Tumor necrosis factor-alpha (TNF-α) is a cytokine, a type of protein involved in cell signaling, primarily produced by macrophages. It plays a crucial role in the immune response by promoting inflammation and regulating immune cells. TNF-α helps the body fight infections and can also induce cell death in certain conditions. However, excessive levels of TNF-α are associated with various inflammatory diseases, such as rheumatoid arthritis and Crohn's disease. In these cases, TNF-α can contribute to tissue damage and chronic inflammation, leading to the development of therapies that target this cytokine to alleviate symptoms and improve patient outcomes.