IFNG and macrophage activation syndrome: Further, and exclusively for IFN-γ, we included measurements of plasma derived from patients with hemophagocytic lymphohistiocytosis (HLH) or macrophage activation syndrome (MAS), presenting with detectable IFN-γ concentrations in the majority (n = 5/7) of patients, with a median concentration of 16.64 pg/mL (Figure 4C).