Aging and T-cell diversity.
Naïve and memory CD4 and CD8 T cells constitute a highly dynamic system with constant homeostatic and antigen-driven proliferation, influx, and loss of T cells. Thymic activity dwindles with age and essentially ceases in the later decades of life, severely constraining the generation of new T cells. Homeostatic control mechanisms are very effective at maintaining a large and diverse subset of naïve CD4 T cells through the 7th decade of life, but eventually and abruptly fail at about the age of 75 years. In contrast, the CD8 T cell compartment is more unstable, with progressive diminution of naïve T cells and increasing loss of diversity during mid adulthood. Vaccination strategies need to aim at developing a broad repertoire of memory T cells before the critical time period when the naïve CD4 T-cell repertoire collapses. Research efforts need to aim at understanding T-cell homeostatic control mechanisms to ultimately expand the time period of repertoire stability.
Goronzy
Jörg J
JJ
Lowance Center for Human Immunology, Emory University School of Medicine, 101 Woodruff Circle #1003, Atlanta, GA 30322, USA. jgoronz@emory.edu
Lee
Won-Woo
WW
Weyand
Cornelia M
CM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D006706:Homeostasis; D006801:Humans; D007156:Immunologic Memory; D008875:Middle Aged; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
D011948:Receptors, Antigen, T-Cell