Interleukin-7: master regulator of peripheral T-cell homeostasis?
Recent evidence has implicated interleukin-7 (IL-7) as a master regulator of T-cell homeostasis, based upon its essential role in the homeostatic expansion of naive T-cell populations in response to low-affinity antigens (Ags) and its capacity to enhance dramatically the expansion of peripheral T-cell populations in response to high-affinity Ags. Furthermore, T-cell-depleted humans have a unique inverse relationship between the peripheral CD4(+) T-cell count and the level of circulating IL-7. Together, these data suggest that increased amounts of IL-7 become available following T-cell depletion, thus, enhancing the high- and low-affinity Ag-driven expansion of the population of residual, mature T cells and boosting thymic regenerative capacity, as a means to restore T-cell homeostasis.
Fry
T J
TJ
Pediatric Oncology Branch, National Cancer Institute, National Institutes of Health, Building 10, Room 13N240, 10 Center Drive, MSC 1928, Bethesda, MD 20892-1928, USA.
Mackall
C L
CL
D000818:Animals; D006706:Homeostasis / Q000276:immunology; D006801:Humans; D015851:Interleukin-7 / Q000276:immunology*; D018655:Lymphocyte Count; D008212:Lymphocyte Depletion; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
D015851:Interleukin-7; D011948:Receptors, Antigen, T-Cell