Effector T cells in rheumatoid arthritis: Lessons from animal models

The development of an immune response to self antigens drives naive T cells to differentiate into subsets of CD8 ⁺ and CD4 ⁺ effector cells including T _H1, T _H2, cells and the more recently described T _H17, and regulatory T cells (T _reg). Rheumatoid arthritis is an autoimmune disease that engages an uncontrolled influx of inflammatory cells to the joints, eventually leading to joint damage. The role that effector T cells play in the local or systemic maintenance of, or protection against, inflammation and subsequent joint damage is now becoming better understood through the use of animal models. In this review, we will explore the different animal models of RA, and their contribution to elucidating the role that effector T cells play in the regulation, induction, and maintenance of inflammatory joint disease. This understanding will aid in the design of more effective therapeutic strategies for rheumatoid arthritis and other autoimmune disorders.