Abstract
BACKGROUND: Allergen inhalation tests are a valuable research tool. The allergen dose producing an early asthmatic response (EAR) can be predicted from methacholine responsiveness and allergen skin test endpoint (STE). The Wright(®) jet nebulizer, which is both inefficient and increasingly difficult to obtain, has been used historically. We assessed the Solo(®) vibrating mesh nebulizer as an alternative for allergen and methacholine challenges. METHODS: Eighteen mild atopic asthmatics completed the study. Doubling concentration allergen prick skin tests were performed to determine the STE in allergen units/mL. The Wright(®) protocol was used to measure the methacholine provocation dose causing a 20% forced expired volume in one second (FEV(1)) fall (PD(20)) (μg) and the allergen PD(20) (units). The Solo(®) protocol (0.5 mL nebulized to completion, tidal breathing inhalation) was used to determine both methacholine PD(20) and allergen PD(20). The nebulizer order was randomized and separated by ≥ 2 weeks. RESULTS: All data were log transformed. The allergen PD(20), predicted from the methacholine PD(20) and the STE, was within 2 doubling doses of the PD(20) measured with the Wright(®) and 2.64 doubling doses of that measured with Solo(®). The Wright(®) allergen PD(20) correlated with the Wright(®) methacholine PD(20) (r = 0.74) and the STE (r = 0.78) and more strongly with the product of the two (Wright(®) methacholine PD(20) × STE, r = 0.91, p < 0.00001). The Solo(®) allergen PD(20) showed similar relationships with the Solo(®) methacholine PD(20) (r = 0.61), the STE (r = 0.75) and the product of the two (Solo(®) methacholine PD(20) × STE, r = 0.83, p < 0.00002). The Wright(®) and the Solo(®) methacholine geometric mean PD(20)s were not significantly different (49.3 and 54.5 μg respectively, p = 0.62). The Wright(®) allergen PD(20) was slightly but significantly lower than the Solo(®) allergen PD(20) (geometric means 6.7 and 10.5 units respectively, p = 0.003). CONCLUSION: The Solo(®) allergen PD(20) showed the same relationship with methacholine responsiveness and STE as did the Wright(®). The Solo(®) allergen PD(20) was slightly but significantly higher than the Wright(®) allergen PD(20). The Solo(®) vibrating mesh nebulizer was well tolerated and is an acceptable alternative for allergen challenge.Trial registration clinicaltrials.gov: NCT03491358.