Interleukin-10 (IL-10) is a cytokine, a type of protein that plays a crucial role in regulating the immune system. It is primarily produced by T cells, B cells, and macrophages, and its main function is to inhibit inflammatory responses. By doing so, IL-10 helps to maintain immune balance and prevent excessive tissue damage during infections or autoimmune diseases. IL-10 is also important in promoting the survival and growth of certain immune cells, which can enhance the body's ability to fight infections. Researchers are studying IL-10 for its potential therapeutic applications in conditions like inflammatory bowel disease and rheumatoid arthritis, where controlling inflammation is essential for patient health.