TCR-Independent and Caspase-Independent Apoptosis of Murine Thymocytes by CD24 Cross-Linking

• Published in: The Journal of immunology (1950) Vol. 172; no. 2; pp. 795 - 802
• Main Authors: Jung, Kyeong Cheon, Park, Weon Seo, Kim, Hae Jung, Choi, Eun Young, Kook, Myeong-Cherl, Lee, Han-Woong, Bae, Youngmee
• Format: Journal Article
• Language: English
• Published: United States Am Assoc Immnol 15.01.2004
• Subjects: Animals; Antibodies, Monoclonal - metabolism; Antigens, CD - immunology; Antigens, CD - metabolism; Antigens, CD - physiology; Apoptosis - genetics; Apoptosis - immunology; Apoptosis Inducing Factor; Caspases - metabolism; Caspases - physiology; CD24 Antigen; Cell Line; Cell Line, Tumor; Cells, Cultured; Down-Regulation - immunology; Enzyme Activation; Flavoproteins - metabolism; Intracellular Membranes - immunology; Ligands; Membrane Glycoproteins; Membrane Potentials - immunology; Membrane Proteins - metabolism; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Inbred MRL lpr; Mice, Knockout; Mice, SCID; Mitochondria - immunology; Permeability; Reactive Oxygen Species - metabolism; Receptors, Antigen, T-Cell - physiology; T-Lymphocyte Subsets - cytology; T-Lymphocyte Subsets - enzymology; T-Lymphocyte Subsets - immunology; T-Lymphocyte Subsets - metabolism; Thymus Gland - cytology; Thymus Gland - enzymology; Thymus Gland - immunology; Thymus Gland - metabolism
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.172.2.795

CD24, also referred to as the heat-stable Ag, is a T cell differentiation Ag that is highly expressed on both CD4-CD8- double negative and CD4+CD8+ double positive thymocytes. Here, we report that CD24 ligation by a new anti-CD24 Ab, mT-20, induced the apoptosis of both double negative and double positive thymocytes, as well as the Scid.adh thymic lymphoma cell line, in the absence of TCR/CD3 engagement. CD24-mediated apoptosis of mouse thymocytes and its signaling pathway appeared not to be associated with p53, CD95, TNFR, or caspases. Furthermore, we found that cell death was blocked by the addition of scavengers of reactive oxygen species or by Bcl-2 overexpression, implying the role of CD24 signaling in the mitochondrial regulation. In this study, we suggest that CD24 ligation induced the apoptosis of immature thymocytes independently of both caspase and TCR.