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The peculiar autoimmunity of primary biliary cirrhosis
Author(s) -
Mackay Ian R.,
Whittingham Senga,
Fida Shahnaz,
Myers Mark,
Ikuno Nobuhiro,
Gershwin M. Eric
Publication year - 2000
Publication title -
immunological reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.839
H-Index - 223
eISSN - 1600-065X
pISSN - 0105-2896
DOI - 10.1034/j.1600-0528.2002.017410.x
Subject(s) - primary biliary cirrhosis , epitope , autoantibody , biology , autoimmunity , molecular mimicry , pyruvate dehydrogenase complex , anti nuclear antibody , protein subunit , epitope mapping , antibody , antigen , autoimmune disease , microbiology and biotechnology , immunology , genetics , biochemistry , gene , enzyme
Summary: Autoantibodies to mitochondria (AMA, anti‐M2) are a serologic hallmark of primary biliary cirrhosis (PBC). These react with three structurally and functionally related multienzymic complexes, the 2‐oxoacid dehydrogenase complexes, but chiefly with the E2 subunit of pyruvate dehydrogenase complex (PDC‐E2). Their very close (95%) and specific association with PBC underpins the autoimmune concept of pathogenesis of that disease, notwithstanding several non‐congruent features. Detailed studies, including structural analysis of epitopes, do not disclose how these autoantibodies originate. Their ubiquity in PBC has overshadowed the existence of a second set of relatively PBC‐specific autoantibodies to nuclear antigens for which reactants have been cloned and characterized. These include centromeric proteins; proteins of the nuclear pore complex; nuclear dot proteins, which include Sp‐100 and the promyelocytic leukemia antigen; and a recently identified autoantigen, SOX13. Certain of these reactants are DNA‐binding proteins with transcriptional regulatory activity. Thus serum from individuals with the same clinical syndrome can have autoimmune reactivity to disparate mitochondrial and nuclear constituents in different cellular compartments. Antibody probing of phage displayed random peptide libraries, together with epitope scanning using overlapping sequential octameric peptides from the PDC‐E2 sequence, showed that the discontinuous motifs MH, FV(E) and SYP contributed to a predicted conformational antibody epitope in the inner lipoyl domain of PDC‐E2.