Role of nitric oxide in heat shock protein induced apoptosis of gammadeltaT cells

Int J Cancer. 2006 Sep 15;119(6):1368-76. doi: 10.1002/ijc.21966.


Activation induced cell death (AICD) has been proposed to serve as a mechanism to limit T lymphocyte proliferation induced by antigenic stimulation. Heat shock proteins (hsp60 and hsp70) expressed on oral tumor cells serve as ligands for peripheral blood gammadeltaT lymphocytes. Tumor cell lysis by gammadeltaT lymphocytes is mediated via recognition of hsp expressed on tumor cells. In the present study, we report that upon stimulation with hsp, gammadeltaT lymphocytes isolated from oral cancer patients undergo AICD as confirmed by DNA ploidy, annexin V staining and confocal microscopy. In cocultures of gammadeltaT lymphocytes and tumor cells, addition of antihsp60 and antihsp70 MAb, but not anti-Fas MAb (ZB4), inhibited DNA fragmentation of gammadeltaT lymphocytes. Flow cytometric analysis revealed a down regulation of Fas expression on gammadeltaT lymphocytes upon incubation with hsp60 and hsp70. Increased expression of iNOS was observed in hsp-stimulated gammadeltaT lymphocytes. Addition of monomethyl L-arginine monoacetate, competitive inhibitor of NOS, inhibited nitric oxide (NO) production and apoptosis of gammadeltaT lymphocytes induced by hsp60 and hsp70. The NO-induced apoptosis of gammadeltaT lymphocytes involves activation of caspase-9 and loss of mitochondrial membrane potential. The present study explains a novel strategy adopted by tumor cells to evade immune recognition by gammadeltaT lymphocytes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis*
  • Blotting, Western
  • Carcinoma, Squamous Cell / immunology
  • Carcinoma, Squamous Cell / pathology*
  • Caspase 9
  • Caspases / metabolism
  • Chaperonin 60 / metabolism*
  • Down-Regulation
  • Enzyme Activation
  • Flow Cytometry
  • HSP70 Heat-Shock Proteins / metabolism*
  • Humans
  • Lymphocyte Activation
  • Membrane Potentials
  • Mitochondria / metabolism
  • Mouth Neoplasms / immunology
  • Mouth Neoplasms / pathology*
  • Nitric Oxide / physiology*
  • Nitric Oxide Synthase Type II / antagonists & inhibitors
  • Nitric Oxide Synthase Type II / metabolism
  • Receptors, Antigen, T-Cell, gamma-delta / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • T-Lymphocytes / pathology*
  • Tumor Cells, Cultured
  • fas Receptor / immunology
  • fas Receptor / metabolism


  • Chaperonin 60
  • HSP70 Heat-Shock Proteins
  • Receptors, Antigen, T-Cell, gamma-delta
  • fas Receptor
  • Nitric Oxide
  • Nitric Oxide Synthase Type II
  • CASP9 protein, human
  • Caspase 9
  • Caspases