CD4+CD8+ thymocytes are susceptible to DNA fragmentation induced by phorbol ester, calcium ionophore and anti-CD3 antibody

• Published in: European journal of immunology Vol. 20; no. 4; p. 779
• Main Authors: Tadakuma, T, Kizaki, H, Odaka, C, Kubota, R, Ishimura, Y, Yagita, H, Okumura, K
• Format: Journal Article
• Language: English
• Published: Germany 01.04.1990
• Subjects: Animals; Antibodies, Monoclonal - immunology; Antigens, Differentiation, T-Lymphocyte - immunology; Antigens, Differentiation, T-Lymphocyte - physiology; Calcimycin - pharmacology; CD3 Complex; CD4-Positive T-Lymphocytes - immunology; CD4-Positive T-Lymphocytes - metabolism; DNA - metabolism; Mice; Mice, Inbred C57BL; Receptors, Antigen, T-Cell - immunology; Receptors, Antigen, T-Cell - physiology; T-Lymphocytes, Regulatory - immunology; T-Lymphocytes, Regulatory - metabolism; Tetradecanoylphorbol Acetate - pharmacology
• ISSN: 0014-2980
• DOI: 10.1002/eji.1830200411

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.