Life span of naive and memory T cells.
The life span of mature T cells is reviewed. Peripheral T lymphocytes are a heterogeneous population and comprise a mixture of naive, effector and memory cells. The recirculating pool of mature T cells is formed during young life through gradual release of naive T cells from the thymus. In adults, the pool of mature T cells is relatively self-sufficient, and input of new T cells from the thymus declines to low levels. Studies on T cell turnover indicate that most peripheral T cells can remain in a resting state for long periods (months in rodents and years in humans). Examination of the phenotype of dividing versus nondividing cells suggests that typical naive T cells are long-lived resting cells whereas the majority of effector and memory T cells have a much more rapid turnover. However, some memory T cells appear to divide very infrequently and eventually return to a resting state. The factors controlling the generation and maintenance of memory T cells are discussed.
Tough
D F
DF
Department of Immunology, Scripps Research Institute, La Jolla, California 92037, USA.
Sprent
J
J
D000818:Animals; D002470:Cell Survival; D006801:Humans; D007156:Immunologic Memory / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology