Restoration of T-cell homeostasis after T-cell depletion.
T-cell homeostasis appears to be maintained throughout much of normal adult life independent of de-novo production from hematopoietic stem cells via thymopoiesis. Instead, peripheral mechanisms are generally sufficient to maintain normal T-cell number, function and adequate TCR repertoire diversity in healthy hosts. Studies of T-cell regeneration in animals, however, have shown that full restoration of T-cell homeostasis after profound T-cell depletion is primarily dependent upon thymopoiesis. In this setting, thymic-deficient hosts have prolonged reductions in total T-cell number, restricted TCR repertoire diversity, and limited immunocompetence. In humans, age-related reductions in thymic regenerative capacity as early as young adulthood result in incomplete restoration of T-cell homeostasis after T-cell depletion.
Mackall
C L
CL
Pediatric Oncology Branch, National Cancer Institute, Bethesda, MD 20892, USA.
Hakim
F T
FT
Gress
R E
RE
D000328:Adult; D000818:Animals; D001854:Bone Marrow Cells / Q000276:immunology; D002648:Child; D006706:Homeostasis; D006801:Humans; D008212:Lymphocyte Depletion; D051379:Mice; D018448:Models, Immunological; D012038:Regeneration; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology*; D013950:Thymus Gland / Q000276:immunology