Summary During the last decade, the  eld of T cell immunology started to confuse the scienti c community. More and more subtypes of T helper cells and their counter-parts in the innateimmune system are described. We are just at the beginning to understand which speci c function the distinct subtypes ful ll.  22 cells are terminally di erentiated and very specialized T hel-per cells characterized by the secretion of their sig-nature cytokine IL-22 and lack of IL-4, IL-17 and IFN-γ.  e main function of  22 cells is to protect epithelial barrier organs such as skin and lung, but also to modulate in amed and injured tissue.  is review summarizes our current knowledge on  22 cells and their function in allergic disease.