Associations between inflammatory cytokines and organ damage in pediatric patients with hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a potentially fatal disease characterized by overwhelming inflammation response and multiple organ damage. Most of the clinical and laboratory manifestations of HLH are thought to be related to hypercytokinemia and organ infiltration with lymphocytes and histiocytes. The aim of this study was to investigate the associations between cytokines and various manifestations of HLH. A total of 105 patients diagnosed with HLH were enrolled in this retrospective study. The information including the patients' demographic characteristics, clinical and laboratory findings at presentation and cytokine data were collected. The median age at diagnosis was 2.8 years, with 74 patients (70.4%) documented Epstein-Barr virus infection. Hepatomegaly (88.6%), splenomegaly (81.9%), cytopenia (68.6%), elevated ferritin level (93.3%), hypofibrinogenemia (61.9%) and hemophagocytosis (77.3%) were found in more than half of the patients. Interleukin (IL)-6, IL-10 and interferon (IFN)-γ were found to be moderately or significantly elevated in most patients. In the correlation analysis, IFN-γ was closely related to the concentration of alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, lactate dehydrase (LDH), triglyceride and fibrinogen, while IL-10 was associated with platelet count. When split the patients into two groups according to the cytokine levels, patients with high IFN-γ presented higher level of ALT, AST, bilirubin, LDH, triglyceride, and fibrinogen, while patients with high IL-10 presented much lower hemoglobin and platelet count. In conclusion, the present study put forward clinical evidence that hypercytokinemia is related to organ damage in HLH. IFN-γ may contribute to liver impairment and coagulation disease, while IL-10 is a cytokine related to cytopenias.