HDM and Silver Birch NAC standardisation
Research type
Research Study
Full title
Nasal Allergen Challenge: standardisation for house dust mite and silver birch allergen extracts
IRAS ID
84388
Contact name
Guy Scadding
Contact email
Sponsor organisation
Guy's and St Thomas' NHS Foundation Trust, Royal Brompton Hospital
Clinicaltrials.gov Identifier
Duration of Study in the UK
0 years, 5 months, 2 days
Research summary
Summary of Research
Nasal allergy (allergic rhinitis) is the most common immunological condition in the UK, affecting at least 1 in 4 people. Nasal allergen challenge involves spraying small amounts of purified allergen extracts into the nose and measuring symptoms and changes in nasal airway. We have standardised nasal challenge using commercially available grass pollen allergy tablets, Grazax. In this study, we intend to do the same for two other common causes of allergic rhinitis, house dust mite and silver birch tree pollen. We will measure the effects of nasal challenge using the tablet allergen extracts for house dust mite (Acarizax) and silver birch pollen (Itulazax) and identify optimum doses for future studies looking at treatment interventions.Summary of Results
Nasal allergen challenge (NAC) is used to investigate the effects of allergen exposure and check if and how allergy treatments work. This study aimed to establish responses to increasing doses of silver birch (SB) pollen and house dust mite (HDM) extracts using commercially available allergen tablets.We recruited sixteen volunteers with HDM‐induced allergic rhinitis (AR) and 15 volunteers with SB pollen‐induced AR. They underwent graded up‐dosing NAC with extracts derived from HDM allergen (Acarizax®) and SB (Itulazax®) tablets, respectively. We recorded their nasal allergy symptoms and their ability to sniff through a special device called a peak nasal inspiratory flow (PNIF) meter during the testing. We calculated the most common dose of each allergen that produced a symptom score of 7 or more out of 12. We then tested this dose on non-allergic individuals to confirm that there was no non-allergic, irritant effect, and on individuals who were allergic to another allergen, to show that the effect was allergen specific.
We found that a median allergen concentration of 1500 units per millimetre evoked symptoms of at least 7 out of 12 for both allergens; this dose also produced very similar falls in ability to sniff through the nose, a 63.15% fall for SB and a 63.99% fall for HDM. The same doses had no effect on non-allergic individuals or when given to individuals sensitised to the other allergen but not the one being tested.
The study shows that commercially available allergen tablets can be used for nasal challenge tests and provides researchers with dose-response curves on which to base future interventional studies.
REC name
West Midlands - Black Country Research Ethics Committee
REC reference
22/WM/0166
Date of REC Opinion
19 Aug 2022
REC opinion
Further Information Favourable Opinion