title: Mechanisms of CD23 hyperexpression on B cells from patients with rheumatoid arthritis.
abstract: OBJECTIVE
  To analyze the mechanisms involved in the characteristic hyperexpression of CD23 on peripheral blood B cells from patients with rheumatoid arthritis (RA).
  
  
  METHODS
  Peripheral blood mononuclear cells (PBMC) were obtained from patients with active disease and activated during 18 h with an anti-CD3 monoclonal antibody in the presence or absence of blocking antibodies to CD154 or CD40. PBMC were further purified by rosetting and CD23 expression was assessed on B cells by flow cytometry after double staining (CD19/CD23). Lymphocytes were also isolated from synovial fluid (SF). CD154 expression was analyzed on PB or SF CD4+ T cells after double staining (CD4/CD154) by flow cytometry at basal conditions and after different stimuli [anti-CD3 or phorbol myristic acetate (PMA) plus ionomycin]. Co-culture experiments between SF and PB cells were performed to analyze the involvement of the CD40-CD154 interaction on CD23 expression. CD154 and CD23 expression was also analyzed on synovial membrane by immunohistochemical techniques.
  
  
  RESULTS
  A high proportion of activated CD23 B cells was detected in patients with RA. Blocking experiments with both anti-CD40 and anti-CD154 Mab showed a significant reduction in the proportion of PB B cells expressing CD23. Following activation with anti-CD3 Mab or PMA plus ionomycin, CD154 expression was mainly induced on PB CD4+ T cells. In co-culture experiments, SF T cells were more efficient than PB T cells in inducing CD40 dependent CD23 expression on PB B cells. In addition, CD4+ T cells from synovial membrane clearly expressed CD154.
  
  
  CONCLUSIONS
  Our results establish a link between CD154-CD40 pathway and CD23 expression on PB B cells from patients with RA. T cells from the synovial microenvironment were active participants in this CD23 expression, presumably in the context of cell recirculation.
authors.affiliation: Services of Rheumatology and Pathology, Hospital Clínico San Carlos, Madrid, Spain.
authors.forename: S
authors.initials: S
authors.lastname: De Miguel
authors.forename: B
authors.initials: B
authors.lastname: Galocha
authors.forename: J A
authors.initials: JA
authors.lastname: Jover
authors.forename: A
authors.initials: A
authors.lastname: Bañares
authors.forename: C
authors.initials: C
authors.lastname: Hernández-García
authors.forename: J A
authors.initials: JA
authors.lastname: García-Asenjo
authors.forename: B
authors.initials: B
authors.lastname: Fernández-Gutiérrez
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D019013:CD40 Antigens / Q000276:immunology; D023201:CD40 Ligand / Q000096:biosynthesis / Q000276:immunology; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D017455:Receptors, IgE / Q000096:biosynthesis*; D013583:Synovial Membrane / Q000166:cytology / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D019013:CD40 Antigens; D017455:Receptors, IgE; D023201:CD40 Ligand