Interleukin 17A, IL-22, and IL-19 are elevated in both active skin lesions and blood in psoriasis and have been associated with disease activity.18,23,24 Ustekinumab inhibits secretion of IL-17A and other cytokines in vitro,25 but ex vivo studies from clinical trial specimens have been limited by assay detection limits for low abundant serum proteins. Here, IL19 is linked to psoriasis.