Characterization of CD4+CD8+ thymocytes observed in SCID-bg mice.
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.
Shibata
S
S
Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan. shibata@nih.go.jp
Asano
T
T
Noguchi
A
A
Kimura
H
H
Hashimoto
N
N
Hayakawa
J
J
Ogura
A
A
Doi
K
K
D000818:Animals; D015139:Blotting, Southern; D015704:CD4 Antigens / Q000032:analysis*; D016827:CD8 Antigens / Q000032:analysis*; D005434:Flow Cytometry; D015329:Gene Rearrangement, T-Lymphocyte; D019674:Genes, T-Cell Receptor beta; D019675:Genes, T-Cell Receptor gamma; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D010641:Phenotype; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D011948:Receptors, Antigen, T-Cell / Q000032:analysis*; D015375:Receptors, Interleukin-2 / Q000032:analysis; D016176:T-Lymphocyte Subsets; D013601:T-Lymphocytes / Q000276:immunology*
D015704:CD4 Antigens; D016827:CD8 Antigens; D019253:Proto-Oncogene Proteins c-bcl-2; D011948:Receptors, Antigen, T-Cell; D015375:Receptors, Interleukin-2