Hakim FT, Memon SA, Cepeda R, Jones EC, Chow CK, Kasten-Sportes C, Odom J, Vance BA, Christensen BL, Mackall CL, Gress RE. Age-dependent incidence, time course, and consequences of thymic renewal in adults.
J Clin Invest 2005;
115:930-9. [PMID:
15776111 PMCID:
PMC1064981 DOI:
10.1172/jci22492]
[Citation(s) in RCA: 155] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Accepted: 01/25/2005] [Indexed: 11/17/2022] Open
Abstract
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 Vbeta 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.
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