title: Secretion of anti-citrulline-containing peptide antibody by B lymphocytes in rheumatoid arthritis.
abstract: OBJECTIVE
  To understand the regulation of anti-citrulline-containing peptide antibody (anti-CCP) production in rheumatoid arthritis (RA), production of anti-CCP by B cells derived from peripheral blood (PB), bone marrow (BM), and synovial fluid (SF) was examined.
  
  
  METHODS
  Purified PB and SF B cells were isolated by negative selection and then cultured in the absence or presence of L-CD40 ligand cells and interleukin-10 or anti-CD3-activated T cells. Total IgM and IgM-anti-CCP were detected after 14 days of culture by enzyme-linked immunosorbent assay. Enzyme-linked immunospot assays were performed to analyze the frequency of cells that spontaneously produced IgM-anti-CCP in BM and SF B cells.
  
  
  RESULTS
  IgM-anti-CCP autoantibodies were induced in PB B cells from healthy controls and RA patients following coculture with activated T cells or application of the CD40 activation system, whereas no production could be detected when PB B cells were cultured in the absence of a stimulus. SF and BM B cells from anti-CCP-seropositive RA patients, but not anti-CCP-seronegative patients, actively produced IgM-anti-CCP without stimulation. The frequency of spontaneous production of IgM-anti-CCP among the IgM-secreting cells ranged from 2.2% to 25%.
  
  
  CONCLUSIONS
  These results indicate the presence of B cell precursors for anti-CCP autoantibodies that are able to produce antibodies upon stimulation in the PB B cell repertoire of healthy controls and patients with RA. In contrast, B cells that actively secreted anti-CCP were specifically present in the BM and SF compartment of anti-CCP-seropositive RA patients. The local presence of anti-CCP-secreting cells in the inflamed joints provides evidence for an antigen-driven maturation of CCP-specific B cells at the site of inflammation in RA.
authors.affiliation: Leiden University Medical Center, The Netherlands.
authors.forename: C C
authors.initials: CC
authors.lastname: Reparon-Schuijt
authors.forename: W J
authors.initials: WJ
authors.lastname: van Esch
authors.forename: C
authors.initials: C
authors.lastname: van Kooten
authors.forename: G A
authors.initials: GA
authors.lastname: Schellekens
authors.forename: B A
authors.initials: BA
authors.lastname: de Jong
authors.forename: W J
authors.initials: WJ
authors.lastname: van Venrooij
authors.forename: F C
authors.initials: FC
authors.lastname: Breedveld
authors.forename: C L
authors.initials: CL
authors.lastname: Verweij
mesh_terms: D000917:Antibody Formation; D001172:Arthritis, Rheumatoid / Q000097:blood*; D001323:Autoantibodies / Q000378:metabolism; D001402:B-Lymphocytes / Q000378:metabolism*; D002956:Citrulline / Q000276:immunology*; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D013582:Synovial Fluid / Q000166:cytology
chemical_list: D001323:Autoantibodies; D007075:Immunoglobulin M; D002956:Citrulline