The pleiotropic effects of interleukin 7 and their pathologic and therapeutic implications.

Interleukin-7 (IL-7) is a cytokine initially described as a growth factor for B cell progenitors. IL-7 also induces T cell proliferation and has pleiotropic effects. IL-7 enhances T-lymphocyte cytotoxicity, stimulates anti-tumoural properties of monocytes/macrophages, and induces tumour rejection in mice. It could thus be of interest in immunotherapy and may play a role in the generation of lymphoid neoplasia because leukaemic cells of B and T lineage express functional IL-7 receptors. Finally, IL-7 is, as IL-2, a cytokine of pivotal importance in the immune system, and so could be involved in abnormal immune response such as autoimmunity.