Interleukin-23 (IL-23) is a cytokine, a type of protein that plays a crucial role in the immune system. It is primarily produced by dendritic cells and macrophages and is involved in the inflammatory response. IL-23 helps regulate the activity of T-helper 17 (Th17) cells, which are important for fighting infections and maintaining immune balance. IL-23 is linked to various autoimmune diseases, such as psoriasis and Crohn's disease, where it can contribute to excessive inflammation. Targeting IL-23 with specific therapies has become a focus in treating these conditions, aiming to reduce inflammation and improve patient outcomes.