title: Is an epitope on keratin 17 a major target for autoreactive T lymphocytes in psoriasis?
abstract: Psoriasis is a T cell-mediated inflammatory skin disease that has been associated with infections by group A beta-haemolytic streptococci. In a previous study of patients with active psoriasis we demonstrated an increased frequency of circulating Th1-like cells that responded to 20 amino acid (aa) streptococcal M-peptides sharing sequences with human keratin. These cells disappeared after ultraviolet B (UVB)-induced clinical remission. Using T cells from the blood of 17 psoriatic patients and 17 healthy controls we have now compared the numbers of interferon-gamma (IFN-gamma)-producing cells induced by seven 18-20 aa keratin peptides and five corresponding M-peptides. The most frequent and strongest responses were observed to a peptide from keratin 17 that shares ALEEAN sequence with M-protein. The responses to this peptide were stronger than to the corresponding M-peptide containing the ALEEAN sequence. After UVB treatment T cell responses to all the M- and keratin peptides were abolished, while responses to the positive control antigen streptokinase/streptodornase (SK/SD) were not affected. These findings are consistent with the notion that aa sequences which keratin has in common with M-protein may be a major target for autoreactive T cells in psoriasis.
authors.affiliation: Department of Immunology, The National University Hospital, Reykjavik, Iceland.
authors.forename: A S
authors.initials: AS
authors.lastname: Gudmundsdottir
authors.forename: H
authors.initials: H
authors.lastname: Sigmundsdottir
authors.forename: B
authors.initials: B
authors.lastname: Sigurgeirsson
authors.forename: M F
authors.initials: MF
authors.lastname: Good
authors.forename: H
authors.initials: H
authors.lastname: Valdimarsson
authors.forename: I
authors.initials: I
authors.lastname: Jonsdottir
mesh_terms: D000595:Amino Acid Sequence; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000276:immunology*; D002352:Carrier Proteins / Q000276:immunology*; D002478:Cells, Cultured; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D005260:Female; D006801:Humans; D007633:Keratins / Q000276:immunology*; D008297:Male; D008969:Molecular Sequence Data; D010455:Peptides / Q000276:immunology; D011565:Psoriasis / Q000276:immunology* / Q000532:radiotherapy / Q000628:therapy; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D014466:Ultraviolet Rays
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D018984:Epitopes, T-Lymphocyte; D010455:Peptides; C014689:streptococcal M protein; D007633:Keratins