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 are the precursors to all 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 the production of white blood cells, which are essential for fighting infections and maintaining overall health. Dysregulation of IL-3 can contribute to various diseases, including certain types of cancer and autoimmune disorders.