Given that the effects of this interleukin play a role in several lines of cells’ activation, IL-33 is involved in many different pathological conditions, such as cardiovascular diseases, arthritis, infective diseases, neurological conditions, allergic diseases, cutaneous conditions, and cancer, acting together with the neuropeptide substance P in inducing TNF-α in cultured MCs and enhancing the gene expression of mitogen-activated protein kinase (MAPK) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), well-known factors involved in inflammatory pathways [16]. This evidence concerns the gene IL33 and allergic disease.