Cytokines released by Th2 lymphocytes (IL-4, IL-5, and IL-13) stimulate, among others things, the proliferation of eosinophils that are subsequently recruited to the inflammatory foci from circulation, causing the eosinophilia characteristic of EoE, BA, and AD [32,33,34,35]. Here, IL4 is linked to eosinophilic esophagitis.