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Persistence of Disease‐Associated Anti–Citrullinated Protein Antibody–Expressing Memory B Cells in Rheumatoid Arthritis in Clinical Remission
Author(s) -
Pelzek Adam J.,
Grönwall Caroline,
Rosenthal Pamela,
Greenberg Jeffrey D.,
McGeachy Mandy,
Moreland Larry,
Rigby William F. C.,
Silverman Gregg J.
Publication year - 2017
Publication title -
arthritis and rheumatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.106
H-Index - 314
eISSN - 2326-5205
pISSN - 2326-5191
DOI - 10.1002/art.40053
Subject(s) - immunology , antibody , autoantibody , rheumatoid arthritis , peripheral blood mononuclear cell , b cell , memory b cell , medicine , rheumatoid factor , immune system , epitope , biology , in vitro , biochemistry
Objective In rheumatoid arthritis (RA), autoreactive B cells are pathogenic drivers and sources of anti–citrullinated protein antibodies (ACPAs) that are a diagnostic biomarker and predictor of worse long‐term prognosis. Yet, the immunobiologic significance of persistent ACPA production at the cellular level is poorly understood. This study was undertaken to investigate the representation of ACPA‐expressing switched‐memory B cells in RA. Methods In a cross‐sectional study of RA patients, we investigated the presence of continued defects in immune homeostasis as a function of disease activity. Using an enzyme‐linked immunosorbent assay (ELISA) and a sensitive multiplex bead‐based immunoassay, we characterized fine binding antibody specificities in sera, synovial fluid (SF), and B cell culture supernatants. In this manner, we determined the frequency and epitope reactivity patterns of ACPAs produced by SF B cells and switched‐memory blood B cells and compared the latter to serum ACPA levels and disease activity scores. Results Cultured B cells from SF were shown to spontaneously secrete ACPAs, while constitutive IgG autoantibody production by peripheral blood mononuclear cells (PBMCs) was substantially less frequent. After in vitro stimulation, PBMCs secreted IgG ACPA that was overwhelmingly from switched‐memory B cells, across all patient groups treated with methotrexate and/or a tumor necrosis factor inhibitor. Intriguingly, the frequencies of ACPA‐expressing switched‐memory B cells significantly correlated with serum IgG anti–cyclic citrullinated peptide 3 (r = 0.57, P = 0.003). Moreover, treatment‐induced clinical remission had little or no effect on the circulating burden of switched‐memory ACPA‐expressing B cells, in part explaining the continued dysregulation of humoral immunity. Conclusion Our findings rationalize why therapeutic cessation most often results in disease reactivation and clinical flare. Hence, a clinical disease activity score is not a reliable indicator of the resolution of pathologic recirculating B cell autoimmunity.