The functions of IL-18 in the brain are also peculiar, since the cytokine is active (inflammation and homeostasis) even in the absence of its receptor IL-1R5, while IL-1R5 seems to be involved in the pathogenesis of experimental allergic encephalomyelitis (EAE, the mouse model of multiple sclerosis) in the absence of its IL-18 ligand (21, 22). Here, IL18 is linked to multiple sclerosis.