Murine Allergen Sensitization and Exposure

The experimental allergen sensitization and exposure model utilized in this study has been previously described in detail [13 (link)] and is summarized in Fig 1. Briefly, mice were sensitized twice (Day 1 and Day 6) intraperitoneally (i.p.) with 8 μg chicken ovalbumin (OVA, Sigma-Aldrich, St Louis, MO, USA) bound to 4 mg aluminum hydroxide (Sigma-Aldrich) in phosphate buffered saline (PBS). On Day 14, mice were briefly anesthetized using isoFlurane (Flurane^®, Baxter, Deerfield, Ill, USA) and split in two groups; the exposure (OVA/OVA) received an intranasal (i.n.) administration of 100 μg OVA in 25 μl of PBS on five consecutive days, while the control (OVA/PBS) group received only PBS. In another set of experiments designed to evaluate the role of BAFF, OVA sensitized mice received i.n. instillations of BAFF-R-Ig fusion chimeric protein (7 μg; R&D Systems, Abingdon, UK), which binds to its receptor (BAFFR) and blocks its action [14 (link)], or its control protein, one hour prior to OVA exposure on five consecutive days, as indicated by green arrows (Fig 1).