Both A) IL-33 and B) MPO were measured using ELISA. In the sham control, mast cell deficient mice expressed a modestly higher level of IL-33, but did not exhibit as strong of a response as the wild type mice to LL-37 challenge. After LL-37 exposure, wild type mice demonstrated similar levels of IL-33 to C-kit (−/−) mice. For MPO activity, the wild type mice produced higher levels of MPO when compared to C-kit (−/−) mice after the administration of LL-37. The plot is of the mean ± standard deviation. *, **, and *** indicate P-values of <0.05, <0.01 and <0.001, respectively.