title: Enhanced T-cell activation by immature dendritic cells loaded with HSP70-expressing heat-killed melanoma cells.
abstract: Vaccination protocols that utilize dendritic cells (DCs) to elicit therapeutic immunity against tumors are the subject of intense research. Given that the capacity of DCs to cross-present antigens is physiologically low, there is considerable interest to develop strategies that enhance that pathway. In order to best exploit the enhanced cross-presentation of antigens bound to heat shock protein 70 (HSP70), we analysed melanoma cell preparations for their HSP70 expression. Western blotting revealed strong upregulation of HSP70 after heat-killing in contrast to UV-B irradiation. When the uptake of heat-killed necrotic cells by DCs at various levels of maturation was assessed, 61 +/- 7% of immature DCs (iDCs) internalized fluorescence-labelled necrotic material. Apoptotic material from UV-B-irradiated cells was internalized by only 48 +/- 5% of iDCs. Maturation-inducing cytokines did not affect the uptake when added simultaneously with the tumor cell preparations. Loading DCs with heat-necrotic or apoptotic melanoma cells slightly reduced CD83 expression while leaving CD208 (DC-LAMP) expression unchanged. As determined by IFN-gamma-detecting enzyme-linked-immunospot assays, iDCs loaded with heat-killed melanoma cells activated autologous T cells most effectively when used without any further maturation, whereas DCs loaded with apoptotic material required maturation. In conclusion, HSP70-expressing melanoma cells could be generated by heat-killing. Loading iDCs with heat-killed melanoma cells resulted in a superior priming of autologous T cells in vitro.
authors.affiliation: Department of Dermatology and Venereology, Georg August University, Göttingen, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Knudsen
authors.forename: Anke
authors.initials: A
authors.lastname: Schardt
authors.forename: Timo
authors.initials: T
authors.lastname: Buhl
authors.forename: Lars
authors.initials: L
authors.lastname: Boeckmann
authors.forename: Michael P
authors.initials: MP
authors.lastname: Schön
authors.forename: Christine
authors.initials: C
authors.lastname: Neumann
authors.forename: Holger A
authors.initials: HA
authors.lastname: Haenssle
mesh_terms: D017209:Apoptosis; D045744:Cell Line, Tumor; D003713:Dendritic Cells / Q000276:immunology*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006358:Hot Temperature; D006801:Humans; D008213:Lymphocyte Activation; D008545:Melanoma / Q000276:immunology* / Q000378:metabolism; D010587:Phagocytosis; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D018840:HSP70 Heat-Shock Proteins