Additional Study Information: TReatment for ImmUne Mediated PathopHysiology (TRIUMPH) is a multi-center, three-arm clinical trial of immunosuppressive therapy for children with acute liver failure. This is a double-blind study, so the study doctors and participants will not know to which arm the participants are assigned. The study will determine if corticosteroids or equine anti-thymocyte globulin therapy improves survival for children with this rare, life-threatening condition, as compared to supportive care. Participants will be enrolled while they are hospitalized for acute liver failure, and will continue to be followed for approximately one year. If you have any questions regarding this study, please contact the Transplant Clinical Research Center (TCRC).