Secretion of anti-citrulline-containing peptide antibody by B lymphocytes in rheumatoid arthritis

Objective. To understand the regulation of anticitrulline-containing peptid e antibody (anti-CCP) production in rheumatoid arthritis (RA), production o f 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 interl eukin-10 or anti-CD3-activated T cells. Total IgM and IgM-anti-CCP were det ected 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 health y controls and RA patients following coculture with activated T cells or ap plication of the CD40 activation system, whereas no production could be det ected 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-seronegat ive patients, actively produced IgM-anti-CCP without stimulation. The frequ ency of spontaneous production of IgM-anti-CCP among the IgM-secreting cell s ranged from 2.2% to 25%, Conclusion. These results indicate the presence of B cell precursors for an ti-CCP autoantibodies that are able to produce antibodies upon stimulation in the PB B cell repertoire of healthy controls and patients with RA, In co ntrast, B cells that actively secreted anti-CCP were specifically present i n the BM and SF compartment of anti-CCP-seropositive RA patients. The local presence of anti-CCP-secreting cells in the inflamed joints provides evide nce for an antigen-driven maturation of CCP specific B cells at the site of inflammation ih RA.