Differential surface expression and possible function of 9-O- and 7-O-acetylated GD3 (CD60 b and c) during activation and apoptosis of human tonsillar B and T lymphocytes |
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Authors: | Michael Erdmann Dirk Wipfler Anette Merling Yi Cao Christine Claus Bernhard Kniep Haneen Sadick Wolfgang Bergler Reinhard Vlasak Reinhard Schwartz-Albiez |
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Affiliation: | (1) Tumor Immunology Program, German Cancer Research Center, D-69120 Heidelberg, Germany;(2) Department of Cardiothoracic and Vascular Surgery, University Hospital Mainz, Mainz, Germany;(3) Institute of Immunology, Technical University of Dresden, D-01307 Dresden, Germany;(4) Department of Oto-Rhino-Laryngology, University of Mannheim, Mannheim, Germany;(5) St. Joseph Hospital, D-28209 Bremen, Germany;(6) Applied Biotechnology, Department of Cell Biology, University Salzburg, A-5020 Salzburg, Austria;(7) German Cancer Research Center, D010, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany |
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Abstract: | The disialoganglioside GD3 (CD60 a) and its O-acetylated variants have previously been described as surface molecules of human T lymphocytes of the peripheral blood system. Here we report the expression of the 9-O-, and 7-O-acetylated disialoglycans of GD3 (CD60 b and CD60 c respectively) on human tonsillar lymphocytes. CD60 b and c are surface-expressed on activated germinal centre B cells and colocalize in raft-like structures on the cell surface together with the cytoplasmic tyrosine kinase Lyn and Syk. Addition of CD60 b and c mAb together with anti-IgM/IL-4 to in vitro cultivated tonsillar B cells resulted in a costimulatory effect. During spontaneous and staurosporine-induced apoptosis a distinct population of activated annexin V+/CD60 b+/CD60 c- B cells was observed. CD60 b and c are also found on cells of the extrafollicular T cell area. On tonsillar T cells, CD60 b mAb had a costimulatory effect together with PHA while CD60 c mAb alone was sufficient to induce proliferation. In further contrast to B cells, during apoptosis a distinct CD60 b+ T cell subpopulation was not observed. Together, surface-expressed CD60 b and c are differently expressed on tonsillar B and T cells and may be involved in the regulation of activation and apoptosis of lymphocytes in secondary lymphatic tissue. |
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Keywords: | Ganglioside Germinal center Lipid rafts O-acetylated sialic acid Signal transduction |
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