IL4 and hemophagocytic syndrome: AUCs of IL-4, IFN-γ, IL-10, TNF-α, IL-2, and IL-6 levels were calculated to be 0.841, 0.799, 0.506, 0.494, 0.457, and 0.250, respectively, indicating that levels of IL-4 and IFN-γ may be used as additional tools for the quick differential diagnosis between primary and secondary HLH (Fig. 2).