Chronic autoimmune diseases, on the contrary, are characterized by a direct correlation between the levels of IL-15 and IL-17, as was shown for idiopathic inflammatory myopathies, rheumatoid arthritis (concomitant with an increase in the levels of IL-18), and multiple sclerosis [57,68,69], as well as in the wide range of autoimmune and systemic diseases associated with HIV-1 infection [70,71,72]. Here, IL18 is linked to rheumatoid arthritis.