Central tolerance is impaired in the middle-aged thymic environment

Jessica N. Lancaster, Damaris E. Keatinge-Clay, Jayashree Srinivasan, Yu Li, Hilary J. Selden, Seohee Nam, Ellen R. Richie, Lauren I.R. Ehrlich

Research output: Contribution to journalArticlepeer-review


One of the earliest hallmarks of immune aging is thymus involution, which not only reduces the number of newly generated and exported T cells, but also alters the composition and organization of the thymus microenvironment. Thymic T-cell export continues into adulthood, yet the impact of thymus involution on the quality of newly generated T-cell clones is not well established. Notably, the number and proportion of medullary thymic epithelial cells (mTECs) and expression of tissue-restricted antigens (TRAs) decline with age, suggesting the involuting thymus may not promote efficient central tolerance. Here, we demonstrate that the middle-aged thymic environment does not support rapid motility of medullary thymocytes, potentially diminishing their ability to scan antigen presenting cells (APCs) that display the diverse self-antigens that induce central tolerance. Consistent with this possibility, thymic slice assays reveal that the middle-aged thymic environment does not support efficient negative selection or regulatory T-cell (Treg) induction of thymocytes responsive to either TRAs or ubiquitous self-antigens. This decline in central tolerance is not universal, but instead impacts lower-avidity self-antigens that are either less abundant or bind to TCRs with moderate affinities. Additionally, the decline in thymic tolerance by middle age is accompanied by both a reduction in mTECs and hematopoietic APC subsets that cooperate to drive central tolerance. Thus, age-associated changes in the thymic environment result in impaired central tolerance against moderate-avidity self-antigens, potentially resulting in export of increasingly autoreactive naive T cells, with a deficit of Treg counterparts by middle age.

Original languageEnglish (US)
Article numbere13624
JournalAging Cell
Issue number6
StatePublished - Jun 2022


  • T cell
  • cellular immunology
  • central tolerance
  • immune aging
  • thymus involution

ASJC Scopus subject areas

  • Aging
  • Cell Biology


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