IL-23 is a proinflammatory, heterodimeric protein composed of two subunits: a unique p19 subunit, and a p40 subunit that is shared with IL-12. IL-23 is secreted by activated dendritic cells and macrophages, and signals though a receptor comprised of IL-23R complexed with IL-12Rbeta1. IL-23 has been shown to enhance proliferation of memory T cells. It also stimulates the production of IFN-gamma in NK cells, induces IL-17 production, and drives Th17-mediated responses. Recombinant Human IL-23 is a 53.5 kDa, heterodimeric protein consisting of the two subunits, p19 (170 amino acids) and p40 (306 amino acids).