IL6 and hemophagocytic syndrome: In addition, a subset of patients with PCGDTLs eventually developed hemophagocytic lymphohistiocytosis (HLH), a potentially fatal inflammatory syndrome characterized by overproduction of inflammatory cytokines, such as tumor necrosis factor α (TNF-α), IFN-γ, interleukin-1 (IL-1), and interleukin-6 (IL-6)25,26.