CD4 and rheumatoid arthritis: DCs in situ are often surrounded by a cluster of T cells [7] and are thought to internalize autoantigens from the extracellular matrix and cartilage for intracellular processing and presentation of arthritogenic epitopes to specific CD4 T cells, as well as to induce activation of B lymphocytes in patients with rheumatoid arthritis (RA) [8].