IL-31 produced by activated Th2-type T cells，cooperates with a heterodimeric receptor consisting of IL-31 Receptor Anatagonist and Onconstatin-M Receptor that is continuesly expressed on epithelial cells and keratinocytes. IL-31 plays a role in the promotion of allergic skin disorders and in regulating other allergic diseases，such as asthma. IL-31 is involved in the itching sensation and endorses the scratching behavior in NC/Nga mice with atopic dermatitis. IL-31 expression is connectd with CLA（+） T cells and contributes to the development of atopic dermatitis-induced skin inflammation and pruritus. IL-31 is a powerful inducer of proinflammatory mediators in human colonic SEMFs. IL-31 takes part as a proinflammatory cytokine derived from Th2 cells.
Serum IL-31 level is higher in patients with atopic dermatitis. IL-31 is involved in a broad range of immune- & non-immune cells & possesses potential pleiotropic physiological functions，including regulating hematopoiesis & immune response，causing inflammatory bowel disease，airway hypersensitivity & dermatitis.
