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Stochastic coreceptor shut-off is restricted to the CD4 lineage maturation pathway

B Lucas1, F Vasseur, C Penit

  • 1Unité 345 Institut de la Santé et de la Recherche Médicale, CHU Necker-Enfants, Paris, France.

The Journal of Experimental Medicine
|May 1, 1995
PubMed

Insights

Investigating T cell development in mice revealed distinct pathways for CD4+8- and CD4-8+ T cell generation. Major histocompatibility complex (MHC) deficiency impacts T cell maturation timing and commitment, highlighting asymmetrical differentiation processes.

Area of Science:

  • Immunology
  • Developmental Biology
  • T cell biology

Background:

  • T cell maturation in the thymus is crucial for adaptive immunity.
  • Major histocompatibility complex (MHC) molecules play a key role in T cell selection and development.
  • Understanding the kinetics and regulation of T cell subset generation is essential.

Purpose of the Study:

  • To investigate the kinetics of mature T cell generation in normal and MHC-deficient mice.
  • To elucidate the roles of MHC class I and II in T cell lineage commitment and differentiation.
  • To determine the distinct regulatory mechanisms governing CD4+8- and CD4-8+ T cell development.

Main Methods:

  • Bromodeoxyuridine (BrdU) pulse labeling to track cell proliferation and differentiation.
  • Flow cytometry analysis of T cell subsets (CD4, CD8) in thymic populations.
  • Analysis of T cell receptor (TCR) V beta 14 frequencies in different CD4/8 subsets.

Main Results:

  • T cell activation and maturation phases are synchronous, but generation rates differ between CD4+8- and CD4-8+ cells in MHC-deficient mice.
  • CD8 downregulation initiation is stochastic and can occur without MHC class II expression.
  • CD4 shut-off is instructive, with MHC class I deficiency preventing the generation of CD4lo8+ cells.
  • CD4 and CD8 generation pathways are asymmetrical, confirmed by TCR V beta 14 analysis.

Conclusions:

  • Commitment to the CD4+8- phenotype is regulated at the CD8lo stage.
  • Commitment to the CD4-8+ phenotype is regulated at the CD4+8+ double-positive stage.
  • MHC-deficient environments reveal distinct, asymmetrical control mechanisms in T cell lineage commitment.

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