Thymopoiesis independent of common lymphoid progenitors

Nat Immunol. 2003 Feb;4(2):168-74. doi: 10.1038/ni878. Epub 2003 Jan 6.


Early T lineage progenitors (ETPs) in the thymus are thought to develop from common lymphoid progenitors (CLPs) in the bone marrow (BM). We compared thymic ETPs to BM CLPs in mice and found that they differed in several respects. Thymic ETPs were not interleukin 7 (IL-7)-responsive and generated B lineage progeny with delayed kinetics, whereas BM CLPs were IL-7-responsive and rapidly generated B cells. ETPs sustained production of T lineage progeny for longer periods of time than BM CLPs. Analysis of Ikaros-deficient mice that exhibit ongoing thymopoiesis without B lymphopoeisis revealed near-normal frequencies of thymic ETPs, yet undetectable numbers of BM CLPs. We conclude that ETPs can develop via a CLP-independent pathway.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • B-Lymphocytes / cytology
  • B-Lymphocytes / immunology
  • Bone Marrow Cells / cytology
  • Bone Marrow Cells / immunology
  • DNA-Binding Proteins*
  • Female
  • Gene Rearrangement, beta-Chain T-Cell Antigen Receptor
  • Hematopoietic Stem Cells / cytology*
  • Hematopoietic Stem Cells / immunology*
  • Ikaros Transcription Factor
  • Interleukin-7 / pharmacology
  • Kinetics
  • Lymphopoiesis* / drug effects
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • T-Lymphocytes / cytology*
  • T-Lymphocytes / drug effects
  • T-Lymphocytes / immunology*
  • Thymus Gland / cytology
  • Thymus Gland / immunology
  • Transcription Factors / deficiency
  • Transcription Factors / genetics
  • Transcription Factors / immunology


  • DNA-Binding Proteins
  • Interleukin-7
  • Transcription Factors
  • Zfpn1a1 protein, mouse
  • Ikaros Transcription Factor