title: Expression of BAFF and BAFF-R in the synovial tissue of patients with rheumatoid arthritis.
abstract: OBJECTIVE
  The elevated expression of B-cell-activating factor belonging to the TNF family (BAFF) is associated with systemic autoimmune disease, including rheumatoid arthritis (RA). The present study was undertaken to determine the distribution of BAFF and its receptor BAFF-R in the cells residing in the rheumatoid synovium.
  
  
  METHODS
  The expression of BAFF and BAFF-R in synovial tissues obtained from 12 RA patients was examined by immunohistochemistry and flow cytometry. The mRNA expression of these molecules was determined by reverse transcriptase polymerase chain reaction (RT-PCR). Soluble BAFF levels were measured with an enzyme-linked immunosorbent assay (ELISA). Fibroblast-like synoviocytes (FLS) purified from the RA (RA-FLS) were co-cultured with peripheral B cells. The degree of apoptosis in the B cells was measured to assess the effects on the viability of the B cells.
  
  
  RESULTS
  The RA synovium showed focal or diffuse infiltration of mononuclear cells (MNCs), and one specimen showed germinal centre (GC)-like structures. Synovial sublining cells, but not lining cells, expressed BAFF. These sublining cells were negative for BAFF-R. BAFF and BAFF-R were expressed in B and T cells extracted from the RA synovium. Notably, RA-FLS spontaneously expressed cytoplasmic BAFF after 4-6 passages; however, they did not express BAFF or BAFF-R on their cell surface. RA-FLS could support the survival of B cells by preventing their apoptosis, but its effect on B cells might not be BAFF dependent.
  
  
  CONCLUSIONS
  BAFF and BAFF-R are widely expressed in the RA synovium. The cells residing in the RA synovium might affect each other through BAFF.
authors.affiliation: Division of Rheumatic Diseases, International Medical Centre of Japan, Tokyo.
authors.forename: K
authors.initials: K
authors.lastname: Nakajima
authors.forename: K
authors.initials: K
authors.lastname: Itoh
authors.forename: K
authors.initials: K
authors.lastname: Nagatani
authors.forename: M
authors.initials: M
authors.lastname: Okawa-Takatsuji
authors.forename: T
authors.initials: T
authors.lastname: Fujii
authors.forename: H
authors.initials: H
authors.lastname: Kuroki
authors.forename: Y
authors.initials: Y
authors.lastname: Katsuragawa
authors.forename: S
authors.initials: S
authors.lastname: Aotsuka
authors.forename: A
authors.initials: A
authors.lastname: Mimori
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015703:Antigens, CD / Q000032:analysis; D001172:Arthritis, Rheumatoid / Q000235:genetics* / Q000473:pathology; D053264:B-Cell Activating Factor / Q000235:genetics*; D053265:B-Cell Activation Factor Receptor / Q000235:genetics*; D002097:C-Reactive Protein / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013583:Synovial Membrane / Q000473:pathology
chemical_list: D015703:Antigens, CD; D053264:B-Cell Activating Factor; D053265:B-Cell Activation Factor Receptor; C435926:TNFRSF13C protein, human; C505719:TNFSF13B protein, human; D002097:C-Reactive Protein