Thus, this modulatory action of EGF and FGF21 could be interpreted as harmful, however, it is possible that it is a way to control the large amounts of Th1 and Th2 cytokines that activated NKT can produce, and may contribute, for example, to the development of IgE-mediated allergic asthma [64,65,66]. Here, FGF21 is linked to allergic asthma.