title: CD27-IgD- memory B cells are modulated by in vivo interleukin-6 receptor (IL-6R) blockade in rheumatoid arthritis.
abstract: BACKGROUND
  Enhanced B cell activity, particularly memory B cells have gained interest in evaluating response during therapies with biologics. CD27-IgD- double-negative (DN) B cells lacking the conventional memory marker CD27 are reported to be part of the memory compartment, however, only scarce data is available for rheumatoid arthritis (RA). We therefore focused on DN B cells in RA, studied their isotypes and modulation during interleukin-6 receptor (IL-6R) inhibition by tocilizumab (TCZ).
  
  
  METHODS
  DN B cells were phenotypically analyzed from 40 RA patients during TCZ at baseline week 12, week 24 and 1 year. A single B cell polymerase chain reaction (PCR) approach was used to study Ig receptors, VH gene rearrangements and specific isotypes.
  
  
  RESULTS
  Phenotypic analysis showed a significantly expanded population of DN B cells in RA which contain a heterogeneous mixture of IgG-, IgA- and IgM-expressing cells with a clear dominance of IgG+ cells. DN B cells carry rearranged heavy chain gene sequences with a diversified mutational pattern consistent with memory B cells. In contrast to tumor necrosis factor alpha (TNF-α) inhibition, a significant reduction in mutational frequency of BCR gene rearrangements at week 12, 24 and 1 year (P <0.0001) was observed by in vivo IL-6R inhibition. These changes were observed for all BCR isotypes IgG, IgA and IgM at week 12, 24 and 1 year (P <0.0001). IgA-RF, IgA serum level and IgA+ DN B cells decreased significantly (P <0.05) at week 12 and week 24 during TCZ. Patients with a good European League Against Rheumatism (EULAR) response to TCZ had less DN B cells at baseline as compared to moderate responders (P = 0.006). Univariate logistic regression analysis revealed that the frequency of DN B cells at baseline is inversely correlated to a subsequent good EULAR response (P = 0.024) with an odds ratio of 1.48 (95% confidence interval as 1.05 to 2.06).
  
  
  CONCLUSIONS
  In RA, the heterogeneous DN B cell compartment is expanded and dominated by IgG isotype. TCZ can modulate the mutational status of DN Ig isotype receptors over 1 year. Interestingly, the frequency of DN B cells in RA may serve as a baseline predictor of subsequent EULAR response to TCZ.
authors.affiliation: Department of Medicine II, Rheumatology and Clinical Immunology, University of Würzburg, Oberdürrbacher Str. 6, D-97080, Würzburg, Germany. Mahmood_Z@ukw.de.
authors.forename: Zafar
authors.initials: Z
authors.lastname: Mahmood
authors.affiliation: Department of Medicine II, Rheumatology and Clinical Immunology, University of Würzburg, Oberdürrbacher Str. 6, D-97080, Würzburg, Germany. Khalid.Muhammad@uni-wuerzburg.de.|Department of Molecular Pathology, Institute of Pathology University of Würzburg, Josef-Schneider-Str. 2, D-97080, Würzburg, Germany. Khalid.Muhammad@uni-wuerzburg.de.
authors.forename: Khalid
authors.initials: K
authors.lastname: Muhammad
authors.affiliation: Department of Medicine II, Rheumatology and Clinical Immunology, University of Würzburg, Oberdürrbacher Str. 6, D-97080, Würzburg, Germany. Schmalzing_M@ukw.de.
authors.forename: Marc
authors.initials: M
authors.lastname: Schmalzing
authors.affiliation: Department of Medicine II, Rheumatology and Clinical Immunology, University of Würzburg, Oberdürrbacher Str. 6, D-97080, Würzburg, Germany. Dr.PetraRoll@gmx.com.
authors.forename: Petra
authors.initials: P
authors.lastname: Roll
authors.affiliation: CC12, Department of Medicine /Rheumatology and Clinical Immunology, Charite Universitätsmedizin Berlin and DRFZ Berlin, Charitéplatz 1, D-10117, Berlin, Germany. thomas.doerner@charite.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dörner
authors.affiliation: Department of Medicine II, Rheumatology and Clinical Immunology, University of Würzburg, Oberdürrbacher Str. 6, D-97080, Würzburg, Germany. Tony_H@ukw.de.
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Tony
mesh_terms: D000328:Adult; D000368:Aged; D061067:Antibodies, Monoclonal, Humanized / Q000494:pharmacology / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000188:drug therapy; D001402:B-Lymphocytes / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D007072:Immunoglobulin D / Q000097:blood*; D008297:Male; D008875:Middle Aged; D019947:Receptors, Interleukin-6 / Q000037:antagonists & inhibitors*; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000097:blood*
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D007072:Immunoglobulin D; D019947:Receptors, Interleukin-6; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; C502936:tocilizumab