Larson D, Patel P, Salapatek AM, et al. - In this study with 24 participants, the goal was to perform a comparison of clinical as well as immunologic responses to cat allergen in nasal allergen challenge (NAC) vs environmental exposure chamber (EEC). The participants were randomly assigned to receive either NAC followed by a 2-day challenge in an EEC or a 2-day challenge in an EEC followed by NAC. The total nasal symptom score area under the curve for the first 3 hours following allergen exposure in NAC or following the start of exposure in EEC was the primary outcome. Experts noted that both challenges raised IL-5 and IL-13 in nasal fluids and serum as well as caused changed nasal cell expression of gene modules associated with mucosal biology and transcriptional regulation. Significant links with total nasal symptom score and peak nasal inspiratory flow were demonstrated by alterations in gene modules, more so than cytokine measurements. EEC exposure vs NAC produced larger responses and more early terminations. Findings revealed temporally different and nonequivalent in magnitude clinical outcomes of NAC and EEC, but the observed immunologic responses were similar. Relying the selection of a specific allergen challenge method on considerations of study goals and cost was recommended.