Sera of patients with chronic hepatitis delta
virus infection stained the nuclear periphery in indirect immunofluorescence. Using proteins of isolated nuclei, isolated nuclear matrices, the nuclear pore complexlamina fraction and purified lamins A and C as antigen source in immunoblotting experiments, nuclear lamin C was identified as the reactive antigen. Most sera tested (8 of 10) recognized nuclear lamin C exclusively, but not the nuclear lamins A and B. Antibodies reacting with both nuclear lamins A and C, which share extensive sequence homologies, have been reported to occur in autoimmune hepatitis and primary biliary cirrhosis. The present 5dings suggest that the novel autoantibody associated with chronic hepatitis delta virus infection recognizes an epitope localized in the short carboxyterminal region of nuclear lamin C. (HEPATOLUGY 1990;12:1129-1133.)
Antibodies t o nuclear antigens are a constant feature of untreated chronic autoimmune or lupoid hepatitis and represent a serological marker in the diagnosis of this disease. During the last decade numerous studies have shown that these sera contain a heterogenous population of nuclear antibodies recognizing nucleic acids, RNA-protein complexes, and centromeric and other proteins (1-4).
Recently a novel antinuclear antibody has been reported to occur in sera of patients with hepatitis delta virus (HDV)-induced chronic hepatitis, which stained the nuclear region in immunofluorescence (5). However, the reacting antigen was not characterized.
In this study we identify nuclear lamin C, a protein of the nuclear envelope, as the major antigen recognized by the antinuclear antibodies in HDV-induced chronic liver disease. Antibodies to nuclear lamins have previously been observed in chronic autoimmune hepatitis and PBC (6, 7). These antibodies, however, recognized both the related nuclear lamins, A and C. The selective recognition of lamin C by sera from patients with HDV-induced chronic liver disease is surprising, consid-