Intestinal IL-33 promotes platelet (PLT) function for hemostasis. (A) Time to cessation of bleeding in response to tail injury between Il33fl/fl and Vil1creIl33fl/fl mice. (B) PLT counts between Il33fl/fl and Vil1creIl33fl/fl mice. (C) Relative 5-HT levels in serum were assessed by ELISA between Il33fl/fl and Vil1creIl33fl/fl mice. (D) Representative histograms of fluorescence intensity of CD62P and Jon/A for PLTs treated with or without thrombin between Il33fl/fl and Vil1creIl33fl/fl mice. (E) Quantification of geometric mean fluorescence intensity (MFI) in panel D. (F) Time to cessation of bleeding in response to tail injury between Il1rl1fl/fl and ChgacreERIl1rl1fl/fl mice. (G) PLT counts between Il1rl1fl/fl and ChgacreERIl1rl1fl/fl mice. (H) Relative 5-HT levels in serum were assessed by ELISA between Il1rl1fl/fl and ChgacreERIl1rl1fl/fl mice. (I) Representative histograms of fluorescence intensity of CD62P and Jon/A for PLTs treated with or without thrombin between Il1rl1fl/fl and ChgacreERIl1rl1fl/fl mice. (J) Quantification of geometric MFI in panel I. Data are representative of 2 independent experiments (D,I) or are pooled from 2 independent experiments (A-C, E-H, J). *P < .05, **P < .01, ***P < .001 by Student t test. Error bars represent standard deviation.