T-cell-mediated control of autoimmunity

Inflammatory responses provoked by pathogens are antigen-specific in their induction but are nonspecific in their effects. Consequently, they are potentially damaging to the host that produces them. In addition, the immune system can respond specifically to self antigens, thereby giving rise to autoimmune diseases. A number of regulatory mechanisms have evolved to prevent such adverse effects. One of these has been shown to depend on a particular subset of CD4(+) T cells that appears to have evolved specifically for this protective role. These cells are termed regulatory T cells. This review summarises what is known about them.