Light microscopic characterization of the fibroblast-like synovial intimal cell (synoviocyte)

Arthritis Rheum. 1992 Oct;35(10):1179-84. doi: 10.1002/art.1780351010.


Objective: To reassess synovial intimal cell populations by light microscopy.

Methods: Non-inflamed, rheumatoid and osteoarthritic synovia were analyzed as tissue sections and cytospin preparations by a series of combined immunohistochemical and cytochemical staining techniques.

Results: Two populations of intimal cells were identified. The first carried macrophage markers. The second showed high uridine diphosphoglucose dehydrogenase (UDPGD) activity, minimal cytoplasmic CD68, absent non-specific esterase (NSE) activity, and absent leukocyte and endothelial antigens. The majority of these cells showed a high content of prolyl hydroxylase.

Conclusion: Combined cytochemical staining for NSE and UDPGD activity allows effective separation of intimal cell populations. We suggest that the cells of high UDPGD activity are the fibroblast-like or type B synovial intimal cells defined by electron microscopy. High UDPGD activity probably reflects a preferential ability to synthesize glycosaminoglycans, including hyaluronan.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, CD / metabolism
  • Antigens, Differentiation, Myelomonocytic / metabolism
  • Arthritis, Rheumatoid / enzymology
  • Arthritis, Rheumatoid / immunology
  • Arthritis, Rheumatoid / pathology
  • Esterases / metabolism
  • Fibroblasts / enzymology
  • Fibroblasts / pathology
  • Humans
  • Immunohistochemistry
  • Macrophages / immunology
  • Macrophages / pathology
  • Osteoarthritis / enzymology
  • Osteoarthritis / immunology
  • Osteoarthritis / pathology
  • Procollagen-Proline Dioxygenase / metabolism
  • Synovial Membrane / enzymology
  • Synovial Membrane / immunology
  • Synovial Membrane / pathology*
  • Uridine Diphosphate Glucose Dehydrogenase / metabolism


  • Antigens, CD
  • Antigens, Differentiation, Myelomonocytic
  • CD68 antigen, human
  • Uridine Diphosphate Glucose Dehydrogenase
  • Procollagen-Proline Dioxygenase
  • Esterases