PDCD1 and skin disorder: For instance, PD-1 signal blockade-induced psoriasis-like dermatitis is characterized by a prominent epidermal infiltration of CD8+ T cells and overexpression of IL-6, IL-23 and IL-17A cytokines, as demonstrated in a murine model of psoriasis induced by imiquimod (IMQ), carried out with genetically modified mice lacking PD-1 in CD8+ T cells (8).