(A) Serum sCD25 levels in patients with SCID/CID, FHL, I-HLH (infection triggered “secondary” HLH), and CGD. (B) Serum ferritin levels in SCID/CID, FHL, I-HLH, and CGD patients. (C) Ratio of ferritin/sCD25 in SCID/CID, FHL, I-HLH, and CGD patients. *P<0.05. **P<0.01. The dotted line indicates the cut-off value according to the HLH diagnostic criteria. The bars indicate means ± standard deviation.