IL2 and allergic disease: An important issue that needs to be emphasized considering in vitro tests is the fact that cytokines are determined in various conditions and various diseases [50]; however, only certain cytokines (i.e., TNF-α, IL-2, IL-4, IL-5, IL-6, IL-10, IL-13, and IFN-γ) are important in allergic reactions [51–56].