Basic mechanisms in rheumatoid arthritis: the role of T lymphocytes in rheumatoid synovitis

Undoubtedly, synovitis is a cell-mediated process involving various cell types, such as T cells, B cells, APC, monocytes/macrophages, synoviocytes, chondrocytes, and cytokines. Therefore, it is difficult to clarify the cell type that plays the central role in the inflammatory process. Despite this difficulty, there is strong evidence that T cells mediate the disease in collaboration with APC that bear specific antigenic peptides. The mediators released could perpetuate an ongoing inflammatory process in the joints irrespective of the nature of the initiating agents. Therefore, many approaches to a more specific immunotherapy for RA have been developed, directed toward the modulation of T cell function. Thus far, various forms of chemical and biologic treatment have been used, such as cyclosporin A and monoclonal antibodies directed against T-cell epitopes and IL-2 receptor, with some beneficial effects on the course of RA. The development of a more specific immunotherapy using reagents directed against the T-cell receptor and vaccination with specific T cells await further studies, since we still do not know the inciting antigen(s) in RA. Nevertheless, we are hopeful that the ongoing search for the still unknown antigen(s) will be successful, thus providing new and better treatment regimens for a still uncurable disease.