Interleukin 31 (IL-31) is a 15.65 kDa cytokine with 141 amino acid residues. IL-31 is mainly secreted from Th2 cells and binds to a receptor called IL-31RA. Upon binding to IL-31RA, IL-31 activates several signal pathways like MAPK, PI3K/AKT, and Jak/STAT pathways. It is critical in regulating many biological functions, such as cell proliferation, hematopoiesis, induction of cytokines, inflammation, and immune response. It also responds to an antigen by facilitating cell-mediated immunity.
