title: Mimicry peptides of human PDC-E2 163-176 peptide, the immunodominant T-cell epitope of primary biliary cirrhosis.
abstract: The human PDC-E2 163-176 peptide (GDLLAEIETDKATI) is an immunodominant autoreactive T-cell epitope in patients with primary biliary cirrhosis (PBC), restricted by HLA DRB4*0101. We have previously reported that the ExDK sequence is essential for recognition of this epitope and identified 1 mimicry peptide, Escherichia coli PDC-E2 peptide (EQSLITVEGDKASM), which can activate human PDC-E2 163-176 peptide-reactive T-cell clones. In the present study, to further investigate mimicry peptides possibly involved in PBC, we generated 13 different T-cell clones reactive to the human PDC-E2 163-176 peptide following repeated in vitro stimulation of peripheral T lymphocytes with the human PDC-E2 163-176 peptide (native peptide) and tested for the reactivity of these T-cell clones to 30 different mimicry peptides derived from various self- and nonself proteins that have an ExDK-sequence. We found 7 mimicry peptides derived from microbial proteins that can activate at least 1 of these T-cell clones; 7 of 7 T-cell clones from patients with PBC and 2 of 6 T-cell clones from healthy subjects were activated by at least 1 to 6 different mimicry peptides. Two of 6 T-cell clones from healthy subjects were activated by specific mimicry peptides more strongly than by the native peptide, and 2 of 6 T-cell clones from healthy subjects were not activated by any mimicry peptides tested. Thus, the pattern and degree of activation by mimicry peptides differed in each T-cell clone, indicating the presence of a diverse spectrum of autoreactive T cells that are reactive to a single minimal epitope of the human PDC-E2 163-176 peptide.
authors.affiliation: The First Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Shimoda
authors.forename: M
authors.initials: M
authors.lastname: Nakamura
authors.forename: H
authors.initials: H
authors.lastname: Shigematsu
authors.forename: H
authors.initials: H
authors.lastname: Tanimoto
authors.forename: T
authors.initials: T
authors.lastname: Gushima
authors.forename: M E
authors.initials: ME
authors.lastname: Gershwin
authors.forename: H
authors.initials: H
authors.lastname: Ishibashi
mesh_terms: D002455:Cell Division / Q000187:drug effects; D002999:Clone Cells / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis; D051047:Dihydrolipoyllysine-Residue Acetyltransferase; D006801:Humans; D016056:Immunodominant Epitopes; D008105:Liver Cirrhosis, Biliary / Q000276:immunology*; D018716:Molecular Mimicry; D010446:Peptide Fragments / Q000276:immunology* / Q000494:pharmacology; D011768:Pyruvate Dehydrogenase Complex / Q000276:immunology* / Q000494:pharmacology; D013601:T-Lymphocytes / Q000145:classification / Q000166:cytology / Q000276:immunology* / Q000378:metabolism
chemical_list: D016207:Cytokines; D016056:Immunodominant Epitopes; D010446:Peptide Fragments; D011768:Pyruvate Dehydrogenase Complex; D051047:Dihydrolipoyllysine-Residue Acetyltransferase