Regulatory T cells for immunological tolerance and immune homeostasis (LL4-4)

Naturally arising CD25+CD4+ regulatory T cells (Tregs), which specifically express the transcription factor Foxp3, are engaged in the maintenance of immunological self-tolerance and immune homeostasis. They suppress aberrant or excessive immune responses, such as autoimmune disease and allergy. They are also exploited to enhance tumor immunity or establish transplantation tolerance. Foxp3 controls key functional features of Tregs: its expression is sufficient to confer suppressive activity to naive T cells, repress production of cytokines such as interleukin-2 (IL-2) and interferon-gamma (IFN-γ), and up-regulate Treg-associated molecules such as CD25, and cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4). Our current understanding will be discussed on how Foxp3+ Tregs are generated, how they exert suppression, and how they can be exploited at the molecular level to control immune responses in a variety of clinical settings.