title: Co-expression of Flt-3 ligand gene ablates tumor immunity elicited by HER-2/neu DNA vaccine in transgenic mice.
abstract: Fms-like tyrosine-kinase 3 ligand (Flt-3L), is a powerful hematopoyetic growth factor, known to modulate the immune response against delivered antigens by acting either as an adjuvant or tolerogenic stimulus. In this study we evaluated the use of murine Flt-3 ligand plasmid (pFl) in combination with a DNA vaccine encoding rat-p185 oncoprotein extra cellular domain (pECD) in the prevention of mammary carcinogenesis in rat-neu HER-2 mutated (neuT) transgenic mice. We demonstrate that intramuscular (i.m.) co-immunization of pFl inhibits the production of anti-HER-2 antibody elicited by pECD vaccine, resulting in the development of spontaneous carcinomas in all co-immunized mice. The inhibitory effect on antibody production by mFlt3 gene appeared to be: dose-dependent, linked to the injection site and timing, and transient in nature. Additionally, we show that co-administration of pFI and pECD plasmids was unable to trigger cytotoxic T-cell immune response in neuT mice. On the other hand, we found that the combination of pFl with pECD had no impact on the ability of pECD to reject HER-2+ transplantable tumors in parental mice. In summary our results demonstrate that, depending on tumor model, co-administration of pFl gene can produce untoward effects to immune response, and thus its application as a vaccine adjuvant should be carefully evaluated.
authors.affiliation: Laboratory of Translational Biology, Department of Biology MCA, via Gentile da Varano III, University of Camerino (MC), Italy. franco.venanzi@unicam.it
authors.forename: F M
authors.initials: FM
authors.lastname: Venanzi
authors.forename: A
authors.initials: A
authors.lastname: Barucca
authors.forename: K
authors.initials: K
authors.lastname: Havas
authors.forename: M
authors.initials: M
authors.lastname: Capitani
authors.forename: M
authors.initials: M
authors.lastname: Provinciali
authors.forename: S
authors.initials: S
authors.lastname: Scotti
authors.forename: A
authors.initials: A
authors.lastname: Concetti
mesh_terms: D000818:Animals; D000912:Antibodies, Neoplasm / Q000097:blood; D019496:Cancer Vaccines / Q000235:genetics / Q000276:immunology*; D045744:Cell Line, Tumor; D005260:Female; D008325:Mammary Neoplasms, Experimental / Q000276:immunology / Q000517:prevention & control*; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008822:Mice, Transgenic; D010957:Plasmids / Q000276:immunology; D051381:Rats; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology; D019444:Vaccines, DNA / Q000276:immunology*
chemical_list: D000912:Antibodies, Neoplasm; D019496:Cancer Vaccines; D008565:Membrane Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases; D019444:Vaccines, DNA; C084881:flt3 ligand protein