Molecular mechanisms of activated T cell death in vivo.

The culmination of the immune response involves the death of the majority of the activated antigen-specific T lymphocytes. The death of these cells is important to prevent autoimmunity, to decrease the metabolic cost to the organism and to ensure T cell homeostasis. This review will focus on the mechanisms that, in animals, control the death of these activated cells. At least two separate types of cell death can occur (activation-induced cell death and activated T cell autonomous death) via death receptors such as Fas or the Bcl-2 related protein Bim, respectively. Finally, adjuvants that enable T cell survival may operate via NF-kappaB and Bcl-3 rather than cytokines.