IBD is associated with a Th1/Th17 T cell-mediated response induced by interleukin-12 (IL-12) and IL-23, with concomitant increased production of IL-2, IL-17, IL-18, and IFN-γ (132, 133), whereas asthma and allergic diseases are associated with a typical T helper type 2 (Th2)-mediated response characterized by the production of interleukin-4 (IL-4), IL-5, and IL-13 (134). This evidence concerns the gene IL4 and asthma.