Targeting IL-18 with IL-18BP is thus a rationale mechanism to reduce IFN-γ in HLH since we have observed that IL-18BP concentrations are inadequately elevated in S-HLH patients in comparison with increased IL-18, leading to large excess of free IL-18 which induces IFN-γ (Dinarello and Kaplanski, 2005; Mazodier et al., 2005). The gene discussed is IL18BP; the disease is hemophagocytic syndrome.