Vesicles released by activated T cells induce both Fas-mediated RIP-dependent apoptotic and Fas-independent nonapoptotic cell deaths

J Immunol. 2012 Sep 15;189(6):2815-23. doi: 10.4049/jimmunol.1102827. Epub 2012 Aug 13.

Abstract

Activated T cells secrete Fas ligand (FasL)-containing vesicles (secreted vesicles) that induce death of target cells. We provide evidence that secreted vesicles from culture supernatants (Csup) of various origins are able to generate both Fas-dependent apoptotic and Fas-independent, nonapoptotic cell death. In the absence of Fas, the nonapoptotic, Fas-independent pathway could still induce cell death. In contrast to RIP-independent classical Fas-induced cell death triggered by cross-linked or membrane-bound FasL, CSup-derived stimuli-induced apoptosis exhibited unique molecular and enzymatic characteristics. It could be partially inhibited by blocking cathepsin D enzyme activity and required the presence of RIP. Whereas stimulation with CSup, derived from both FasL-overexpressing Jurkat cells and PBMC, could induce cell death, the requirements for Fas-associated death domain protein and caspase-9 were different between the two systems. Our study highlights an important distinction between cell contact-mediated and secreted vesicle-generated activation-induced cell death and also demonstrates that the type of the secreted vesicles can also modify the cell death route. We propose that besides cell-to-cell interaction-mediated Fas triggering, stimuli induced by secreted vesicles can mediate important additional cell death signals regulating activation-induced cell death under physiological conditions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / immunology*
  • Cell Communication / immunology
  • Cell Death / immunology
  • Cell Transformation, Neoplastic / immunology
  • Coculture Techniques
  • Culture Media, Conditioned
  • Cytidine Deaminase / physiology
  • Cytoplasmic Vesicles / enzymology
  • Cytoplasmic Vesicles / immunology*
  • Cytoplasmic Vesicles / metabolism*
  • Cytotoxicity Tests, Immunologic
  • Humans
  • Jurkat Cells
  • Lymphocyte Activation / immunology*
  • Melanoma, Experimental / immunology
  • Melanoma, Experimental / metabolism
  • Melanoma, Experimental / pathology
  • Receptor-Interacting Protein Serine-Threonine Kinases / physiology*
  • T-Lymphocyte Subsets / enzymology
  • T-Lymphocyte Subsets / immunology*
  • T-Lymphocyte Subsets / metabolism*
  • fas Receptor / physiology*

Substances

  • Culture Media, Conditioned
  • FAS protein, human
  • fas Receptor
  • Receptor-Interacting Protein Serine-Threonine Kinases
  • AICDA (activation-induced cytidine deaminase)
  • Cytidine Deaminase