Finally, after observing a strong similarity between immune-mediated GF and hemophagocytic lymphohistiocytosis (HLH), we treated with Emapalumab, an anti-IFNγ mAb (5), on a compassionate use basis, three patients with primary HLH who, after having experienced GF, underwent a second successful HSCT. Here, IFNG is linked to hemophagocytic syndrome.