IFNG and adult-onset Still disease: Incubation of a macrophage cell line with serum samples from patients with active AOSD results in the induction of IFNγ production, indicating the levels of IL-18 in the serum are sufficient to induce IFNγ production and can be reversed through administration of IL-18 binding protein (BP), an endogenous regulator of IL-18 [71, 72].