IL4 and asthma: It has been confirmed that IL-12 as a Th1 cytokines was a protective cytokine in asthma, which could promote the differentiation of Th1 cells and the production of IFN-γ, inhibit Th2 cells to secrete IL-4, IL-5 and IL-13, impact the differentiation of B cell, and inhibit the infiltration of eosinophil in airway [39].