TY - JOUR AU - Hakim, Frances T. AU - Memon, Sarfraz A. AU - Cepeda, Rosemarie AU - Jones, Elizabeth C. AU - Chow, Catherine K. AU - Kasten-Sportes, Claude AU - Odom, Jeanne AU - Vance, Barbara A. AU - Christensen, Barbara L. AU - Mackall, Crystal L. AU - Gress, Ronald E. T1 - Age-dependent incidence, time course, and consequences of thymic renewal in adults PY - 2005/04/01/ AB - Homeostatic regulation of T cells involves an ongoing balance of new T cell generation, peripheral expansion, and turnover. The recovery of T cells when this balance is disrupted provides insight into the mechanisms that govern homeostasis. In a long-term, single cohort study, we assessed the role of thymic function after autologous transplant in adults, correlating serial computed tomography imaging of thymic size with concurrent measurements of peripheral CD4+ T cell populations. We established the age-dependent incidence, time course, and duration of thymic enlargement in adults and demonstrated that these changes were correlated with peripheral recovery of naive CD45RA+CD62L+ and signal-joint TCR rearrangement excision circle–bearing CD4+ populations with broad TCR diversity. Furthermore, we demonstrated that renewed thymopoiesis was critical for the restoration of peripheral CD4+ T cell populations. This recovery encompassed the recovery of normal CD4+ T cell numbers, a low ratio of effector to central memory cells, and a broad repertoire of TCR Vβ diversity among these memory cells. These data define the timeline and consequences of renewal of adult thymopoietic activity at levels able to quantitatively restore peripheral T cell populations. They further suggest that structural thymic regrowth serves as a basis for the regeneration of peripheral T cell populations. JF - The Journal of Clinical Investigation JA - J Clin Invest SN - 0021-9738 DO - 10.1172/JCI22492 VL - 115 IS - 4 UR - https://doi.org/10.1172/JCI22492 SP - 930 EP - 939 PB - The American Society for Clinical Investigation ER -