title: Induction by DNA immunization of a protective antitumor cytotoxic T lymphocyte response against a minimal-epitope-expressing tumor.
abstract: In order to examine the use of DNA immunization to block tumor growth, we have developed a model system in which a defined 9-amino-acid epitope from the nucleoprotein of influenza virus is used as a surrogate tumor-associated antigen. A mastocytoma cell line of DBA/2 origin (P815) was transfected with a plasmid encoding the minimal H-2Kd-restricted NP(147-155) cytotoxic T lymphocyte (CTL) epitope, pCMV/NPep, to generate the cell line designated P815-NPep. Mice primed and boosted once with a plasmid encoding the full-length NP gene, pCMV/NP, but not with the minigene pCMV/NPep, developed a strong NP(147-155)-specific CTL response within 2 weeks after the boost. When challenged with 10(4) P815-NPep cells, pCMV/NP-immunized DBA/2 mice were protected from tumor challenge, whereas control mice immunized with the vector backbone rapidly developed lethal tumor. Importantly, the P815-NPep-immune mice were also protected from a subsequent challenge with the untransfected parental tumor P815. By depleting the NP-immune mice of either CD4+ or CD8+ T cells and then challenging with 10(4) P815-NPep tumor cells, it was determined that the CD8-depleted mice rapidly developed tumors, whereas the CD4-depleted or non-treated mice were protected. These data clearly indicate that intramuscular (i.m.) plasmid DNA immunization can be used to mobilize an effective CD8+ CTL-mediated antitumor response.
authors.affiliation: Department of Immunology, University of Toronto, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Iwasaki
authors.forename: B H
authors.initials: BH
authors.lastname: Barber
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D019496:Cancer Vaccines / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D005260:Female; D006183:H-2 Antigens / Q000235:genetics / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology*; D012515:Mast-Cell Sarcoma / Q000235:genetics / Q000276:immunology* / Q000628:therapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D008811:Mice, Inbred DBA; D019590:Nucleocapsid Proteins; D009698:Nucleoproteins / Q000235:genetics / Q000276:immunology; D010957:Plasmids; D016601:RNA-Binding Proteins; D051381:Rats; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014162:Transfection; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*; D014758:Viral Core Proteins / Q000235:genetics / Q000276:immunology
chemical_list: D019496:Cancer Vaccines; D018984:Epitopes, T-Lymphocyte; D006183:H-2 Antigens; C024755:H-2K(K) antigen; D015395:Histocompatibility Antigens Class I; C048842:NP protein, Influenza A virus; D019590:Nucleocapsid Proteins; D009698:Nucleoproteins; D016601:RNA-Binding Proteins; D019444:Vaccines, DNA; D014758:Viral Core Proteins