NB-UVB treatment suppresses serum levels of psoriasis-driving cytokines, such as tumor necrosis factor (TNF)-α, IL-8, IL-12, IL-17, IL-22, IL-23, and IL-34 and elevates the levels of IL-10, an anti-inflammatory cytokine, in patients with psoriasis14,15. Here, IL17A is linked to psoriasis.