Original Article

Cancer Immunology, Immunotherapy

, Volume 51, Issue 10, pp 565-573

First online:

A functional recombinant single-chain T cell receptor fragment capable of selectively targeting antigen-presenting cells

  • Malka EpelAffiliated withFaculty of Biology, Technion-Israel Institute of Technology, Technion City, Room 333, Haifa 32000, Israel
  • , Joshua D. EllenhornAffiliated withDivision of General and Oncologic Surgery, Beckman Research Institute of the City of Hope and City of Hope National Medical Center, Duarte, California 91010, USA
  • , Don J. DiamondAffiliated withLaboratory of Vaccine Research, Beckman Research Institute of the City of Hope and City of Hope National Medical Center, Duarte, California 91010, USA
  • , Yoram ReiterAffiliated withFaculty of Biology, Technion-Israel Institute of Technology, Technion City, Room 333, Haifa 32000, Israel

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Abstract.

Specificity in the immune system is dictated and regulated by specific recognition of peptide/major histocompatibility complexes (MHC) by the T cell receptor (TCR). Such peptide/MHC complexes are a desirable target for novel approaches in immunotherapy because of their highly restricted fine specificity. Recently a potent anti-human p53 CD8+ cytotoxic T lymphocyte (CTL) response has been developed in HLA-A2 transgenic mice after immunization with peptides corresponding to HLA-A2 motifs from human p53. An α/β T-cell receptor was cloned from such CTL which exhibited a moderately high affinity to the human p53149–157 peptide. In this report, we investigated the possibility of using a recombinant tumor-specific TCR for antigen-specific elimination of cells that express the specific MHC-peptide complex. To this end, we constructed a functional single-chain Fv fragment from the cloned TCR and fused it to a very potent cytotoxic molecule, a truncated form of Pseudomonas exotoxin A (PE38). The p53 TCR scFv-P38 fusion protein was generated by in vitro refolding from bacterially-expressed inclusion bodies, and was found to be functional by its ability to bind antigen-presenting cells (APC) which express the specific p53-derived peptide. Moreover, we have shown that the p53-specific TCR scFv-PE38 molecule specifically kills APC in a peptide-dependent manner. These results represent the first time that a TCR-derived recombinant single-chain Fv fragment has been used as a targeting moiety to deliver a cytotoxic effector molecule to cells and has been able to mediate the efficient killing of the particular cell population that expresses the specific MHC/peptide complex. Similarly to antibody-based targeting approaches, TCR with tumor cell specificity represent attractive candidates for generating new, very specific targeting moieties for various modes of cancer immunotherapy.

Cancer-specific targeting Single-chain Fv T-cell receptor