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Defective TCR signaling events in glycosylphosphatidylinositol-deficient T cells derived from paroxysmal nocturnal hemoglobinuria patients.

  • Romagnoli P Institute of Biochemistry, BIL Biomedical Research Centre, University of Lausanne, 1066 Epalinges, Switzerland.
  • Bron C
  • 1999-08-28
Published in:
  • International immunology. - 1999
CD4-Positive T-Lymphocytes
CD8-Positive T-Lymphocytes
Calcium
Dose-Response Relationship, Immunologic
Enzyme Activation
Glycosylphosphatidylinositols
Hemoglobinuria, Paroxysmal
Humans
Lymphocyte Activation
Lymphocyte Specific Protein Tyrosine Kinase p56(lck)
Phosphorylation
Protein-Tyrosine Kinases
Receptors, Antigen, T-Cell
Receptors, Antigen, T-Cell, gamma-delta
Signal Transduction
English Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hemolytic disorder characterized by the presence of abnormal cells of various hematopoietic cell lineages deficient in surface expression of glycosylphosphatidylinositol (GPI)-anchored molecules. By analyzing T cells isolated from patients affected with PNH, it was found that ex vivo GPI-deficient CD4(+) and CD8(+) peripheral T cells display a more naive phenotype as compared to wild-type cells. In addition, in vitro proliferative responses to allogeneic antigen-presenting cells were shown to be reduced in mutant T cells. To investigate the molecular basis responsible for defective T cell activation in GPI-deficient T cells, T cell lines and T cell clones were generated from patients affected with PNH. When stimulated with anti-CD3epsilon mAb, mutant cells displayed a significantly decreased activation of protein tyrosine kinase p56(lck). The decreased kinase activity was accompanied by a delayed TCR capping and internalization. Interestingly, protein tyrosine phosphorylation is not only quantitatively but also qualitatively affected, with one substrate being more intensively phosphorylated in mutant than in wild-type cells. These observations suggest that a defective activation of p56(lck) contributes to the depressed immune responses observed in GPI-deficient T cells derived from PNH patients.
Language
  • English
Open access status
bronze
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Persistent URL
https://sonar.ch/global/documents/277799
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