Characterization of CD4+CD8+ thymocytes observed in SCID-bg mice

Immunol Cell Biol. 1997 Oct;75(5):472-7. doi: 10.1038/icb.1997.73.


Previously, we reported that a strain of severe combined immunodeficient (SCID) mice, namely SCID-bg, spontaneously develop CD4+CD8+ double positive (DP) thymocytes despite their scid mutation. In the present study, we intend to further characterize the DP thymocyte population in SCID-bg mice with Southern hybridization and flow cytometry. Southern hybridization analyses of sorted DP thymocytes in SCID-bg mice showed rearrangement of T cell receptor (TCR) beta and TCR gamma gene segments, although the expression of TCR beta and gamma delta TCR molecules was absent. The phenotype of the DP thymocytes in SCID-bg mice was CD44- heat-stable antigen (HSA)+CD25-, and they did not express CD69. Interestingly, the expression of thymus leukaemia (TL) antigen was observed in the DP thymocytes of SCID-bg mice but not in their CD4-CD8- double negative (DN) fraction. Fas expression was higher and bcl-2 expression was down-regulated in the DP thymocytes as compared to the DN thymocytes in SCID-bg mice, suggesting that they are not immortalized cells having escaped from apoptosis. Taken together, these results show that the phenotype of the DP thymocytes in SCID-bg mice is similar to that of the earliest phase of the DP thymocytes in normal mice, although the expression of the molecules in the pre-TCR complex is absent.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Southern
  • CD4 Antigens / analysis*
  • CD8 Antigens / analysis*
  • Flow Cytometry
  • Gene Rearrangement, T-Lymphocyte
  • Genes, T-Cell Receptor beta
  • Genes, T-Cell Receptor gamma
  • Mice
  • Mice, Inbred BALB C
  • Mice, SCID
  • Phenotype
  • Proto-Oncogene Proteins c-bcl-2 / analysis
  • Receptors, Antigen, T-Cell / analysis*
  • Receptors, Interleukin-2 / analysis
  • T-Lymphocyte Subsets
  • T-Lymphocytes / immunology*


  • CD4 Antigens
  • CD8 Antigens
  • Proto-Oncogene Proteins c-bcl-2
  • Receptors, Antigen, T-Cell
  • Receptors, Interleukin-2