IL4 and allergic disease: The immune pathogenesis of allergic diseases is strictly related to disorders of homeostasis associated with Th2 cells, which produce proallergic cytokines, such as interleukin 4 (IL-4), IL-5, and IL-13, and Th1 cells, which produce proinflammatory cytokines: IL-12, IL-18, interferon gamma, and tumour necrosis factor [12].