title: Patients with antineutrophil cytoplasmic antibody-associated vasculitis have defective Treg cell function exacerbated by the presence of a suppression-resistant effector cell population.
abstract: OBJECTIVE
  The development of pathogenic antineutrophil cytoplasmic antibodies (ANCAs) can result in systemic small vessel vasculitis. However, the breakdown in immune tolerance that results in the induction and persistence of ANCAs is not well understood. We undertook this study to test our hypothesis that abnormal T cell regulation is central to disease pathogenesis in patients with ANCA-associated vasculitis (AAV).
  
  
  METHODS
  Peripheral blood samples were obtained from 62 patients with AAV and 19 healthy controls for flow cytometric analysis of CD4+ T cell populations. Functional T cell studies were performed with fluorescence-activated cell sorted CD4+ T cell populations stimulated with anti-CD3/anti-CD28.
  
  
  RESULTS
  We demonstrated two separate abnormalities in T cell regulation in patients with AAV. First, we showed that the Treg cell frequency was increased in the peripheral blood of patients with active disease, but Treg cells from patients with AAV had decreased suppressive function. Treg cells from patients with active disease disproportionately used a FoxP3 isoform lacking exon 2, which might alter Treg cell function. Second, we identified a CD4+ T cell population with increased frequency that was resistant to Treg cell suppression, produced proinflammatory cytokines, and was antigen experienced.
  
  
  CONCLUSIONS
  AAV is associated with disruption of the suppressive Treg cell network and with increased frequency of a distinct proinflammatory effector T cell subset that comprises the majority of peripheral CD4+ T cells.
authors.affiliation: University of North Carolina, Chapel Hill, NC, USA. meghan_free@med.unc.edu
authors.forename: Meghan E
authors.initials: ME
authors.lastname: Free
authors.forename: Donna O'Dell
authors.initials: DO
authors.lastname: Bunch
authors.forename: Julie Anne
authors.initials: JA
authors.lastname: McGregor
authors.forename: Britta E
authors.initials: BE
authors.lastname: Jones
authors.forename: Elisabeth A
authors.initials: EA
authors.lastname: Berg
authors.forename: Susan L
authors.initials: SL
authors.lastname: Hogan
authors.forename: Yichun
authors.initials: Y
authors.lastname: Hu
authors.forename: Gloria A
authors.initials: GA
authors.lastname: Preston
authors.forename: J Charles
authors.initials: JC
authors.lastname: Jennette
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Falk
authors.forename: Maureen A
authors.initials: MA
authors.lastname: Su
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D016022:Case-Control Studies; D005260:Female; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000276:immunology; D006801:Humans; D007108:Immune Tolerance; D008297:Male; D008875:Middle Aged; D020033:Protein Isoforms / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D055815:Young Adult
chemical_list: C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D020033:Protein Isoforms
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