Interleukin-7 (IL7) is a cytokine mportant for B and T cell development. IL7 plays an active role in the development,survival,maintaining and restoring homeostasis of mature T lymphocytes. It is also a key regulator of the commitment,survival,proliferation and maturation of B cells during development. Furthermore,IL7 can improve the antiviral function and expansion of natural killer (NK) cells and regulate the development and differentiation of dendritic cells. IL7 has also been reported as a regulator of the development of central nervous system and myogenesis and skeletal muscle cell migration.