Monoclonal expansion of synoviocytes in rheumatoid arthritis

Arthritis Rheum. 1998 Nov;41(11):1979-86. doi: 10.1002/1529-0131(199811)41:11<1979::AID-ART13>3.0.CO;2-C.


Objective: To examine whether synoviocytes from patients with rheumatoid arthritis (RA) have a stronger growth ability than those from patients with osteoarthritis (OA), and to determine whether these synoviocytes clonally expand in situ.

Methods: Synovial tissues from 13 RA patients and 4 OA patients were cultured, and their ability to form colonies in soft agarose was examined. RA and OA synoviocytes were also examined in varying concentrations of fetal calf serum (FCS)-containing medium to test the effects of FCS on colony formation. DNA was extracted from clones with colony-forming ability in nonpannus lesions and from synoviocytes in pannus lesions. Restriction fragment length polymorphism (RFLP) analysis was used to examine phosphoglycerate kinase 1 (PGK-1) gene patterns. Production of cytokines by these cells was also assessed.

Results: All 13 RA synoviocytes exhibited colony formation, whereas none of the 4 OA synoviocytes did. This tendency was also seen with all of the concentrations of FCS examined, although growth varied in a dose-dependent manner. In contrast to OA synovial clones, cloned RA synoviocytes obtained from colonies exhibited a partial RFLP PGK-1 gene pattern, suggesting that the clones originated from monoclonal cells. Of note, 3 of 7 noncloned synoviocytes from pannus lesions exhibited a monoclonal pattern. Pannus cells produced high levels of transforming growth factor beta and platelet-derived growth factor.

Conclusion: These findings suggest that synoviocytes with a strong growth ability are present in the rheumatoid synovium, and that these cells expand monoclonally, particularly in pannus lesions.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Arthritis, Rheumatoid / immunology*
  • Arthritis, Rheumatoid / metabolism
  • Arthritis, Rheumatoid / pathology*
  • Cartilage / immunology
  • Cartilage / metabolism
  • Cartilage / pathology
  • Cell Division / physiology
  • Clone Cells
  • Gene Expression Regulation, Enzymologic / immunology
  • Humans
  • Hyperplasia
  • Male
  • Middle Aged
  • Osteoarthritis / immunology
  • Osteoarthritis / metabolism
  • Osteoarthritis / pathology
  • Phosphoglycerate Kinase / genetics
  • Platelet-Derived Growth Factor / immunology
  • Platelet-Derived Growth Factor / metabolism
  • Polymorphism, Restriction Fragment Length
  • Stem Cells / cytology
  • Synovial Membrane / cytology*
  • Synovial Membrane / enzymology
  • Synovial Membrane / immunology*
  • Transforming Growth Factor beta / immunology
  • Transforming Growth Factor beta / metabolism


  • Platelet-Derived Growth Factor
  • Transforming Growth Factor beta
  • Phosphoglycerate Kinase