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Fas ligand-positive membranous vesicles isolated from sera of patients with oral cancer induce apoptosis of activated T lymphocytes

Clin Cancer Res. 2005 Feb 1;11(3):1010-20.

Abstract

Objective: In patients with oral squamous cell carcinoma, a high proportion of T cells in the tumor undergo apoptosis, which correlates with Fas ligand (FasL) expression on tumor cells. The present study was done to identify mechanisms responsible for apoptosis of T cells seen in the peripheral circulation of these patients.

Methods: Sera of 27 patients, normal donor sera, and supernatants of cultured normal or tumor cells were fractionated by size exclusion chromatography and ultracentrifugation to isolate microvesicles. The presence of microvesicle-associated FasL was studied by Western blots, blocking with anti-Fas reagents, and immunoelectron microscopy. Biological activities of microvesicles were tested including the ability to induce apoptosis of Jurkat and T-cell blasts. Semiquantitative analysis of FasL in microvesicles was correlated with caspase-3 activity, DNA fragmentation, cytochrome c release, loss of mitochondrial membrane potential, and TCR-zeta chain expression in lymphocytes.

Results: FasL-positive (FasL+) microvesicles were detected in sera of 21 of 27 patients. Microvesicles contained 42 kDa FasL. These microvesicles induced caspase-3 cleavage, cytochrome c release, loss of mitochondrial membrane potential, and reduced TCR-zeta chain expression in target lymphocytes. Biological activity of the FasL+ microvesicles was partially blocked by ZB4 anti-Fas monoclonal antibody. Microvesicle-associated FasL levels correlated with the patients' tumor burden and nodal involvement.

Conclusion: Sera of patients with active oral squamous cell carcinoma contain FasL+ microvesicles, which induce the receptor and mitochondrial apoptotic pathways in Jurkat and activated T cells.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Monoclonal / immunology
  • Apoptosis*
  • Blotting, Western
  • Carcinoma, Squamous Cell / blood*
  • Carcinoma, Squamous Cell / immunology
  • Carcinoma, Squamous Cell / pathology
  • Caspase 3
  • Caspases / metabolism
  • Cell Line, Tumor
  • Cytochromes c / metabolism
  • Cytoplasmic Vesicles / metabolism*
  • Cytoplasmic Vesicles / ultrastructure
  • Down-Regulation
  • Fas Ligand Protein
  • Female
  • Flow Cytometry
  • Humans
  • Jurkat Cells
  • Male
  • Membrane Glycoproteins / blood
  • Membrane Glycoproteins / immunology
  • Membrane Glycoproteins / metabolism*
  • Membrane Proteins / metabolism
  • Microscopy, Electron
  • Middle Aged
  • Mitochondria / metabolism
  • Mitochondria / ultrastructure
  • Mouth Neoplasms / blood*
  • Mouth Neoplasms / immunology
  • Mouth Neoplasms / pathology
  • Receptors, Antigen, T-Cell / metabolism
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / pathology
  • fas Receptor / immunology
  • fas Receptor / metabolism

Substances

  • Antibodies, Monoclonal
  • FASLG protein, human
  • Fas Ligand Protein
  • Membrane Glycoproteins
  • Membrane Proteins
  • Receptors, Antigen, T-Cell
  • antigen T cell receptor, zeta chain
  • fas Receptor
  • Cytochromes c
  • CASP3 protein, human
  • Caspase 3
  • Caspases