Stabilizing Fel d1 Levels in a Cat Allergen Exposure Chamber

RATIONALE: Naturalistic exposure to cat allergen in a controlled environment is optimal for assessing patient responses. However, maintaining control of Feld1 levels remain problematic as reported values can vary significantly within and between chambers. This study aims to assess new and previous methods to aerosolize Feld1 in our Natural Exposure Chamber. The best method for maintaining dander levels will be utilized for future cat allergen exposure studies.

METHODS: The chamber, volume 14.7 m³ was designed and built to accommodate two neutered cats and 1-2 subjects. Samples were obtained at 3 locations in the chamber using portable air samplers (Gillian 5000) with glass fiber filters (Millipore), flow rate 4 L/min. Feld1 was quantified using ELISA (Indoor Biotechnologies). Over 20 weeks, 30-minute air samples and floor and wall swabs were collected to measure Feld1. Fans and blanket shaking were evaluated as means to aerosolize dander.

RESULTS: With no disturbance, air Feld1 levels were mostly below the limit of detection in the 20 weeks following the cats’ introduction to the room. Over the same time, wall (1.7 to 19.2 ng/m²) and floor Feld1 (15.1 to 138.2 ng/m²) increased. Fans placed 1.5 and 7 feet above the floor aerosolized Feld1 (12.6 ± 19.8 and 9.17 ± 6.1 ng/m³, respectively). Shaking the cats’ blankets generated 45.9 ± 60.1 ng/m³ in the air and shaking every 15 minutes 111.7 ± 46.3 ng/m³.

CONCLUSIONS: Feld1 increased on walls and floor over 20 weeks of cat residence but required intervention for aerosolization. Blanket shaking generated higher levels of Feld1 in the air.