Presence of rheumatoid arthritis (RA) synovial autoantigen recognized by T cells in RA joints

The disease-specific antigen in rheumatoid arthritis (RA) is still unknown. Analyses of the T cell receptor (TCR) repertoire suggested that certain antigen-driven T cells infiltrate into the legion. Efforts to establish T cell lines or clones which recognize RA-specific antigen showed that multiple antigen-reactive T cells were detected in inflamed joints. These antigens fall in two categories, one is foreign antigens which induce molecular mimicry and the other is autoantigens. To date, few etiological studies have shown convincing relationships between RA and infectious diseases. Further, lymphocytes reactive to candidate RA autoantigens were often observed in other autoimmune patients. To determine the primary and RA-specific autoantigen, we focused on T cells specific for RA synovial nurse cells. In the present review, we summarize previous studies on tissue-infiltrating T cells in RA and our recent studies on RA synovial nurse cell-specific autoantigen recognized by T cell clones established from RA joints.