Longterm maintenance of human naive T cells through in situ homeostasis in lymphoid tissue sites.
Level 4 - case-series / case-control
Cross-sectional post-mortem human tissue series
PubMed 28361127 · doi:10.1126/sciimmunol.aah6506
What was done
Researchers analyzed human naive T-cell development and maintenance across primary (thymus) and secondary (spleen, lymph nodes) lymphoid tissues obtained from organ donors aged 3 months to 73 years. They evaluated double-positive thymocyte frequencies, recent thymic emigrants, and TCR clonal repertoire diversity via CDR3 sequencing of naive CD4+ and CD8+ T cells across different anatomical sites.
What was found
No quantitative numbers, percentages, or statistical metrics were reported in the abstract. Qualitatively, double-positive thymocyte frequency declined sharply in donors over age 40, coincident with reduced recent thymic emigrants. Naive T cells were functionally maintained predominantly in lymph nodes. In donors older than 40 years, naive CD4+ and CD8+ T cells exhibited site-specific clonal expansions with minimal clonal overlap between lymphoid tissues and biased VJ usage within specific lymph nodes.
Why it matters
This study demonstrates that human naive T cells can persist through localized homeostatic maintenance and retention within secondary lymphoid tissues after age-associated thymic decline, rather than relying solely on ongoing thymic output.
Limits
The total sample size (n) of organ donors is not reported in the abstract. The study relies on cross-sectional post-mortem donor tissues rather than longitudinal follow-up, and the abstract omits all numerical values, effect sizes, and precision measures.
Cited by
- context Naive T cells have an estimated lifespan of 10 to 15 years in humans.