Effects of desialyation on TCR-cross-linking and antigen sensitivity of CD8 positive T lymphocytes
Effekte von Neuraminidase auf TCR-cross-linking und Antigensensitivität von CD 8 positiven T Lymphozyten
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- The featured experiments focus on changes in T cell membrane glycosylation as a possible means of controlling TCR cross-linking. Taking the long known fact that activated T cells show decreased levels of surface sialic acid as a starting point, differences in ligand binding and cellular reaction upon in vitro stimulation were investigated in naïve, activated and enzymatically desialyated CD8+, 2C TCR transgenic mouse lymphocytes. To detect differences in ligand binding lymphocytes were incubated with various concentrations of fluorescentlyThe featured experiments focus on changes in T cell membrane glycosylation as a possible means of controlling TCR cross-linking. Taking the long known fact that activated T cells show decreased levels of surface sialic acid as a starting point, differences in ligand binding and cellular reaction upon in vitro stimulation were investigated in naïve, activated and enzymatically desialyated CD8+, 2C TCR transgenic mouse lymphocytes. To detect differences in ligand binding lymphocytes were incubated with various concentrations of fluorescently labeled, soluble MHC/Ig fusion proteins until equilibrium was reached. Without previous washing, cells were analyzed by flow cytometry, determined MCF values were normalized to the plateau and fit to a mathematical model of equilibrium binding of divalent ligands to monomorphic receptors (Perelson 1984). Parameters derived from the model fit of binding data show, that neuraminidase treatment of T cells was sufficient to mimic a partially activated phenotype, showing enhanced TCR cross-linking. Enhanced TCR cross-linking was found to be dependent on the presence of CD8, as neuraminidase treatment of DN cells lead to decreased cross-linking. To elucidate the physiological relevance of desialyation induced increases in TCR cross-linking early tyrosine phosphorylation events and proliferative response upon in vitro stimulation of T cells were investigated. Both were found enhanced in neuraminidase treated cells, as compared to native cells. In conclusion the featured experiments suggest a role of surface sialic acid in controlling TCR cross-linking on naïve and activated T cells.…
- Die vorliegenden Experimente zeigen einen Effekt von Neuraminidaseverdauung auf das Bindungsverhalten des T-Zell-Rezeptors der CD8 positiven T-Zelle gegenüber ihrem MHC I Liganden. In vitro Bindungsexperimente, Phosphorylierungs- und Proliferationsassays zeigen, dass Entfernung von Sialylsäure auf T-Lymphozyten einen Phänotyp erzeugt, der dem einer aktivierten T Zelle gleicht. Ein mögliches Schlüsselmolekül für den beobachteten Neuraminidase-Effekt stellt "CD8" dar.
Autor(en): | Lars Eichler |
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URN: | urn:nbn:de:bvb:20-opus-19391 |
Dokumentart: | Dissertation |
Titelverleihende Fakultät: | Universität Würzburg, Medizinische Fakultät |
Institute der Universität: | Medizinische Fakultät / Institut für Virologie und Immunbiologie |
Datum der Abschlussprüfung: | 11.08.2006 |
Sprache der Veröffentlichung: | Englisch |
Erscheinungsjahr: | 2005 |
Allgemeine fachliche Zuordnung (DDC-Klassifikation): | 6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit |
Freie Schlagwort(e): | CD 8; Sialylsäure; T Lymphozyt; TCR TCR; cross-linking; sialic acid |
Datum der Freischaltung: | 02.10.2006 |
Betreuer: | Prof. Dr. rer. nat. Thomas Hünig |