Interleukin-7 (IL-7), also known as lymphopoietin 1 and pre-B cell factor, is a hematopoietic growth factor belonging to the IL-7/IL-9 family. It is produced by keratinocytes, dendritic cells, hepatocytes, neurons and epithelial cells. IL-7 binds and signals through IL-7 receptor, a heterodimer consisting of IL-7 receptor alpha and common gamma chain receptor. IL-7 plays a role in regulating early B cell and T cell development. It is also important for optimal dendritic cell-T cell interaction.