title: Serum BAFF and APRIL levels in patients with IgG4-related disease and their clinical significance.
abstract: BACKGROUND
  B cell-activating factor of the tumor necrosis factor family (BAFF) and a proliferation-inducing ligand (APRIL) play a crucial role in B cell development, survival, and antibody production. Here we analyzed the serum levels of BAFF and APRIL and their respective clinical associations in patients with an immunoglobulin (Ig) G4-related disease (IgG4-RD).
  
  
  METHODS
  We measured serum levels of BAFF and APRIL in patients with IgG4-RD, primary Sjögren's syndrome (pSS), and healthy individuals. Serum BAFF and APRIL levels in IgG4-RD were assessed for correlations with serological parameters, including Ig, particularly IgG4, and the number of affected organs. Serum BAFF and APRIL levels in IgG4-RD were monitored during glucocorticoid (GC) therapy.
  
  
  RESULTS
  Serum BAFF and APRIL levels in patients with IgG4-RD were significantly higher (P < 0.01) than in healthy individuals. The BAFF levels of patients with IgG4-RD were comparable to those of patients with pSS. Although clinical parameters, such as serum IgG4 and the number of affected organs, were not correlated with the levels of BAFF, serum APRIL levels were inversely correlated with serum IgG4 levels (r = -0.626, P < 0.05). While serum BAFF levels decreased following GC therapy, serum APRIL levels increased during follow-up.
  
  
  CONCLUSIONS
  These results indicate that BAFF and APRIL might be useful markers for predicting disease activity in IgG4-RD. Further studies are needed to elucidate the role of BAFF and APRIL in the pathogenesis of IgG4-RD.
authors.affiliation: Department of Rheumatology and Clinical Immunology, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Kyoto 606-8507, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kiyama
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kawabata
authors.forename: Yuji
authors.initials: Y
authors.lastname: Hosono
authors.forename: Koji
authors.initials: K
authors.lastname: Kitagori
authors.forename: Naoichiro
authors.initials: N
authors.lastname: Yukawa
authors.forename: Hajime
authors.initials: H
authors.lastname: Yoshifuji
authors.forename: Koichiro
authors.initials: K
authors.lastname: Omura
authors.forename: Takao
authors.initials: T
authors.lastname: Fujii
authors.forename: Tsuneyo
authors.initials: T
authors.lastname: Mimori
mesh_terms: D000328:Adult; D000368:Aged; D053264:B-Cell Activating Factor / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012859:Sjogren's Syndrome / Q000097:blood* / Q000175:diagnosis*; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13 / Q000097:blood*
chemical_list: D053264:B-Cell Activating Factor; D015415:Biomarkers; D007074:Immunoglobulin G; C505719:TNFSF13B protein, human; D053300:Tumor Necrosis Factor Ligand Superfamily Member 13