title: In vivo depletion of CD4+CD25+ regulatory T cells enhances the antigen-specific primary and memory CTL response elicited by mature mRNA-electroporated dendritic cells.
abstract: We previously described mRNA electroporation as an efficient gene delivery method to introduce tumor-antigens (Ag) into murine immature dendritic cells (DC). Here, we further optimize the protocol and evaluate the capacity of mRNA-electroporated DC as a vaccine for immunotherapy. First, the early DC maturation kinetics and the effect of different lipopolysaccharide incubation periods on the phenotypic maturation profile of DC are determined. Next, we show that either immature or mature DC are equally well electroporated and express and present the transgene at a comparable level after electroporation. We point out that the mRNA electroporation results in a negative effect on the interleukin (IL)-12p70, IL-6, and tumor necrosis factor-alpha secretion after maturation. Nevertheless, mRNA-electroporated DC induce an effective cytotoxic T lymphocyte (CTL) response in vivo. Mature electroporated DC are significantly more potent in eliciting an Ag-specific CD8+ CTL response compared to their immature electroporated counterparts. In addition, a significant improvement in CTL response is obtained both in the primary and in the memory effector phases when CD4+CD25+ regulatory T cells (Treg) are depleted in vivo prior to immunization. These findings are further substantiated in tumor protection experiments and hold convincing evidence for the merit of Treg cell depletion prior to immunization with mRNA-electroporated DC.
authors.affiliation: Laboratory of Molecular and Cellular Therapy, Department of Physiology and Immunology, Medical School of Vrije Universiteit Brussel, Laarbeeklaan 103 E/3, 1090 Brussels, Belgium.
authors.forename: Sonja
authors.initials: S
authors.lastname: Van Meirvenne
authors.forename: Melissa
authors.initials: M
authors.lastname: Dullaers
authors.forename: Carlo
authors.initials: C
authors.lastname: Heirman
authors.forename: Lieven
authors.initials: L
authors.lastname: Straetman
authors.forename: Annelies
authors.initials: A
authors.lastname: Michiels
authors.forename: Kris
authors.initials: K
authors.lastname: Thielemans
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D017951:Antigen Presentation; D000951:Antigens, Neoplasm; D051927:CD24 Antigen; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology*; D018274:Electroporation; D005260:Female; D018014:Gene Transfer Techniques; D007167:Immunotherapy; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D009369:Neoplasms / Q000628:therapy; D012333:RNA, Messenger / Q000235:genetics*; D015375:Receptors, Interleukin-2; D013601:T-Lymphocytes / Q000276:immunology*; D014161:Transduction, Genetic; D019444:Vaccines, DNA
chemical_list: D000951:Antigens, Neoplasm; D051927:CD24 Antigen; D016207:Cytokines; D012333:RNA, Messenger; D015375:Receptors, Interleukin-2; D019444:Vaccines, DNA