TNF and Hemophagocytosis: Identification of high levels of selected cytokines provided a likely explanation for some clinical features: fever is induced by IL-1 and IL-6; pancytopenia results from high levels of IFN-γ and TNF-α and also from hemophagocytosis; hypertriglyceridemia results from the inhibition of lipoprotein lipase by TNF-α; ferritin is secreted by activated macrophages, also responsible for the high levels of plasminogen activator, which cause high plasmin levels and hyperfibrinolysis.