Recombinant human IL-23 expressed in engineered human cells. IL-23 is a 55 kDa heterodimeric cytokine composed of two disulfide-linked subunits, a p19 and a p40 subunit and belongs to the IL -6/IL-12 protein family. The biological activity of IL-23 has similarities to IL-12 such as the induction of proliferation IFN-γ, and the effects of IL-23 are restricted to memory T-cells. IL-23 promotes production of pro-inflammatory cytokines and acts in concert with IL-17 to promote an acute response to infection in peripheral tissues. IL-23 binds to a heterodimeric receptor complex and activates the Jak-Stat signaling cascade.