title: Mapping of melanin-concentrating hormone receptor 1 B cell epitopes predicts two major binding sites for vitiligo patient autoantibodies.
abstract: The melanin-concentrating hormone receptor 1 (MCHR1) has been identified as a B cell autoantigen in vitiligo with antibodies to the receptor detectable in binding and function-blocking assays. Two epitope domains (amino acids 1-138 and 139-298) have been previously identified. In this study, we aimed to further define the epitope specificity of MCHR1 antibodies using phage-display technology and to identify the epitopes recognised by receptor antibodies detected in MCHR1 function-blocking assays. Antibody reactivity to MCHR1 peptides 51-80, 85-98, 154-158 and 254-260 was identified by phage-display and subsequently confirmed in phage ELISA in 2/12, 5/12, 3/12 and 6/12 of vitiligo patients, respectively. The results suggest that major autoantibody epitopes are localised in the 85-98 and 254-260 amino acid regions of MCHR1 with minor epitopes in amino acid sequences 51-80 and 154-158. Antibodies with MCHR1 function-blocking activity were determined to recognise epitope 254-260, this being the first epitope to be reported as a target site for antibodies that block the function of the receptor.
authors.affiliation: School of Medicine and Biomedical Sciences, University of Sheffield, Sheffield, UK.
authors.forename: Nikos G
authors.initials: NG
authors.lastname: Gavalas
authors.forename: Raju V S R K
authors.initials: RV
authors.lastname: Gottumukkala
authors.forename: David J
authors.initials: DJ
authors.lastname: Gawkrodger
authors.forename: Philip F
authors.initials: PF
authors.lastname: Watson
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Weetman
authors.forename: E Helen
authors.initials: EH
authors.lastname: Kemp