The AOSD group had significantly higher serum IL-18 levels (p<0.0001), absolute neutrophil count (ANC) (p<0.0001) and Fib (p=0.0023), and lower sIL-2R levels (p<0.0001), HScore (p< 0.0001) and Trig (p=0.031) compared to the adult HLH group. Here, IL18 is linked to adult-onset Still disease.