Immunoregulatory T cells in autoimmunity

The aim of this work was to discuss the current knowledge concerning regulatory T cells in the pathogenesis of autoimmune diseases. CD4+ T cells that constitutively express CD25 exhibit powerful suppressive properties. Such cells have been denominated regulatory T cells (TR). Alterations in TR cells are known to cause organ-specific autoimmune disease in animal models. These cells are anergic when stimulated via their TCR but proliferate when costimulated with IL-2. A particular characteristic is that CD4+CD25+ T cells inhibit the proliferative responses of CD4+CD25− T cells by suppressing the capacity of the responders to transcribe IL-2. The survival and/or expansion of this regulatory subset in the periphery appears to need the availability of IL-2, the components of the IL-2R, as well as cell surface costimulatory molecules. Cytokine participation has been shown in many of the in vivo models of autoimmunity where regulatory cells participate, providing evidence in favour of a role for IL-10, transforming growth factor-β and IL-4. The behavior and possible participation of regulatory T cells in human disease is still a poorly explored topic but their pathogenic role is warranted.