The inflammatory response in psoriasis is mainly driven by T cells, especially T helper cells (Th17), and is mediated by different cytokines, especially TNF-α, IL-17, IL-23 but also other cytokines such as IFN-γ, IL-2, IL-6, IL-8, IL-17, IL-18 and IL-22. This evidence concerns the gene IL22 and psoriasis.