IL-7 and IL-15: therapeutic cytokines for immunodeficiency.

Immunodeficiency due to inborn errors, infections, autoimmune diseases and the toxicity of certain therapies, has become an important clinical challenge. Strategies to enhance immune function could improve the outcome for a considerable number of patients. Although myeloid growth factors have found widespread use in clinical medicine, a 'lymphoid growth factor' has not yet been established in clinical use. Several recent studies have proposed two candidate immunostimulatory cytokines: interleukin-7 (IL-7) and IL-15. In this Review, we discuss recent findings regarding the effects of IL-7 and IL-15 on lymphopoiesis and their potential use for the treatment of immunodeficiency.