title: Recognition of new citrulline-containing peptide epitopes by autoantibodies produced in vivo and in vitro by B cells of rheumatoid arthritis patients.
abstract: Anti-citrullinated peptide/protein antibodies (ACPAs) are highly sensitive and specific markers of rheumatoid arthritis (RA). Identification of peptide epitopes that may detect different subgroups of RA patients might have diagnostic and prognostic significance. We have investigated citrulline- and arginine-containing peptide pairs derived from filaggrin, collagen or vimentin, and compared this citrulline-peptide panel with the serological assays conventionally used to detect ACPAs. Furthermore, we studied if the same citrulline-peptides identify antibody-secreting cells in in vitro cultures of RA B cells. Recognition of citrulline- and arginine-containing filaggrin, vimentin and collagen peptide epitopes were tested by Multipin ELISA system, by indirect ELISA and by a peptide-specific microarray. B cells were purified from blood by negative selection; antibody-producing cells were enumerated by ELISPOT assay. The panel composed of citrulline-peptide epitopes of filaggrin, collagen and vimentin was recognized by RA sera with a sensitivity and specificity comparable with the currently used tests. Moreover, the combined citrulline-peptide panel including the new short epitope peptide of filaggrin, fil311-315, also identified nearly one-third of RA cases that were negative for antibodies against cyclic citrullinated peptides, mutated citrullinated vimentin or for rheumatoid factor. The results with the peptide-specific microarray have shown that although most ACPAs recognizing the four citrulline peptides are IgG, some of them specifically recognizing citrulline-containing filaggrin peptides (fil311-315 and fil306-326) are IgM, and so may be produced either by newly formed activated B cells or by unswitched B memory cells. Furthermore, the citrulline-peptides of filaggrin and vimentin detect ACPA-producing cells, and so could also be applied to study the B cells of RA patients.
authors.affiliation: Department of Immunology, Eötvös Loránd University, Budapest, Hungary.
authors.forename: Eszter
authors.initials: E
authors.lastname: Szarka
authors.forename: Fruzsina
authors.initials: F
authors.lastname: Babos
authors.forename: Anna
authors.initials: A
authors.lastname: Magyar
authors.forename: Krisztina
authors.initials: K
authors.lastname: Huber
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Szittner
authors.forename: Krisztián
authors.initials: K
authors.lastname: Papp
authors.forename: József
authors.initials: J
authors.lastname: Prechl
authors.forename: Judit
authors.initials: J
authors.lastname: Pozsgay
authors.forename: Zsuzsa
authors.initials: Z
authors.lastname: Neer
authors.forename: Monika
authors.initials: M
authors.lastname: Ádori
authors.forename: György
authors.initials: G
authors.lastname: Nagy
authors.forename: Bernadette
authors.initials: B
authors.lastname: Rojkovich
authors.forename: Tamás
authors.initials: T
authors.lastname: Gáti
authors.forename: Judit
authors.initials: J
authors.lastname: Kelemen
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Baka
authors.forename: Márta
authors.initials: M
authors.lastname: Brózik
authors.forename: Borbála
authors.initials: B
authors.lastname: Pazár
authors.forename: Gyula
authors.initials: G
authors.lastname: Poór
authors.forename: Ferenc
authors.initials: F
authors.lastname: Hudecz
authors.forename: Gabriella
authors.initials: G
authors.lastname: Sármay
mesh_terms: D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D002956:Citrulline / Q000276:immunology*; D003094:Collagen / Q000276:immunology; D003429:Cross Reactions; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes; D005260:Female; D000091344:Filaggrin Proteins; D006801:Humans; D007381:Intermediate Filament Proteins / Q000276:immunology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D014746:Vimentin / Q000276:immunology
chemical_list: D001323:Autoantibodies; D000939:Epitopes; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D014746:Vimentin; D002956:Citrulline; D003094:Collagen
keywords: B cell; anti-citrullinated peptide antibodies; citrulline-peptide; diagnosis; rheumatoid arthritis