From the Guidelines
The most specific antibody for Autoimmune Hepatitis (AIH) is anti-LKM-1.
Autoantibodies in AIH
- Type 1 AIH is associated with the presence of either ANA or ASMA in the serum and accounts for about 75% of patients 1.
- Type 2 AIH is associated with the presence of either anti-liver kidney microsomal-1 (LKM-1) or anti-liver cytosolic-1 (LC-1) antibodies 1.
- Anti-LKM-1 antibodies target several epitopes of hepatic cytochromes, specifically cytochrome P-450 2D6, and have a high specificity for AIH 1.
- Serum antibodies to double-stranded DNA are found in 15% of patients with AIH and are highly specific for either AIH or systemic lupus erythematosus 1.
Diagnostic Algorithm
- The diagnosis of AIH is based on histological abnormalities, characteristic clinical and laboratory findings, and the presence of one or more characteristic autoantibodies 1.
- ANA, SMA, and LKM1 should be assessed in all pediatric patients at presentation, and in adults if suspected AIH 1.
- The absence of ANA, SMA, and LKM1 justifies additional serological tests, including anti-SLA, atypical pANCA, tissue transglutaminase, and AMA 1.
From the Research
Autoantibodies in Autoimmune Hepatitis
The detection of specific autoantibodies is crucial for the diagnosis and differentiation of autoimmune hepatitis (AIH) types. The most specific antibodies for AIH are:
- Anti-liver kidney microsomal antibody type 1 (anti-LKM1) for type 2 AIH 2, 3
- Anti-soluble liver antigen (anti-SLA) antibody, which cannot be detected by indirect immunofluorescence (IIF) and requires a molecular-based assay 4
- Anti-liver cytosol type 1 (anti-LC1) antibody, often found in association with anti-LKM1 2, 3
Characteristics of Autoantibodies
Key characteristics of autoantibodies in AIH include:
- Anti-nuclear antibody (ANA) with a homogeneous IIF pattern on HEp2 cells, often found in type 1 AIH 4
- Anti-smooth muscle antibody (SMA), frequently associated with ANA in type 1 AIH 5, 6, 2, 3
- Atypical perinuclear anti-neutrophil antibody (pANCA), which can be detected in AIH type 1 and primary sclerosing cholangitis 5, 4
Target Autoantigens
The target autoantigens for these antibodies have been identified as: