IL22 and psoriasis: Previous researchs have revealed that CD8+ T cells infiltrate the skin lesions and blood of psoriasis patients and CD8+ T cells can produce IFN-γ, IL-17 and IL-22 (Hijnen et al., 2013), suggesting that CD8+ T cells play an important role in the development of psoriasis, but their role in psoriasis has not yet been fully elucidated, and very few studies have explored the specific subtypes and corresponding functions of CD8+ T cells.