Therapy of established tumour with a hybrid cellular vaccine generated by using granulocyte–macrophage colony‐stimulating factor genetically modified dendritic cells

Abstract

SUMMARYDendritic cells (DCs) are the most powerful of all antigen-presenting cells and play a critical role in the induction of primary immune responses. DC-based vaccination represents a potentially powerful strategy for cancer immunotherapy. In this study, a new approach for a DC-based melanoma vaccine was described. Splenic DCs from C57BL/6 mice were fused with B16 melanoma cells, and the resultant B16/DC hybrid cells expressed major histocompatibility complex (MHC ) molecules -B7 as well as the B16 tumour marker M562 -which were enriched by Ia-mediated positive selection with a MiniMACS column. The fusion rates were 12·7-26·8%. To generate hybrid tumour vaccines with potentially greater potent therapeutic efficacy, we genetically engineered DCs with granulocyte-macrophage colony-stimulating factor (GM-CSF ) prior to cell fusion. Recombinant adenovirus vector was used to mediate gene transfer into DCs with high efficiency and DCs expressed GM-CSF at 96-138 ng/105 cells/ml 24 hr after GM-CSF gene transfer. GM-CSF gene-modified DCs (DC.GM ) exhibited higher expression of B7 and co-stimulatory capacity in mixed lymphocyte reaction (MLR). Fusion of DC.GM with B16 cells generated B16/DC.GM hybrid cells secreting GM-CSF at 59-63 ng/105 cells/ml. Immunization of C57BL/6 mice with the B16/DC hybrid vaccine elicited a specific cytotoxic T-lymphocyte (CTL) response and protected the immunized mice from B16 tumour challenge, reduced pulmonary metastases and extended the survival of B16 tumour-bearing mice. The B16/DC.GM hybrid vaccine was able to induce a CTL response and protective immunity more potently and tended to be therapeutically more efficacious than the B16/DC vaccine. In vivo depletion of T-cell subsets demonstrated that both CD8+ and CD4+ T cells were essential for the therapeutic effects of B16/DC and B16/DC.GM hybrid vaccines. Additionally, other non-specific effector cells may also contribute to tumour rejection induced by the B16/DC.GM hybrid vaccine. These data indicate that a DC-based hybrid tumour vaccine may be an attractive strategy for cancer immunotherapy, and that GM-CSF gene-modified DCs may lead to the generation of hybrid vaccines with potentially increased therapeutic efficacy.

Antitumor immunopreventive and immunotherapeutic effect in mice induced by hybrid vaccine of dendritic cells and hepatocarcinomain vivo

“…Hybrid vaccine could express some DC characteristics such as membrane molecule MHC-I, II molecule and costimulator, secrete some cell factors which can stimulate the T cell expansion, capture and present endogenous tumor associated antigens derived form parents H 22 cells, so it can efficiently stimulate the immune response [21][22][23][24][25] . There were similar results in other research reports on hybrid vaccines of DC with MC38, NS1, B16 melanoma, RMA-s lymphpma and renal carcinoma [26][27][28][29][30][31][32][33][34][35] . Mice immunized by hybrid vaccine could induce the tumor specific memory T cells, which could quickly be activated and expanded when they contact with tumor antigen again.…”

Macrophage-derived chemokine gene transfer results in tumor regression in murine lung carcinoma model through efficient induction of antitumor immunity

“…[54][55][56] In brief, erythrocytedepleted murine bone marrow cells harvested from femurs of C57BL/6 mice were plated in complete RPMI 1640 media supplemented with 20 ng/ml recombinant murine GM-CSF (Sigma, St Louis, MO, USA) and 1 ng/ml recombinant murine IL-4 (PeproTech, Rocky Hill, NJ, USA). On day 3, floating cells were gently removed and fresh medium was added.…”

“…The CTL activities was determined by a standard 4-h 51 Cr-release assay utilizing 3LL as targets. 54 Two million 3LL in 0.5 ml RPMI-1640 with 20% FCS were labeled with 200 Ci Na 51 CrO 4 (Amersham) for 2 h. The labeled cells were washed three times in serum-free medium. Ten thousand target cells were then mixed with effector cells for 4 h at 37°C at the ratio indicated.…”

The Involvement of TNF-α-Related Apoptosis-Inducing Ligand in the Enhanced Cytotoxicity of IFN-β-Stimulated Human Dendritic Cells to Tumor Cells

“…To date, DC-based tumor vaccinations in the treatment of cancer patients have shown promising results from clinical trials (5)(6)(7)(8). Apoptotic tumor cells are considered more effective than tumor debris or tumor cells alone at supplying host DCs with a source of antigenic epitopes for cross-priming autologous CD8…”