IL17A and psoriasis: Recently, two studies suggested that a dermal DC subset may be involved in psoriasis initiation via the production of IL-23 (Wohn et al, 2013), a key cytokine that mediates expansion of IL-17- and IL-22-producing cells, promoting important events in psoriasis pathology, including neutrophil infiltration and epidermal thickening (Di Cesare et al, 2009).