Objective: To assess the variability of synovial histology, immunohistology, and cytokine mRNA expression at different sites within the knee joints of subjects with rheumatoid arthritis receiving slow acting antirheumatic drugs. The effects of intraarticular bupivacaine and adrenaline, and a comparison of synovial fluid cell and synovial membrane cytokine expression, were also investigated.
Methods: Arthroscopically directed synovial biopsies were taken at 3 or 4 predetermined sites from the knee joints of 11 patients. Histology for synovial lining layer, sublining cellularity and vascularity, and immunohistology for T cells, T cell subsets, and macrophages were assessed. Messenger RNA expression of interleukins 1beta, 2, 4, 6, 8, 10, granulocyte-monocyte colony stimulating factor, tumor necrosis factor-alpha, and interferon-gamma was detected using the reverse transcription/polymerase chain reaction technique.
Results: Synovial histology, immunohistology, and cytokine mRNA expression did not vary significantly. CD8 cell immunohistology was variable. Intraarticular bupivacaine and adrenaline did not change synovial characteristics. Synovial fluid cell and membrane cytokine expression did not match in 35% of comparisons.
Conclusion: Biopsies from the suprapatellar pouch, medial gutter, and cartilage-pannus junction will provide a representative sample of synovial membrane pathology in patients with rheumatoid arthritis.