Interleukin-2 (IL-2) is a type of protein known as a cytokine, which plays a crucial role in the immune system. It is primarily produced by T cells, a type of white blood cell, and helps regulate the growth, development, and activity of other immune cells. IL-2 is essential for the proliferation of T cells and B cells, which are vital for the body's defense against infections and diseases. IL-2 is also significant in medical treatments, particularly in immunotherapy for certain cancers. By enhancing the immune response, IL-2 can help the body recognize and attack cancer cells more effectively. Researchers are exploring its potential in treating autoimmune diseases and enhancing vaccine responses as well.