title: Persistence of Disease-Associated Anti-Citrullinated Protein Antibody-Expressing Memory B Cells in Rheumatoid Arthritis in Clinical Remission.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: New York University School of Medicine, New York, New York.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Pelzek
authors.affiliation: New York University School of Medicine, New York, New York.
authors.forename: Caroline
authors.initials: C
authors.lastname: Grönwall
authors.affiliation: New York University School of Medicine, New York, New York.
authors.forename: Pamela
authors.initials: P
authors.lastname: Rosenthal
authors.affiliation: New York University School of Medicine, New York, New York.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Greenberg
authors.affiliation: University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Mandy
authors.initials: M
authors.lastname: McGeachy
authors.affiliation: University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Larry
authors.initials: L
authors.lastname: Moreland
authors.affiliation: Dartmouth Medical School, Lebanon, New Hampshire.
authors.forename: William F C
authors.initials: WFC
authors.lastname: Rigby
authors.affiliation: New York University School of Medicine, New York, New York.
authors.forename: Gregg J
authors.initials: GJ
authors.lastname: Silverman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000918:Antibody Specificity; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000276:immunology*; D001323:Autoantibodies / Q000032:analysis* / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D005260:Female; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology*; D012074:Remission Induction; D012720:Severity of Illness Index; D000067251:Symptom Flare Up; D013582:Synovial Fluid / Q000276:immunology
chemical_list: D001323:Autoantibodies; D000939:Epitopes; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide