Respiratory and nasal symptoms during live-cat versus milled cat hair exposure

<bold>Introduction:</bold> The Red Maple Trials NEC is a fixed exposure chamber where allergen shed from live cats is aerosolized using a modified robot vacuum. The Mobile NEC™ is a portable allergen exposure tent, where milled cat hair is aerosolized in a similar manner. This study was designed to compare the allergic response to cat antigen provocation in the Mobile NEC™ and the Fixed NEC™. <bold>Method:</bold> Cat allergic subjects (skin-prick test mean diameter ≥5mm) underwent a 2-hour exposure to cat allergen in the Fixed NEC and the Mobile NEC. Fel d 1 measured by sampling pumps was quantified by ELISA. Nasal, ocular and respiratory symptoms were measured every 10 minutes and spirometry every 20 minutes. Subjects with an FEV1 fall ≥20% of baseline or low nasal symptom scores during the first challenge were not rechallenged. <bold>Results:</bold> Eight subjects completed both challenges. Mean Total Nasal Symptom Score (TNSS) was higher in the Mobile NEC for most of the 2-hour duration (p<0.001); however, TNSS averaged over the last 30 minutes was not (paired t-test, p=0.16; mean (SE) 6.1 (1.2) and 4.5 (0.6), Mobile and Fixed NEC , respectively). Although there was no difference in FEV₁ between the two challenges (p=0.52), respiratory symptom scores were higher in the Mobile NEC over the last 60 minutes of the exposure (p=0.002). There was no difference in average Fel d 1 concentrations between the chambers (Mobile: 55; Fixed: 54 ng/m³). <bold>Conclusions:</bold> The Mobile NEC offers comparable cat-allergen exposure and nasal and respiratory responses to the Fixed NEC. Its portability facilitates expansion to multi-site chamber studies for clinical validation of allergy therapies. Future work could expand its capabilities to other aeroallergens.