title: Flt-3 ligand as adjuvant for DNA vaccination augments immune responses but does not skew TH1/TH2 polarization.
abstract: Since transfection of dendritic cells (DC) plays a key role in DNA vaccination, in vivo expansion of DC might be a tool to increase vaccine efficacy. We asked whether Fms-like tyrosine kinase-3 ligand (Flt-3L), a growth factor for DC, can be used as an adjuvant for DNA vaccination. Beta-galactosidase (beta-gal) was used as a model antigen in C57BL/6 mice. Mice were immunized i.m. with DNA coding for beta-gal with or without additional injection of Flt-3L. In both cases, antigen-specific CD4+ and CD8+ T cells were detectable after vaccination. Compared with DNA alone, additional administration of Flt-3L led to a significant increase in the antigen-specific proliferative response. However, increased cytotoxicity by T cells was not observed. The cytokines secreted by splenocytes of immunized mice upon in vitro stimulation with antigen had a TH2 profile. Humoral responses against beta-gal preferentially consisted of IgG1 antibodies. Analysis of DC from Flt-3L-treated mice revealed an immature phenotype with low or absent expression levels of CD80, CD86 and CD40. We conclude that Flt-3L does not generally skew immune responses towards a TH1 type. More likely, factors determined by the antigen and/or the vaccination procedure itself are crucial for the resulting type of immune response. Flt-3L - under circumstances such as the one we have investigated - can also lead to suppression of TH1 T cell immunity, possibly by expansion of immature/unactivated DC.
authors.affiliation: Department of Hematology, Oncology and Tumorimmunology, Charité - University Medicine Berlin, Campus Berlin-Buch, Berlin, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Westermann
authors.forename: T
authors.initials: T
authors.lastname: Nguyen-Hoai
authors.forename: A
authors.initials: A
authors.lastname: Mollweide
authors.forename: G
authors.initials: G
authors.lastname: Richter
authors.forename: O
authors.initials: O
authors.lastname: Schmetzer
authors.forename: H-J
authors.initials: HJ
authors.lastname: Kim
authors.forename: Th
authors.initials: T
authors.lastname: Blankenstein
authors.forename: B
authors.initials: B
authors.lastname: Dörken
authors.forename: A
authors.initials: A
authors.lastname: Pezzutto
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000818:Animals; D000906:Antibodies / Q000097:blood; D002455:Cell Division; D003713:Dendritic Cells / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D005434:Flow Cytometry; D007074:Immunoglobulin G / Q000276:immunology; D007150:Immunohistochemistry; D007273:Injections, Intramuscular; D007371:Interferon-gamma / Q000097:blood; D008565:Membrane Proteins / Q000008:administration & dosage*; D051379:Mice; D008810:Mice, Inbred C57BL; D018417:Th1 Cells / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology*; D019444:Vaccines, DNA / Q000008:administration & dosage*; D001616:beta-Galactosidase / Q000235:genetics* / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D000906:Antibodies; D007074:Immunoglobulin G; D008565:Membrane Proteins; D019444:Vaccines, DNA; C084881:flt3 ligand protein; D007371:Interferon-gamma; D001616:beta-Galactosidase