As was the case with IL-17Apos CD8 T cells, also the percentage of IL-22pos CD8 T cells was much higher in the epidermis than in the adjacent dermis of psoriatic skin, but not in normal skin (Figure 4), underlining a possible role of IL-17A and IL-22 producing CD8 T cells in the pathogenesis of psoriasis. This evidence concerns the gene IL17A and psoriasis.