HMGB1 and Hepatosplenomegaly: When the association between HMGB1 serum levels and clinical characteristics of the disease was tested, we found that systemic JIA children with hepatosplenomegaly and serositis (27695,03 pg/ml) had significantly higher HMGB1 serum levels compared with patients without (12678,06 pg/ml) corresponding features (P < 0.001).