Important laboratory characteristics of AOSD are leukocytosis with predominance of neutrophils and the increase of proinflammatory cytokines, including IL-1β, IL-6, IL-18, TNF-α, and IFNγ, but with negative testing for rheumatoid factor (RF) and autoantibodies [14, 22, 23]. This evidence concerns the gene IL18 and adult-onset Still disease.