IL2 and Hypofibrinogenemia: The diagnostic criteria for HLH requires five of eight of the following: fever, splenomegaly, cytopenias affecting greater than two of three lineages, hypertriglyceridemia and/or hypofibrinogenemia, hemophagocytosis in the bone marrow, spleen or lymph nodes in the absence of malignancy, low or no NK cell activity, ferritin greater than 500 μg/L and a soluble IL-2 (sCD25) greater than 2400 U/mL (34).