Th17 cells, as well as Th1 cells and keratinocytes, secrete TNF-α, IFN-γ, IL-1β, IL-6, IL-12, IL-17A, IL-22, IL-23 participating in pathophysiologic processes of psoriasis [5] and current biological therapies as T cell-directed agents have demonstrated excellent efficacy in psoriasis. Here, IL17A is linked to psoriasis.