The major difference between lesional skin samples from AD and psoriasis is that psoriasis plaques contain mainly cytokines secreted from Th1 and Th17 cells, for example, γ-interferon and IL-17, whereas AD skin samples contain relatively higher numbers of cytokines secreted from Th2 and Th22 cells (1, 2, 31). Here, IL17A is linked to psoriasis.