Immuno-electron microscopy of chondrocyte-derived cells in the rheumatoid cartilage-pannus junction.

Immuno-electron microscopy has been utilised to examine the cartilage-pannus junction in seven patients with rheumatoid arthritis. Using a monoclonal antibody, keratan sulphate was localised to cells with the ultra-structural appearance of fibroblasts within a transitional fibroblastic zone in the pannus in two cases. This confirms previous light microscopy evidence that this area (which is clearly separate from articular cartilage) contains cells which produce keratan sulphate, and strengthens the hypothesis that these cells are derived from cartilage rather than from the adjacent synovial membrane.