The influence of age on T cell generation and TCR diversity

Keith Naylor, Guangjin Li, Abbe N. Vallelo, Won Woo Lee, Kerstin Koetz, Ewa Bryl, Jacek Witkowski, James Fulbright, Cornelia M. Weyand, Jörg J. Goronzy

Research output: Contribution to journalArticlepeer-review

528 Scopus citations

Abstract

The ability to mount protective immune responses depends on the diversity of T cells. T cell diversity may be compromised by the declining thymic output of new T cells. The aging process imposes a threat to diversity, because thymic function deteriorates. In this study we have examined the relationship between thymic production, homeostatic T cell proliferation and TCR β-chain diversity in young (∼25 years), middle-aged (∼60 years), and elderly adults (∼75 years). TCR excision circles (TREC) as a marker of thymic output exponentially decreased by >95% between 25 and 60 years of age. The frequency of Ki67+ cycling CD4 T cells remained steady, and surprisingly, the diversity of the naive CD4 T cell repertoire was maintained at ∼2 × 107 different TCR β-chains. After the age of 70 years, TRECs only slightly declined, but homeostatic proliferation doubled. The diversity of the T cell pool drastically contracted to 200,000 TCR β-chains. Also, the phenotypic distinction between naive and memory CD4 T cells became fuzzy. The collapse in CD4 T cell diversity during the seventh and eighth decades indicates substantial T cell loss and implies that therapeutic measures to improve vaccine responses will have to include strategies for T cell replenishment.

Original languageEnglish (US)
Pages (from-to)7446-7452
Number of pages7
JournalJournal of Immunology
Volume174
Issue number11
DOIs
StatePublished - Jun 1 2005

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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