title: Epidermal polymeric immunoglobulin receptors: leads from intraepidermal neutrophilic IgA dermatosis-type IgA pemphigus.
abstract: In this study, we attempted to identify unknown autoantigen for intraepidermal neutrophilic IgA dermatosis-type IgA pemphigus by novel IgA-specific immunoprecipitation. Mass-spectrometry study identified polymeric immunoglobulin receptor (PIGR) as the candidate protein, and we confirmed that PIGR expressed in both epidermis and cultured keratinocytes. Eukaryotic recombinant protein of PIGR expressed in COS7 cells was reacted with both patient and normal sera, indicating that PIGR binds physiologically to IgA. To detect antigen-specific binding by IgA autoantibodies, we performed several experiments using deglycosylated PIGR and F(ab)2 fragments from patient sera. However, these analyses suggested that patient IgA bound physiologically, but not immunologically, to PIGR. Nevertheless, our study provided two important insights. Newly developed IgA-immunoprecipitation system should be a useful tool in the future study of identification of antigens for IgA autoantibodies. Detection of epidermal PIGR in this study confirmed previous results and indicated possible immunological role of PIGR in epidermis.
authors.affiliation: Department of Dermatology, Kurume University School of Medicine, and Kurume University Institute of Cutaneous Cell Biology, Fukuoka, Japan.
authors.forename: Atsunari
authors.initials: A
authors.lastname: Tsuchisaka
authors.forename: Norito
authors.initials: N
authors.lastname: Ishii
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hamada
authors.forename: Kwesi
authors.initials: K
authors.lastname: Teye
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Sogame
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Koga
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tsuruta
authors.forename: Chika
authors.initials: C
authors.lastname: Ohata
authors.forename: Minao
authors.initials: M
authors.lastname: Furumura
authors.forename: Takashi
authors.initials: T
authors.lastname: Hashimoto
mesh_terms: D001324:Autoantigens; D002478:Cells, Cultured; D004817:Epidermis / Q000276:immunology; D005136:Eye Proteins; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D047468:Immunoprecipitation / Q000379:methods*; D015603:Keratinocytes; D009504:Neutrophils / Q000276:immunology; D010392:Pemphigus / Q000276:immunology* / Q000473:pathology; D010446:Peptide Fragments; D019056:Receptors, Polymeric Immunoglobulin / Q000097:blood*
chemical_list: D001324:Autoantigens; D005136:Eye Proteins; D007070:Immunoglobulin A; D010446:Peptide Fragments; D019056:Receptors, Polymeric Immunoglobulin; C052615:peptide M, retinal S antigen
keywords: IEN-type IgA pemphigus; IgA autoantibody; immunoprecipitation; keratinocyte; polymeric immunoglobulin receptor