Although the cause of rheumatoid arthritis (RA) remains unknown, insights into the
pathogenesis of RA have been achieved by careful study of inflammatory, immune, and
tissue-destructive processes that take place in synovial tissue. Successful approaches have
included ex vivo analysis of RA synovium, experiments in animal model systems, and use of
cultured cell lines, especially fibroblast-like synoviocytes, derived from patients' synovial
tissue. These insights have led to remarkable advances in the treatment of RA and other …