Interleukin-17F (IL-17F) is a cytokine, a type of signaling molecule in the immune system. It is produced by a subset of immune cells known as T helper 17 (Th17) cells. IL-17F plays a crucial role in the body's defense against infections and is involved in inflammatory responses. This cytokine is closely related to another cytokine called Interleukin-17A (IL-17A). Both IL-17F and IL-17A can promote inflammation and are implicated in various autoimmune diseases, such as rheumatoid arthritis and psoriasis. Understanding IL-17F's functions can help in developing targeted therapies for these conditions.