ABSTRACT
Rheumatic diseases cover a wide range of different pathological entities. Plasma levels do not rise in most inflammatory diseases, and studies in rheumatoid arthritis have invariably shown concentrations to be normal. By contrast, synovial fluid fibronectin levels are significantly elevated in comparison to plasma. Fibronectin from different sources is known to have biochemical differences due to posttranslational modifications. There has been one reported clinical study showing a correlation between clinical improvement and synovial fluid fibronectin levels in arthritic patients treated with orgotein. Rice bodies are particulate material of variable size found in the synovial fluid of most patients with rheumatoid effusions. The distribution of fibronectin in the synovial membrane and pannus has been extensively studied using immunohistology with both indirect immunofluorescence and immunoperoxidase methods and also immunoelectron-microscopy. The concept that fibronectin may be involved in immune complexes stems from its known opsonic role.
