ABSTRACT
Autoimmune hepatitis (AIH) is a rare disease with an estimated prevalence of 170 cases per 1 million in the Northern European Caucasian population (1). The disease is characterized by a female predominance, hypergammaglobulinemia (>30 g/1), association with particular human leukocyte antigens (HLA) (DR3, DR4 in AIH type 1) and circulating antibodies against tissue antigens (2,3). At the time of diagnosis, the disease often has been present for several months and patients show high levels of serum transaminases. However, in 40% of patients, acute or even fulminant onset of hepatitis is found that may be mistaken for acute viral hepatitis (4). Histology usually reveals periportal and/or periseptal hepatitis (piecemeal necrosis) and lymphocytic infiltrates (5). The disease progresses further to bridging necrosis, panlobular and multilobular necrosis and active cirrhosis. Without treatment, up to 50% of patients with severe AIH will die within five years (6-10). The diagnosis of AIH is based on an array of clinical, serological and immunological features typical for hepatitis and exclusion of patients with other causes of liver disease (Table 1). These features are summarized in a provisional scoring system for the diagnosis of AIH (Table 1) (11). According to the autoantibodies found in AIH, it was proposed to classify AIH into subtypes 1-3 (AIH 13) (12) (Table 2). According to this nomenclature, AIH type 1 is characterized by antinuclear and/or anti-smooth muscle autoantibodies (13,14), AIH type 2 by antibodies specific for liver and kidney microsomes (LKM) (15) and/or liver cytosolic protein type 1 (anti-LCl) (16) and AIH type 3 by autoantibodies against anti-soluble liver antigen (antiSLA) (17) or antibodies to liver-pancrease antigen (antiLP) (18). Other autoantibodies associated with AIH are directed against the asialoglycoprotein receptor (ASGP-R) (19) and neutrophil cytoplasmic antigens (ANCA) (20).
