- Treatment that uses cytokines (substances made by immune cells) to help the body fight cancer, infection, or other diseases. Cytokines play an important role in the body’s immune response. They can also be made in the laboratory to use as treatment for different diseases. In cancer, cytokine therapy may help the immune system kill cancer cells or keep them from growing. The two main types of cytokines used to treat cancer are interleukins and interferons.