Control of T cell viability.
The factors affecting T cell viability vary depending on the type and status of the T cell involved. Naive T cells die via a Bcl-2/Bim dependent route. Their deaths are prevented in animals by IL-7 and contact with MHC. Activated T cells die in many different ways. Among these is a pathway involving signals that come from outside the T cell and affect it via surface receptors such as Fas. Activated T cells also die through a pathway driven by signals generated within the T cell itself, a cell autonomous route. This pathway involves members of the Bcl-2 family, in particular Bcl-2, Bcl-xl, Bim, and probably Bak. The viability of CD8+ and CD4+ memory T cells is controlled in different ways. CD8+ memory T cells are maintained by IL-15 and IL-7. The control of CD4+ memory T cells is more mysterious, with roles reported for IL-7 and/or contact via the TCR.
Marrack
Philippa
P
Howard Hughes Medical Institute and Integrated Department of Immunology, National Jewish Medical and Research Center, and Department of Medicine, University of Colorado Health Sciences Center, Denver, Colorado 80206, USA. marrackp@njc.org
Kappler
John
J
D000818:Animals; D016923:Cell Death / Q000276:immunology; D002470:Cell Survival / Q000276:immunology; D006801:Humans; D007156:Immunologic Memory; D008213:Lymphocyte Activation / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology*; D013601:T-Lymphocytes / Q000502:physiology*