high target: p<0.001) SPT wheal sizes against D. pteronyssinus and D. farinae compared to controls. Elevated TNSS responses were sustained for up to 5 hours for allergics exposed to either condition, however those in the high target session had significantly greater mean TNSS scores at hours 2.5 and 3 (p<0.05 and p<0.01, respectively). PNIF fall (%) was significantly decreased for the high target HDM-allergics for hours 2 (p<0.05), 2.5 (p<0.05), and 3 (p<0.01). The HDM-EEU can be used to elicit a measurable dose-dependent symptomatic response from HDM-allergic participants.