Type 1 AIH (80% of cases): characteristic autoantibodies include antinuclear antibodies (ANAs), anti-smooth muscle antibodies (ASMAs) anti-soluble liver antigen antibodies (anti-SLA)
Type 2 AIH: characteristic autoantibodies include anti-liver-kidney microsomal-1 antibodies (anti-LKM-1), anti-liver cytosol antibodies-1 (ALC-1)
Clinical features
Nonspecific symptoms
Fatigue
Upper abdominal pain
Weight loss
Signs of acute liver failure (∼ ⅓ of patients)
Diagnostics
Laboratory tests
Liver chemistries: ↑↑↑ ALT and ↑↑ AST, ↑ GGT, normal or ↑ ALP, and ↑ bilirubin
Serum antibodies
ANA, ASMA: combination is highly specific for type 1 AIH
Anti-LKM-1: typically positive in type 2 AIH
SPEP: hypergammaglobulinemia (↑ IgG)
Liver biopsy
Histological findings:
Lymphoplasmacytic interface hepatitis: ongoing inflammatory process with lymphocytic infiltration, bridging or multiacinar necrosis, and fibrotic changes
Bile duct changes (e.g., cholangitis, ductal injury)
