Rabbit anti Human IL-23 antibody recognizes the N-terminal (NT) domain of human interleukin-23 (IL-23), a ~21 kDa heterodimeric cytokine structurally related to IL-12. IL-23 is composed of a p19 subunit encoded by the IL23A gene, and a p40 subunit of interleukin-12 (IL12B). IL-23 is expressed mainly by activated macrophages and dendritic cells, and plays an important role in bridging innate and adaptive responses. IL-23 activates a subset of T cells called Th17 cells, which are characterised by the production of interleukin-17. The IL-23/IL-17 pathway is essential for the induction and maintenance of brain and joint inflammatory autoimmune diseases, including Guillain Barre Syndrome, Multiple sclerosis and rheumatoid arthritis.