Interleukin-17 (IL-17) is a group of cytokines, which are proteins that play a crucial role in the immune system. It is primarily produced by a type of immune cell called T helper 17 (Th17) cells. IL-17 helps to coordinate the body's defense against infections, particularly by promoting inflammation and recruiting other immune cells to sites of infection. In addition to its protective role, IL-17 is also involved in various inflammatory diseases, such as psoriasis and rheumatoid arthritis. Elevated levels of IL-17 can contribute to chronic inflammation and tissue damage, making it a target for therapeutic interventions in these conditions.