ABSTRACT FINAL ID: 1652
TITLE: The Clinical Significance of IgG4 Positive Autoimmune Hepatitis
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Background: Little is known about the significance of IgG4+ plasma cells in autoimmune hepatitis (AIH). IgG4+ plasma cells (≥ 5/high powered field [HPF]) were recently associated with a robust steroid response in an Asian cohort, yet US data is lacking.
Aim: Analyze IgG4+ plasma cells in liver biopsies from a US AIH cohort to determine if this sub-group has a unique clinical presentation and response to immunosuppression.
Methods: Biopsies and records of clinically confirmed AIH patients from a single tertiary care center were analyzed. Patient characteristics, laboratory data, mean daily immunosuppressant doses, time to remission, and number of relapses within one year of presentation were recorded. Liver biopsies were stained with IgG4 and the total and highest density of IgG4+ plasma cells recorded by an expert liver pathologist.
Results: Forty-nine patients with clinically and biopsy confirmed AIH were studied. Mean age and total IgG4+ count were 43.51 years (SD 2.51) and 8.51 (SD 1.98), respectively, with a mean density of 2.83/HPF (SD 0.60). Upon stratification by IgG4 density, ALT (295.29 vs 1350.08 U/L) and bilirubin (2.78 vs 13.56 mg/dL) at presentation were significantly higher in patients with ≥ 5 IgG4/HPF (p<0.001 and p<0.001, respectively, Table). Furthermore, the mean effective prednisone dose was increased in the ≥ 5 IgG4/HPF group and approached statistical significance (p=0.058). Average time to remission was not different between groups (p=0.881).
Conclusions: AIH patients with ≥5 IgG4 cells/HPF on diagnostic liver biopsy presented with significantly higher ALT and bilirubin, with a trend for higher steroid doses over time. This suggests a relationship of IgG4+ cells to acute AIH presentation and also immunosuppression requirements, in contrast to Asian reports. Further studies are warranted in our population to interrogate whether ≥5 IgG4/HPF in AIH is indicative of IgG4 related systemic disease rather than a defined subset of AIH.