Rheumatoid arthritis (RA) is the most common and most severe form of i nflammatory arthritis. The pathogenesis of RA has been the subject of intense research for several decades. The prevailing hypotheses have c hanged over the years, and have attempted to incorporate the most rece nt data. Although T cells represent an important component of the cell s that infiltrate the joint synovium, their contribution at a late sta ge of the disease remains a matter of debate.