The role of T cells in rheumatoid arthritis: new subsets and new targets.
OBJECTIVE
To update the knowledge on the contribution of T cells in rheumatoid arthritis, a selection of publications between the end of 2005 and 2006 were reviewed.


RESULTS
Th17 cells driven by TGF-beta, IL-1, IL-6 and IL-23 challenge previous concepts of 'Th1'-induced rheumatoid arthritis. Other advancements in IL-17 studies include novel concepts on the IL-17 receptor and additional information on the mechanism of IL-17-induced effects. Regulatory T cells fail to control disease due to defective function secondary to the synovial inflammatory milieu. The predominance of pathogenic effector T cells in the presence of impaired T-cell regulatory mechanisms may therefore contribute to rheumatoid arthritis chronicity. Cellular therapies attempt to restore the balance that includes production of immunoregulatory cytokines such as IL-4 or IL-10. Better T-cell-targeted therapies controlling costimulation are in place with purported increased efficacy and durability, including anti-tumour necrosis factor nonresponders. Additional direct and indirect T-cell approaches include antagonism of T-cell-derived cytokines, T-cell activation or B-cell ablation.


CONCLUSIONS
A renewed interest in T cells comes from the discovery of Th17 in rheumatoid arthritis and from novel findings on the role of T cells in rheumatoid arthritis induction, chronicity and relapse.
Toh
Myew-Ling
ML
Department of Immunology and Rheumatology, Hôpital Edouard Herriot, Lyon, France.
Miossec
Pierre
P
D019264:Adoptive Transfer; D000818:Animals; D001169:Arthritis, Experimental / Q000276:immunology / Q000628:therapy; D001172:Arthritis, Rheumatoid / Q000276:immunology* / Q000628:therapy; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D006801:Humans; D016219:Immunotherapy, Adoptive; D007371:Interferon-gamma / Q000378:metabolism; D020381:Interleukin-17 / Q000378:metabolism; D051379:Mice; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology
D020381:Interleukin-17; D007371:Interferon-gamma