IL17A and psoriasis: Consistently with a prevalence of adaptive immunity over innate immune responses in psoriasis induced by anti-PD-1 therapy, we found that the mRNA expression levels of psoriasis-related cytokines, such as IL-17A, IL-23, IFN-γ and IL-22 were significantly higher in the skin of the three patients, as compared to psoriasis-like reactions to anti-TNF-α, and similar to mRNA levels detected in chronic psoriasis plaques (Figure 4A).