title: Selective targeting of melanoma and APCs using a recombinant antibody with TCR-like specificity directed toward a melanoma differentiation antigen.
abstract: Tumor-associated, MHC-restricted peptides, recognized by tumor-specific CD8(+) lymphocytes, are desirable targets for novel approaches in immunotherapy because of their highly restricted fine specificity. Abs that recognize these tumor-associated MHC-peptide complexes, with the same specificity as TCR, would therefore be valuable reagents for studying Ag presentation by tumor cells, for visualizing MHC-peptide complexes on cells, and eventually for developing new targeting agents for cancer immunotherapy. To generate molecules with such a unique, fine specificity, we immunized HLA-A2 transgenic mice with a single-chain HLA-A2, complexed with a common antigenic T cell HLA-A2-restricted epitope derived from the melanoma differentiation Ag gp100. Using a phage display approach, we isolated a recombinant scFv Ab that exhibits a characteristic TCR-like binding specificity, yet, unlike TCRs, it did so with a high affinity in the nanomolar range. The TCR-like Ab can recognize the native MHC-peptide complex expressed on the surface of APCs, and on peptide-pulsed or native melanoma cells. Moreover, when fused to a very potent cytotoxic effector molecule in the form of a truncated bacterial toxin, it was able to specifically kill APCs in a peptide-dependent manner. These results demonstrate the utility of high affinity TRC-like scFv recombinant Abs directed toward human cancer T cell epitopes. Such TCR-like Abs may prove to be very useful for monitoring and visualizing the expression of specific MHC-peptide complexes on the surface of tumor cells, APCs, and lymphoid tissues, as well as for developing a new family of targeting agents for immunotherapy.
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Technion City, Room 333, Haifa 32000, Israel.
authors.forename: Galit
authors.initials: G
authors.lastname: Denkberg
authors.forename: Avital
authors.initials: A
authors.lastname: Lev
authors.forename: Lea
authors.initials: L
authors.lastname: Eisenbach
authors.forename: Itai
authors.initials: I
authors.lastname: Benhar
authors.forename: Yoram
authors.initials: Y
authors.lastname: Reiter
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000235:genetics; D000938:Antigen-Presenting Cells / Q000276:immunology* / Q000378:metabolism*; D001435:Bacteriophages / Q000235:genetics; D001666:Binding Sites, Antibody / Q000235:genetics; D003602:Cytotoxicity, Immunologic / Q000235:genetics; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D015789:HLA-A2 Antigen / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics; D007424:Intracellular Fluid / Q000276:immunology / Q000378:metabolism; D046911:Macromolecular Substances; D008546:Melanoma, Experimental / Q000235:genetics / Q000276:immunology* / Q000378:metabolism / Q000628:therapy*; D008562:Membrane Glycoproteins / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D009363:Neoplasm Proteins / Q000276:immunology* / Q000378:metabolism; D019151:Peptide Library; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism / Q000494:pharmacology*; D012995:Solubility; D014407:Tumor Cells, Cultured; D058951:gp100 Melanoma Antigen
chemical_list: D018984:Epitopes, T-Lymphocyte; D015789:HLA-A2 Antigen; D007135:Immunoglobulin Variable Region; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; C548637:PMEL protein, human; D019151:Peptide Library; C548642:Pmel protein, mouse; D011948:Receptors, Antigen, T-Cell; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D058951:gp100 Melanoma Antigen