Role of antigen presenting cells in rheumatoid arthritis.

Histological evidence indicates that activated antigen presenting cells (APC) are present in large numbers within the synovial compartment in rheumatoid arthritis. Their potent function has been demonstrated in vitro using isolated synovial APC populations, although the full picture of which APC populations are involved is still emerging. The ability of these APC to activate T cells which traffic to the joint is likely to play an important role in the maintenance of the synovial inflammatory response.