Allergen Challenge Chambers (ACC) are used worldwide since many years to test anti-allergic treatment in early clinical development. ACCs provide the advantage of controlled atmospheres with stable allergen load and highly reproducible symptoms during challenges.~The Fraunhofer ACC has been used since more than 20 years to test a range of different anti-allergic treatments, mostly using pollen challenges.~For house dust mite (HDM) challenges, a carrier solution containing lactose or sodium chloride is reconstituted with commercially available HDM allergen. The solution is spray-dried to create allergen loaded lactose or sodium chloride particles of a determined size. Those particles are distributed in the ACC.~Whether lactose or sodium chloride particles alone could induce nasal irritation during allergen challenges, has not been examined. Should allergen-free carrier solutions contribute to nasal symptoms, study results might be confounded. Even more so, if one carrier solution caused more nasal irritation than the other.~To determine if allergen-free carrier solutions alone irritate the nasal mucosa, we expose subjects with allergic rhinitis and house dust mite allergy to three different atmospheres: (1) lactose particles alone, (2) sodium chloride particles alone, and (3) clean air. Also, we aim to document nasal symptoms during challenges with HDM-containing carrier solutions to decide on the best carrier option for future clinical trials.
Single-blind, within-block randomized, clean-air-controlled study to assess the effect of lactose and sodium chloride particles in patients with allergic rhinitis on nasal symptoms when challenged in the Fraunhofer Allergen Challenge Chamber