Belimumab in Autoimmune Hepatitis

Inclusion Criteria: * Ability to provide written informed consent * Established clinical diagnosis of autoimmune hepatitis for at least 6 months * Participant and clinician consent to follow AIH study therapy guidance for the duration of the open label clinical trial. Group A: * ALT \> 1.5 x ULN in the absence of clinical evidence or concern for alternative etiology, and assessed by the investigator as related to active AIH using standard of care evaluation. * Ongoing therapy with corticosteroids, and/or non-biologic immunosuppressants (AZA, MMF, MP) at a stable dosage for 4 weeks prior to screening Group B: * Patients with normal ALT and normal IgG concentration * Ongoing therapy with single agent immunosuppression or immunosuppression with low dose Prednisone (10mg or less or budesonide 6mg or less)) alongside a second line agent (azathioprine, MMF, MP) * Fibroscan showing liver stiffness of \< 16kPa. Exclusion Criteria: * Primary liver disease other than AIH * High probability of NAFLD as assessed by the investigator. * ALT \>15 x ULN * Patients positive for HBsAg or HBcAb and/or Hepatitis C RNA * Prior use if corticosteroid \>15mg daily * A positive pregnancy test and/or breast feeding * The presence of advanced liver disease as defined by any of: 1. Total Bilirubin \>3 x ULN. 2. Platelet count \<100 x109/L. 3. INR \>1.5 * Live vaccines within 30 days prior to screening or at any time during the study * The use of other biologics including TNF inhibitors, abatacept, or tocilizumab within the washout period