An immunohistochemical and immunoelectron microscopic study of adhesion molecules in synovial pannus formation in rheumatoid arthritis

Rheumatol Int. 1996;16(2):53-60. doi: 10.1007/BF01816436.


To investigate the mechanism of synovial pannus formation in rheumatoid arthritis, immunohistochemical and immunoelectron microscopic studies with monoclonal antibodies against the adhesion molecules, CD54 (ICAM-1), CD11a (LFA-1), CDw49a (VLA-1), CDw49b (VLA-2), CDw49c (VLA-3), Cdw49d (VLA-4) and CDw49e (VLA-5), were carried out to determine the pattern of distribution of these molecules at the rheumatoid synovial cartilage junction. Treatment with anti-ICAM-1 resulted in membrane staining of most of the macrophages and fibroblasts infiltrating the synovial tissue and bordering and pannus-cartilage junction, suggesting the possibility that ICAM-1 may function to facilitate the adhesion of synovial type A cells bearing ICAM-1 to type B cells of the pannus. ICAM-1 positive macrophages and fibroblasts were often found to be in contact with lymphoid cells, suggesting also that a cellular immune reaction occurs in the formation of the pannus. In addition, VLA-3, VLA-4 and, particularly, VLA-5 were the predominant beta 1 integrins expressed by rheumatoid synovial pannus. Sine these three integrins all function as fibronectin receptors, it is possible that the fibronectin-rich environment of the rheumatoid cartilage surface effectively traps pannus cells expressing high levels of these molecules. The VLA-5 molecule was found in a pericellular and interterritorial matrix distribution in the present study, strongly suggesting that a receptor-ligand interaction between VLA-5 and cartilage matrix may occur at the early stage of pannus formation. Furthermore, an increase in beta 1 integrin may be necessary for the growth of the pannus and also for the upregulation of the VLA molecules, leading secondarily to increased attachment.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Antibodies, Monoclonal
  • Arthritis, Rheumatoid / metabolism*
  • Arthritis, Rheumatoid / pathology
  • Cartilage, Articular / metabolism*
  • Cartilage, Articular / ultrastructure
  • Female
  • Fibroblasts / metabolism
  • Fibroblasts / ultrastructure
  • Humans
  • Immunohistochemistry
  • Integrins / metabolism*
  • Intercellular Adhesion Molecule-1 / metabolism*
  • Macrophages / metabolism
  • Macrophages / ultrastructure
  • Male
  • Microscopy, Immunoelectron
  • Middle Aged
  • Synovial Membrane / metabolism*
  • Synovial Membrane / ultrastructure


  • Antibodies, Monoclonal
  • Integrins
  • Intercellular Adhesion Molecule-1