Target-dependent T-cell activation by coligation with a PSMA x CD3 diabody induces lysis of prostate cancer cells

J Immunother. Jul-Aug 2009;32(6):565-73. doi: 10.1097/CJI.0b013e3181a697eb.


Recently, we have described a bispecific PSMA x CD3 diabody with one binding site for the T-cell antigen receptor (TCR-CD3) and another for the Prostate Specific Membrane Antigen (PSMA). It effectively eliminates human prostate cancer cells by redirecting T-lymphocytes in vitro and in vivo. Here, we show that activation of the T-cells and killing of the tumor cells, only occurred when the T-cells were coincubated with PSMA-positive tumor cells and the PSMA x CD3 diabody. Both CD4+ and CD8+ human T-lymphocytes were activated. Surprisingly, they were equally potent in their cytotoxic activity, proliferation, and up-regulation of activation markers. Both, CD4+, and CD8+ T-cells mainly used the perforin-granzyme- based pathway and to a somewhat lesser extent the FasL pathway to lyse tumor cells. When Jurkat T-cells were stimulated with the diabody alone, the TCR-CD3 was not triggered. In contrast, when the diabody was clustered with a secondary antibody the TCR-CD3 was stimulated as detected by Ca(2+)-influx and Erk, IkappaB, and linker of activated T-cell phosphorylation. Clustering of the diabody could also be achieved by the dimeric PSMA antigen expressed on tumor cells. Thus, although the diabody binds to all T-cells, only those in contact with PSMA-expressing cancer cells are activated. In conclusion, the PSMA x CD3 diabody is suitable for a controlled polyclonal T-cell therapy of prostate cancer.

MeSH terms

  • Antibodies, Bispecific / immunology
  • Antibodies, Bispecific / therapeutic use*
  • CD3 Complex / immunology*
  • CD4-Positive T-Lymphocytes / immunology*
  • CD4-Positive T-Lymphocytes / transplantation
  • CD8-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / transplantation
  • Calcium / metabolism
  • Cell Line, Tumor
  • Cytokines / immunology
  • Fas Ligand Protein / immunology
  • Fas Ligand Protein / metabolism
  • Humans
  • Lymphocyte Activation*
  • Male
  • Perforin / immunology
  • Perforin / metabolism
  • Prostate-Specific Antigen / immunology*
  • Prostatic Neoplasms / immunology
  • Prostatic Neoplasms / therapy*
  • Up-Regulation


  • Antibodies, Bispecific
  • CD3 Complex
  • Cytokines
  • FASLG protein, human
  • Fas Ligand Protein
  • Perforin
  • Prostate-Specific Antigen
  • Calcium