title: IL-12 plasmid-enhanced DNA vaccination against carcinoembryonic antigen (CEA) studied in immune-gene knockout mice.
abstract: Intramuscular (i.m.) injection of a plasmid encoding human carcinoembryonic antigen (CEA) elicited immunity against transplanted syngeneic (C57BL/6) CEA-positive Lewis lung carcinoma (CEA/LLC) cells, but tumors still appeared in all mice. In wild-type mice, coinjection of an IL-12 plasmid markedly enhanced anti-CEA humoral, T-helper-1 and cytotoxic T lymphocyte (CTL) responses, and resistance to a CEA/LLC tumor challenge such that 80% of mice remained tumor free. Injection of the IL- 12 plasmid alone was not protective. To analyze immune requirements, we immunized gene knockout (KO) mice of C57BL/6 background, deficient in either CD3, CD4, CD8, interferon gamma (IFNgamma), perforin or Fas ligand (FasL). Only CD3+ mice expressing both CD4 and CD8, which appear equally important, as well as IFNgamma and perforin, could fully resist a tumor challenge. IL-12 stimulated CTL activity, which was strictly CD3/CD8/perforin-dependent. FasL-KO mice had normal CTL activity and tumor resistance, indicating that only the perforin lytic pathway was involved. CD4-KO and IFNgamma-KO mice still generated CTLs. CEA-stimulated IFNgamma production occurred in both CD4- or CD8-KO mice and in both cases was augmented by IL-12. In IFNgamma-KO mice, IL-12 still enhanced anti-CEA antibody production but only moderately restored impaired DTH and tumor resistance. We conclude that the immune requirements for tumor rejection are stringent, involving multiple mechanisms which are all enhanced by IL-12.
authors.affiliation: Department of Pathology, McGill University, Montreal, Quebec, Canada.
authors.forename: K
authors.initials: K
authors.lastname: Song
authors.forename: Y
authors.initials: Y
authors.lastname: Chang
authors.forename: G J
authors.initials: GJ
authors.lastname: Prud'homme
mesh_terms: D000818:Animals; D000917:Antibody Formation; D017252:CD3 Complex / Q000235:genetics; D015704:CD4 Antigens / Q000235:genetics; D016827:CD8 Antigens / Q000235:genetics; D002272:Carcinoembryonic Antigen / Q000235:genetics* / Q000276:immunology; D053222:Fas Ligand Protein; D005260:Female; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D007273:Injections, Intramuscular; D007371:Interferon-gamma / Q000235:genetics; D018664:Interleukin-12 / Q000235:genetics*; D008562:Membrane Glycoproteins / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000276:immunology / Q000628:therapy*; D054353:Perforin; D010957:Plasmids / Q000008:administration & dosage; D052899:Pore Forming Cytotoxic Proteins; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology; D013997:Time Factors; D014407:Tumor Cells, Cultured; D019444:Vaccines, DNA / Q000008:administration & dosage*
chemical_list: D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens; D002272:Carcinoembryonic Antigen; C505661:FASLG protein, human; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D019444:Vaccines, DNA; D054353:Perforin; D018664:Interleukin-12; D007371:Interferon-gamma