Autoantibodies and Autoantigens in Autoimmune Hepatitis

Christian P. Strassburg, MD, Michael P. Manns, MD


Semin Liver Dis. 2002;22(4) 

In This Article

Hepatitis D-Associated Microsomal Autoantibodies

LKM-3 autoantibodies are directed against UGT proteins with a molecular weight of 55 kD. They occur in 6 to 14% of patients with hepatitis D in addition to 10% of patients with AIH type 2. In contrast to LKM-1 and LKM-2 autoantibodies, which on immunofluorescence stain liver and kidney tissue only, with LKM-3 autoantibodies additional fluorescence signals may be present with tissue from the pancreas, adrenal gland, thyroid, and stomach. Western blot assay revealed several molecular targets around 55 kD.[80,81] The molecular targets of the LKM-3 autoantibody were identified as UGTs of family 1.[80,81] LKM-3 autoantibodies are not detected in sera from patients with chronic hepatitis B, chronic hepatitis C, primary biliary cirrhosis, primary sclerosing cholangitis, or lupus erythematosus.[80] Autoantibody titers in patients with chronic HDV infection are usually lower than they are in patients with AIH type 2.[81] Recently, genetic polymorphisms were detected in the genes encoding UGTIA proteins on chromosome 2.[105,106,107] These polymorphisms, which appear to play a role in cancer development, encode UGT proteins with altered catalytic activity.[106] Whether polymorphisms of the UGTIA gene locus contribute to the development of B cell autoimmunity remains to be elucidated.


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