title: A functional recombinant single-chain T cell receptor fragment capable of selectively targeting antigen-presenting cells.
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 alpha/beta T-cell receptor was cloned from such CTL which exhibited a moderately high affinity to the human p53(149-157) 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.
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Technion City, Room 333, Haifa 32000, Israel.
authors.forename: Malka
authors.initials: M
authors.lastname: Epel
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Ellenhorn
authors.forename: Don J
authors.initials: DJ
authors.lastname: Diamond
authors.forename: Yoram
authors.initials: Y
authors.lastname: Reiter
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000938:Antigen-Presenting Cells / Q000187:drug effects* / Q000276:immunology; D002460:Cell Line; D002461:Cell Line, Transformed; D016503:Drug Delivery Systems; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000737:chemistry; D051379:Mice; D008969:Molecular Sequence Data; D010455:Peptides / Q000276:immunology; D017510:Protein Folding; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000737:chemistry / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics*; D011994:Recombinant Proteins / Q000737:chemistry / Q000633:toxicity; D057127:Single-Chain Antibodies; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000276:immunology
chemical_list: D007135:Immunoglobulin Variable Region; D010455:Peptides; D016693:Receptors, Antigen, T-Cell, alpha-beta; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D057127:Single-Chain Antibodies; D016159:Tumor Suppressor Protein p53; C469384:p53 TCR scFv-P38 fusion protein, recombinant