This type of asthma is called Type 2 (T2) asthma because it is orchestrated by Th2 lymphocytes that secrete a series of interleukins such as IL-4, −5, −9, and −13, which cause activation and recruitment of eosinophils, as well as the generation of IgE by B lymphocytes (Figure 3) (Barnes, 2017). Here, IL4 is linked to asthma.