Synovial localization of tumor necrosis factor in patients with rheumatoid arthritis

Tissue localization of tumor necrosis factor (TNF alpha) was examined in synovial tissues from 10 patients with active rheumatoid arthritis (RA) and three osteoarthritis controls using both monoclonal and polyclonal antibodies to TNF alpha and immunoperoxidase technique. No prominent staining for TNF alpha was noted in any of the osteoarthritis non-inflammatory synovial samples; however, six out of 10 RA synovial tissues displayed strongly positive tissue distribution of TNF alpha epitopes particularly within synovial lining cells, and interstitial monocyte/macrophage cells within inflammatory infiltrates. The amounts of TNF alpha visualized within synovial lining cells appeared to parallel the extent of inflammatory cell collections within the rheumatoid synovial tissues examined. Similar studies using renal biopsy tissues from seven patients with Systemic Lupus Erythematosus (SLE) nephritis (including diffuse proliferative nephritis, nephrotic syndrome, focal glomerulonephritis, and membranous nephritis) showed no tissue localization of TNF alpha. These findings emphasize that a potent lymphokine (TNF alpha), which may be important in the underlying inflammatory process, appears to be localized and perhaps produced by synovial lining cells within active RA synovial tissues.