Human dendritic cells genetically engineered to express cytosolically retained fragment of prostate-specific membrane antigen prime cytotoxic T-cell responses to multiple epitopes

Cancer Gene Ther. 2003 Dec;10(12):907-17. doi: 10.1038/sj.cgt.7700647.


The ability of two plasmid DNA vaccines to stimulate lymphocytes from normal human donors and to generate antigen-specific responses is demonstrated. The first vaccine (truncated; tPSMA) encodes for only the extracellular domain of prostate-specific membrane antigen (PSMA). The product, expressed following transfection with this vector, is retained in the cytosol and degraded by the proteasomes. For the "secreted" (sPMSA) vaccine, a signal peptide sequence is added to the expression cassette and the expressed protein is glycosylated and directed to the secretory pathway. Monocyte-derived dendritic cells (DCs) are transiently transfected with either sPSMA or tPSMA plasmids. The DCs are then used to activate autologous lymphocytes in an in vitro model of DNA vaccination. Lymphocytes are boosted following priming with transfected DCs or with peptide-pulsed monocytes. Their reactivity is tested against tumor cells or peptide-pulsed T2 target cells. Both tPSMA DCs and sPSMA DCs generate antigen-specific cytotoxic T-cell responses. The immune response is restricted toward one of the four PSMA-derived epitopes when priming and boosting is performed with sPSMA. In contrast, tPSMA-transfected DCs prime T cells toward several PSMA-derived epitopes. Subsequent repeated boosting with transfected DCs, however, restricts the immune response to a single epitope due to immunodominance.

Publication types

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

MeSH terms

  • Antigens, Surface / biosynthesis*
  • Antigens, Surface / genetics*
  • Dendritic Cells*
  • Genetic Engineering*
  • Glutamate Carboxypeptidase II / biosynthesis*
  • Glutamate Carboxypeptidase II / genetics*
  • Humans
  • Immunodominant Epitopes*
  • Immunotherapy / methods
  • Male
  • Peptide Fragments
  • Plasmids / genetics
  • Prostatic Neoplasms / genetics
  • Prostatic Neoplasms / immunology*
  • Prostatic Neoplasms / therapy*
  • T-Lymphocytes, Cytotoxic / immunology*
  • Transfection
  • Vaccines, DNA / genetics*
  • Vaccines, DNA / immunology*


  • Antigens, Surface
  • Immunodominant Epitopes
  • Peptide Fragments
  • Vaccines, DNA
  • FOLH1 protein, human
  • Glutamate Carboxypeptidase II