IL4 and asthma: Stimulation of allergens can increase the release of cytokines such as IL-4, IL-5, and IL-13 in Th2 cells in the body, promote the differentiation, recruitment, and activation of EOS in airway mucosa, further release a large number of inflammatory mediators, promote the occurrence of endogenous eosinophilic inflammatory reaction, and finally, cause asthma.