CD4+CD8+ thymocytes are susceptible to DNA fragmentation induced by phorbol ester, calcium ionophore and anti-CD3 antibody.
Stimulation of murine thymocytes with phorbol ester or calcium ionophore for 18-24 h resulted in 70%-80% fragmentation of DNA into 180-200-bp multiples, followed by cell death. Experiments with fractionated subpopulations by panning or flow cytometry revealed that DNA fragmentation was selectively observed in CD4+CD8+ cells and in a portion of CD4-CD8+ cells. To investigate whether DNA cleavage is also inducible via antigen-specific receptors, thymocytes were incubated in wells precoated with anti-CD3 antibody. An approximately 20% increase of DNA fragmentation was constantly observed when unseparated thymocytes were stimulated with anti-CD3 antibody. In this anti-CD3-induced DNA degradation, CD4+CD8+ cells are probably the target cells, since (a) fetal thymocytes at day 18 of gestation were found vulnerable to anti-CD3-induced DNA cleavage and (b) flow cytometry analysis of viable cells recovered after cultivation in the anti-CD3-coated wells revealed that CD4+CD8+ cells were preferentially decreased. Further experiments with purified CD4+CD8+ cells, however, could not define a clear-cut increase of DNA fragmentation when isolated CD4+CD8+ cells were stimulated with anti-CD3 antibody. Addition of interleukin (IL) 1, IL 2, IL 3, IL 4 or interferon-gamma to the CD4+CD8+ cell cultures failed to yield a DNA cleavage similar to that of unseparated thymocytes.
Tadakuma
T
T
Department of Microbiology, Keio University School of Medicine, Tokyo, Japan.
Kizaki
H
H
Odaka
C
C
Kubota
R
R
Ishimura
Y
Y
Yagita
H
H
Okumura
K
K
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology* / Q000502:physiology; D017252:CD3 Complex; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology*; D004247:DNA / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D011948:Receptors, Antigen, T-Cell / Q000276:immunology* / Q000502:physiology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D011948:Receptors, Antigen, T-Cell; D000001:Calcimycin; D004247:DNA; D013755:Tetradecanoylphorbol Acetate