A chronic inflammatory disorder of unknown etiology affecting the liver; characterized by periportal necrosis (interface hepatitis or piecemeal necrosis), hypergammaglobulinemia, and autoantibody formation
- Can be asymptomatic or lead to acute hepatic failure
- Diagnosis of autoimmune hepatitis (AIH) is based on clinical, histologic, biochemical, and immunologic criteria.
0.1 to 2/100,000 per year in Caucasians. Highest incidence in Northern Europeans; lower in Japanese
- 11 to 17/100,000 in Europe
- Female > male (type I: 4:1; type II: 10:1)
- Bimodal age distribution for type I: Adolescents and adults in the 4th to 6th decades are most at risk.
- Type II is more common in Southern Europe; primarily affects young females and children
Etiology and Pathophysiology
- Hepatic damage is cell mediated.
- Human leukocyte antigen (HLA) engages antigen-processing cells to stimulate cytotoxic T-cell response.
- Cytotoxic T lymphocytes infiltrate hepatic tissue, releasing cytokines and damaging hepatocytes.
- Chronic hepatic inflammation leads to fibrosis and cirrhosis in advanced cases.
- Fulminant inflammation can lead to acute liver failure without cirrhosis.
- Type I (80% of cases): circulating anti–smooth muscle antibodies (ASMAs) and/or antinuclear antibodies (ANAs)
- Type II: antibodies to liver/kidney microsome type I (anti-LKM-1)
- Type III (least understood): soluble liver antigen/liver pancreas antigen (SLA/LP); clinically similar to type I but with different antibody profile
Associated with HLA haplotypes DR3, DR4 in white Northern Europeans (1)
- Triggers include medications and viruses (herpes simplex, acute hepatitis A or B, Epstein-Barr, cytomegalovirus).
- Associated autoimmune conditions
Commonly Associated Conditions
- Type 1 diabetes mellitus
- Autoimmune thyroiditis
- Immune-mediated hemolytic anemia
- Idiopathic thrombocytopenic purpura
- Celiac sprue; ulcerative colitis
- Rheumatoid arthritis, vitiligo
- Primary biliary cirrhosis and primary sclerosing cholangitis occasionally overlap with AIH (1).
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