IL-33 signaling is required for neonatal RSV immunopathophysiology.

<p>(<b>a</b>) Number of Th1, Th2, and multifunctional mTh cells in the lungs of wild-type (WT) or ST2-deficient (<i>Il1rl1</i>^-/-) mice at 6 dpi following reinfection with RSV (methods) (<i>n</i> = 5–6 per group). (<b>b</b>) Change in airway resistance in response to increasing doses of inhaled methacholine after treatment as in <b>a</b> (<i>n</i> = 6 per group), compared to naïve control mice of similar size and age. (<b>c</b>) Total cells (Total), monocytes/macrophages (Mo/MΦ), lymphocytes (Lymph), neutrophils (Neutro), and eosinophils (Eos) in BAL fluid after treatment as in <b>a</b> (<i>n</i> = 5–8 per group). *<i>P</i> < 0.05 (Student’s <i>t</i>-test (<b>a</b>, <b>c</b>) or two-way ANOVA with Bonferroni post-hoc tests (<b>b</b>)). Data are representative of two independent experiments (means ± s.e.m).