title: A comparative study of antibody expressions in primary biliary cirrhosis and autoimmune cholangitis using phage display.
abstract: Primary biliary cirrhosis (PBC) and autoimmune cholangitis (AIC) are serologic expressions of an autoimmune liver disease affecting biliary ductular cells. Previously we screened a phage-displayed random peptide library with polyclonal IgG from 2 Australian patients with PBC and derived peptides that identified a single conformational (discontinuous) epitope in the inner lipoyl domain of the E2 subunit of the pyruvate dehydrogenase complex (PDC-E2), the characteristic autoantigen in PBC. Here we have used phage display to investigate the reactivity of PBC sera from 2 ethnically and geographically distinct populations, Japanese and Australian, and the 2 serologic expressions, PBC and AIC. Random 7-mer and 12-mer peptide libraries were biopanned with IgG from 3 Japanese patients with PBC and 3 with AIC who did not have anti-PDC-E2. The phage clones (phagotopes) obtained were tested by capture enzyme-linked immunosorbent assay (ELISA) for reactivity with affinity-purified anti-PDC-E2, and compared with those obtained from Australian patients with PBC. Peptide sequences of the derived phagotopes and sequences derived by biopanning with irrelevant antisera were aligned to develop a guide tree based on physicochemical similarity. Both Australian and Japanese PBC-derived phagotopes were distributed in branches of the guide tree that contained the peptide sequences MH and FV previously identified as part of an immunodominant conformational epitope of PDC-E2, indicating that epitope selection was not influenced by the racial origin of the PBC sera. Biopanning with either PBC or AIC-derived IgG yielded phagotopes that reacted with anti-PDC-E2 by capture ELISA, further establishing that there is a similar autoimmune targeting in PBC and AIC.
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia.
authors.forename: N
authors.initials: N
authors.lastname: Ikuno
authors.forename: M
authors.initials: M
authors.lastname: Scealy
authors.forename: J M
authors.initials: JM
authors.lastname: Davies
authors.forename: S F
authors.initials: SF
authors.lastname: Whittingham
authors.forename: K
authors.initials: K
authors.lastname: Omagari
authors.forename: I R
authors.initials: IR
authors.lastname: Mackay
authors.forename: M J
authors.initials: MJ
authors.lastname: Rowley
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D000906:Antibodies / Q000032:analysis*; D034961:Antigens, Nuclear; D001324:Autoantigens / Q000276:immunology; D001327:Autoimmune Diseases / Q000276:immunology*; D002460:Cell Line; D002761:Cholangitis / Q000276:immunology*; D051047:Dihydrolipoyllysine-Residue Acetyltransferase; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D008105:Liver Cirrhosis, Biliary / Q000276:immunology*; D008875:Middle Aged; D009687:Nuclear Proteins / Q000276:immunology; D019151:Peptide Library; D011768:Pyruvate Dehydrogenase Complex / Q000276:immunology
chemical_list: D000906:Antibodies; D034961:Antigens, Nuclear; D001324:Autoantigens; D009687:Nuclear Proteins; D019151:Peptide Library; D011768:Pyruvate Dehydrogenase Complex; C066642:SP100 protein, human; D051047:Dihydrolipoyllysine-Residue Acetyltransferase