Nevertheless, these findings add to the previous data demonstrating that IL-33 acts via ST2 to increase mast cell surface IgE, and to trigger histamine release and systemic anaphylaxis in naïve mice (38) and that poly I:C activates mast cells via TLR3, which may result in the recruitment of CD8+ cells (39). This evidence concerns the gene IL1RL1 and anaphylaxis.