Human IL-31 plays a role in inflammation of the skin. It is preferentially produced by type 2 helper T cells. IL-31 signals via a receptor complex that is composed of IL-31 receptor A (IL31RA) and oncostatin M receptor subunits. These receptor subunits are expressed in activated monocytes and in unstimulated epithelial cells. Signaling also involves the JAK/STAT pathway, the PI3 kinase/AKT cascade, and the MAP kinase pathway.