title: Analysis of IgG4-positive clones in affected organs of IgG4-related disease.
abstract: OBJECTIVE
  We investigated class switch reaction (CSR) in affected organs and evaluated whether the same or genetically related clones exist in IgG4-RD.
  
  
  METHODS
  We studied three patients with IgG4-RD. Total cellular RNA was extracted from salivary glands and peripheral blood and lung tissue. Activation-induced cytidine deaminase (AID) and immunoglobulin heavy chain third complementarity determining region (IgVH-CDR3) of IgM and IgG4 were detected by reverse transcription polymerase chain reaction (RT-PCR). We analyzed the clonal relationship of infiltrating IgG4-positive cells, as compared with IgM. We determined the existence of common clones among organs and patients.
  
  
  RESULTS
  AID was expressed in salivary glands of all patients and lung tissue in one. Closely related IgVH-CDR3 sequences in infiltrating IgG4-positive cells were detected in salivary glands and lung tissue. Identical IgVH-CDR3 sequence between IgM and IgG4 in salivary glands was detected in one patient, indicating CSR in salivary glands. Identical IgVH-CDR3 sequences of IgG4-positive cells were detected between salivary glands and peripheral blood in two patients. Four identical sequences of IgVH-CDR3 existed between patients. Interestingly, one of the four sequences was detected in all patients.
  
  
  CONCLUSIONS
  Our results demonstrate the existence of common antigen(s) shared by patients with IgG4-RD.
authors.affiliation: a Division of Rheumatology and.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kakuchi
authors.affiliation: a Division of Rheumatology and.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Yamada
authors.affiliation: a Division of Rheumatology and.
authors.forename: Kiyoaki
authors.initials: K
authors.lastname: Ito
authors.affiliation: a Division of Rheumatology and.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hara
authors.affiliation: a Division of Rheumatology and.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Fujii
authors.affiliation: b Division of Cardiology, Department of Internal Medicine , Kanazawa University Graduate School of Medicine , Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Yamagishi
authors.affiliation: a Division of Rheumatology and.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Kawano
mesh_terms: D000368:Aged; D001327:Autoimmune Diseases / Q000235:genetics / Q000276:immunology*; D003564:Cytidine Deaminase / Q000378:metabolism; D005260:Female; D006801:Humans; D017578:Immunoglobulin Class Switching; D007074:Immunoglobulin G / Q000235:genetics / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012469:Salivary Glands / Q000276:immunology*
chemical_list: D007074:Immunoglobulin G; D003564:Cytidine Deaminase
keywords: CDR3; Common antigen; IgG4-related disease