Regulatory T Cell - Regulatory T Cell Populations

Regulatory T Cell Populations

T regulatory cells are a component of the immune system that suppress immune responses of other cells. This is an important "self-check" built into the immune system to prevent excessive reactions. Regulatory T cells come in many forms with the most well-understood being those that express CD4, CD25, and Foxp3 (CD4+CD25+ regulatory T cells, or "T_regs"). These cells are involved in shutting down immune responses after they have successfully eliminated invading organisms, and also in preventing autoimmunity.

CD4+Foxp3+ regulatory T cells have been called "naturally-occurring" regulatory T cells to distinguish them from "suppressor" T cell populations that are generated in vitro. Additional suppressor T cell populations include Tr1, Th3, CD8+CD28-, and Qa-1 restricted T cells. The contribution of these populations to self-tolerance and immune homeostasis is less well defined. FOXP3 can be used as a good marker for CD4+CD25+ T cells as well as recent studies showing evidence for FOXP3 in CD4+CD25- T cells. An additional regulatory T cell subset, induced regulatory T cells, are also needed for tolerance and suppression.