Cerebral interleukin-15 shows upregulation and beneficial effects in experimental autoimmune encephalomyelitis

Interleukin (IL)-15 can cross the blood–brain barrier to act on its specific brain receptor (IL15Rα) and co-receptors. The important roles of neuronal IL15 and IL15Rα in experimental autoimmune encephalomeylitis (EAE) are suggested by the upregulation of IL15Rα mRNA in different regions of the brain and spinal cord, and by double-labeling immunohistochemistry showing neuronal localization of IL15 and IL15Rα in different neurons. Contrary to expectations, IL15 treatment lessened EAE severity. IL15 knockout mice showed heightened susceptibility to EAE with significantly higher scores that were decreased by treatment with IL15. Thus, IL15 improves this CNS autoimmune disorder as a potential therapeutic agent.