Positive selection of the T cell repertoire: where and when does it occur?

Cell. 1989 Sep 22;58(6):1027-33. doi: 10.1016/0092-8674(89)90501-1.


The T cell repertoire is shaped by both positive and negative influences. T lymphocytes that express the V beta 6 variable region are positively selected in the thymus by cells expressing major histocompatibility complex (MHC) class II E molecules. To identify these cells, we have quantitated V beta 6+ T lymphocytes in a set of transgenic mice showing variant patterns of E expression in the thymus. We demonstrate that class II molecules must be expressed on epithelial cells of the cortex for positive selection to occur. Using a direct assay of unmanipulated thymocytes, we show that positive selection is manifest only as a rather late event in thymocyte differentiation, after the maturation of cortical double-positives into single-positives.

Publication types

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

MeSH terms

  • Animals
  • Antibodies, Monoclonal
  • Antigens, Differentiation, T-Lymphocyte / analysis
  • CD8 Antigens
  • Flow Cytometry
  • Histocompatibility Antigens Class II / genetics*
  • Immunoglobulin Variable Region / genetics
  • Lymph Nodes / immunology
  • Mice
  • Mice, Transgenic
  • T-Lymphocytes / classification
  • T-Lymphocytes / immunology*


  • Antibodies, Monoclonal
  • Antigens, Differentiation, T-Lymphocyte
  • CD8 Antigens
  • Histocompatibility Antigens Class II
  • Immunoglobulin Variable Region