A. Effect of blocking IL-33 or ST2 on pulmonary responses to Lys-ASA challenge. Ptges−/− mice were challenged with Lys-ASA by inhalation 24 h after the last of 6 intranasal doses of Df. RL was monitored continuously for 45 min and the peak change from baseline was recorded for each mouse. The indicated groups received single intraperitoneal doses of rat anti-mouse IL-33, IgG isotype control, recombinant ST2-Fc fusion protein, or Fc control. B. Levels of BAL fluid mMCP-1, histamine, and PGD2 in BAL fluids from the same mice. Results are from 10 mice/group in two separate experiments. * p<0.05, ** p<0.01, *** p<0.001.