Interleukin-3 (IL-3) is a type of cytokine, which is a protein that plays a crucial role in the immune system. It is produced by various immune cells, including T cells and mast cells, and helps regulate the growth and differentiation of blood cells. IL-3 is particularly important for the development of hematopoietic stem cells, which give rise to different types of blood cells, including red blood cells and white blood cells. IL-3 acts by binding to specific receptors on the surface of target cells, triggering a series of cellular responses. This cytokine is involved in various immune functions, such as promoting inflammation and enhancing the body's response to infections. Dysregulation of IL-3 can contribute to certain diseases, including allergies and leukemia.