Table 1.
Main autoantibody markers of AIH with their corresponding target antigens, techniques of detection, and AIH clinical features (1, 3–8).
| Autoantibodies | Target antigen | Techniques of detection | AIH clinical features |
|---|---|---|---|
| Anti-smooth muscle antibodies (ASMA) | Filamentous actin | IIF – rodent stomach and kidney sections – reaction on stomach muscular layers, vessels, glomeruli, and fibrils of tubular cells (tubular pattern) | Ratio female: male – 4:1 Higher levels of γglobulins |
| AIH-1 (70%); frequently associated with anti-nuclear antibodies | |||
| The most common marker of AIH in all ages | HLA susceptibility DR3 and, North and South America countries with DR13 | ||
| Anti-actin antibodies | Filamentous actin | IIF – cell culture (human fibroblasts, HEp2 cells) | |
| ELISA (less specific); high reactivity in other liver diseases and even without ASMA reactivity | |||
| Anti-nuclear antibodies (ANA) | Histone, Ro (SSA) | IIF (homogeneous and speckled patterns) | Isolated ANA are more common in adults |
| 50–70% of patients with AIH-1, mainly in association with ASMA | Other patterns (nucleolar, centromere, nuclear dots, and nuclear envelope) are not related to AIH | Markers of a less aggressive disease Higher association with rheumatologic diseases | |
| ELISA (anti-histone and anti-Ro antibodies) | |||
| Relationship with HLA DR4; in Brazil there is no relationship between ANA reactivity and HLA DR | |||
| Anti-liver kidney microsome antibodies type 1 (anti-LKM1) 15% of patients with AIH 90% of patients with AIH-2 | Cytochrome CYPIID6 | IIF – liver and kidney tissue sections – homogeneous fluorescence in hepatocytes, and reactivity in proximal renal tubular cells | AIH-2 More frequently detected in young children, even younger than 5 years old; less commonly in patients older 20 years of age |
| Immunoblotting (mainly 50, 56, and 66 kDa) | Acute liver failure | ||
| Other techniques: immunodiffusion, ELISA, LIA | |||
| Relationship with class II HLA DR7 and DQ2 (Brazil and Canada); DR3 (Western Europe) | |||
| Relapses more frequent | |||
| Anti-liver cytosol type 1 | Formiminotransferase cyclodeaminase | IIF (when anti-LKM1 antibodies are negative) | Few studies with patients carrying these antibodies without anti-LKM1 More severe and less responsive to treatment forms of AIH |
| 30–40% of patients with AIH-2; only 10% of AIH-2 patients with these antibodies alone | Homogenous reactivity in hepatocytes, with fading fluorescence reactivity around centrilobular venules; no reactivity in proximal tubules | ||
| More frequently in association with anti-LKM1 | Immunoblotting: 62 kDa with liver antigen sources | ||
| Other techniques: immunodiffusion, ELISA | |||
| Anti-soluble liver/liver pancreas antibodies (anti-SLA/LP) One-third of patients with AIH without the classical markers | Sep (O-phosphoserine) tRNA: Sec (selenocysteine) tRNA synthase; (SepSecS → anti-SepSecS) | ELISA, immunoblotting, line immunoassay No reactivity by IIF | More relapses after treatment withdrawal 90% reactivity together with anti-RO 52 antibodies) High association with HLA DR3 Higher levels of γglobulins |
| More frequently detected in AIH-1 than AIH-2 | |||
| 15–20% of all AIH patients |
AIH, type 1 autoimmune hepatitis; AIH-2, type 2 autoimmune hepatitis; ASMA, anti-smooth muscle antibodies; ANA, antinuclear antibodies; anti-LKM1, anti-liver kidney microsome antibodies type 1; Anti-SLA/LP: anti-soluble liver/liver pancreas antibodies; IFI: indirect immunofluorescence.