Continued maturation of thymic emigrants in the periphery

Nat Immunol. 2004 Apr;5(4):418-25. doi: 10.1038/ni1049. Epub 2004 Feb 29.


Developing thymocytes are selected for recognition of molecules encoded by the major histocompatibility complex, purged of self-reactive cells and committed to either the CD4 or CD8 lineage. The 1% of thymocytes that complete these tasks emigrate and join the population of peripheral lymphocytes. Whether T cell maturation is complete at the time of thymic exit has been a subject of debate. Using mice transgenic for green fluorescent protein driven by the recombination activating gene 2 promoter to identify recent thymic emigrants, we now show that T cell differentiation continues post-thymically, with progressive maturation of both surface phenotype and immune function. In addition, the relative contribution of CD4 and CD8 recent thymic emigrants was modulated as they entered the peripheral T cell pool. Thus, T cell maturation and subset contribution are both finalized in the lymphoid periphery.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • CD4-CD8 Ratio
  • CD4-Positive T-Lymphocytes / physiology
  • CD8-Positive T-Lymphocytes / physiology
  • Cell Differentiation / physiology*
  • Cell Movement / physiology*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / physiology
  • Genes, Reporter
  • Mice
  • Mice, Transgenic
  • Thymus Gland / cytology
  • Thymus Gland / physiology*
  • Time Factors


  • DNA-Binding Proteins
  • Rag2 protein, mouse
  • V(D)J recombination activating protein 2