Serum expression of IL‐6, IL‐18, GROα associated with intrinsic immunity and neutrophils; IFN‐γ, TNF‐α associated with Th1; VEGF‐A associated with angiogenesis; IL‐17A associated with Th17; TARC, DEFB2, IL‐13 associated with Th2 were significantly higher than normal in patients with moderate to severe psoriasis (p < 0.05). Here, IL17A is linked to psoriasis.