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Examination of Thymic Positive and Negative Selection by Flow Cytometry
14:29

Examination of Thymic Positive and Negative Selection by Flow Cytometry

Published on: October 8, 2012

The majority of postselection CD4+ single-positive thymocytes requires the thymus to produce long-lived, functional T

R Dyall1, J Nikolić-Zugić

  • 1Laboratory of T Cell Development, Immunology Program, Memorial Sloan-Kettering Cancer Center, New York 10021.

The Journal of Experimental Medicine
|January 1, 1995
PubMed

Insights

Two late T cell subsets, CD8- and CD8lo, were studied. CD8- cells were functional, while CD8lo cells required the thymus for maturation into functional T cells.

Area of Science:

  • Immunology
  • T cell development
  • Thymocyte biology

Background:

  • Two subsets of CD4hi T cell receptor (TCR)hi single positive (SP) thymocytes, CD8- and CD8lo, were previously isolated.
  • These late thymocyte subsets were analyzed for their phenotypic, functional, and developmental characteristics.

Purpose of the Study:

  • To analyze the characteristics of CD8- and CD8lo late CD4hi SP thymocyte subsets.
  • To understand the role of the thymic microenvironment in T cell maturation.

Main Methods:

  • Phenotypic and functional analysis of thymocyte subsets.
  • In vitro T cell receptor (TCR) cross-linking assays.
  • Graft versus host disease (GVHD) induction assays.
  • Analysis of cell survival and expansion in peripheral lymphoid organs.

Main Results:

  • CD8-4hi thymocytes were functional, inducing GVHD, surviving and expanding in peripheral organs, and proliferating upon TCR cross-linking.
  • CD8lo4hi cells were non-functional, undergoing apoptosis upon TCR cross-linking and failing to induce GVHD or expand peripherally.
  • Reintroduction into the thymus allowed CD8lo4hi cells to mature into functional, long-lived CD8-4hi lymphocytes.

Conclusions:

  • The thymic microenvironment is essential for the final maturation of most CD4hi SP postselection thymocytes.
  • A previously unrecognized control point in T cell development exists, regulating the maturation of CD4hi SP thymocytes.

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