Allergic Inflammation Modulation by IL-33

Mice were sensitized and challenged using a previously described protocol known to induce mast cell-dependent allergic inflammation^{22 (link)}. To study the effects of IL-33, the protocol was modified by introducing intranasal IL-33 instillations to sensitized mice before each antigen challenge. Mice were sensitized via i.p. injections with 10 µg/dose OVA (grade V; Sigma-Aldrich) in 100 µL saline or sham-sensitized with the equivalent volume of saline alone on days 0, 2, 4, 6, 8, 10 and 12 (Fig. 1a). The mice were then challenged with 200 µg/dose OVA in 20 µL PBS or PBS alone via i.n. instillation on days 39, 42 and 45. IL-33 (eBioscience, San Diego, CA, USA) (0.2 µg of IL-33 in 20 µL PBS) or PBS alone were given, before each OVA-challenge, via i.n. instillation on days 37, 38, 41 and 44. Lung mechanics measurements and tissue collection were performed 24 hours following the final OVA challenge.