[Current concepts on the physiopathology of adult-onset Still's disease].

PURPOSE: Adult-onset Still's disease (AOSD) is a rare systemic inflammatory disorder of unknown origin. It is characterized by hectic fever, evanescent rash, polyarthralgias or polyarthritis, sore throat, hepatosplenomegaly, lymphadenopathy, polynuclear leukocytosis, liver cytolysis, and high serum level of ferritin with low glycosylated fraction. CURRENT KNOWLEDGE AND KEY POINTS: An increased serum level of ferritin, IL-8, IL-6, IL-18 and TNF-alpha indicates that macrophages are highly activated in AOSD. Interleukin 18 (IL-18) seems to be a key cytokine in the pathogenesis of AOSD. Serum IL-18 levels are increased in AOSD patients compared to other systemic inflammatory diseases such as rheumatoid arthritis and they are well correlated with serum ferritin levels and disease activity. IL-18 could cause acute liver injury and arthritis. Macrophages could be activated by infectious agents such as viruses and by an inadequate control of T cell response secondary to depressed Natural Killer lymphocyte function, similarly to that observed in systemic juvenile idiopathic arthritis. Sustained macrophage activation can lead to the hemophagocytic syndrome, a severe complication of both AOSD and systemic juvenile idiopathic arthritis. FUTURE PROSPECTS: Cytotoxic cell functions should be probably studied in AOSD as they were in the hemophagocytic syndrome and systemic juvenile idiopathic arthritis because AOSD, characterised by a marked macrophage activation may be related to an immunological deficiency.