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Presents information on a study which demonstrated fusions of human breast cancer cells and dendritic cells (DC) activate T cell responses against autologous tumors. Function of breast tumor cell/DC fusions; Materials and methods of the study; Phenotype of human breast tumor cell/DC fusions; Results and discussion.

Background: Human hepatocellular carcinoma (HCC) cells express WT1 and/or carcinoembryonic antigen (CEA) as potential targets for the induction of antitumor immunity. In this study, generation of cytotoxic T lymphocytes (CTL) and regulatory T cells (Treg) by fusions of dendritic cells (DCs) and HCC cells was examined. Methods: HCC cells were fused to DCs either from healthy donors or the HCC patient and investigated whether supernatants derived from the HCC cell culture (HCCsp) influenced on the function of DCs/HCC fusion cells (FCs) and generation of CTL and Treg. Results: FCs coexpressed the HCC cells-derived WT1 and CEA antigens and DCs-derived MHC class II and costimulatory molecules. In addition, FCs were effective in activating CD4+ and CD8+ T cells able to produce IFN-γ and inducing cytolysis of autologous tumor or semiallogeneic targets by a MHC class I-restricted mechanism. However, HCCsp induced functional impairment of DCs as demonstrated by the down-regulation of MHC class I and II, CD80, CD86, and CD83 molecules. Moreover, the HCCsp-exposed DCs failed to undergo full maturation upon stimulation with the Toll-like receptor 4 agonist penicillin-inactivated Streptococcus pyogenes. Interestingly, fusions of immature DCs generated in the presence of HCCsp and allogeneic HCC cells promoted the generation of CD4+ CD25high Foxp3+ Treg and inhibited CTL induction in the presence of HCCsp. Importantly, up-regulation of MHC class II, CD80, and CD83 on DCs was observed in the patient with advanced HCC after vaccination with autologous FCs. In addition, the FCs induced WT1- and CEA-specific CTL that were able to produce high levels of IFN-γ. Conclusion: The current study is one of the first demonstrating the induction of antigen-specific CTL and the generation of Treg by fusions of DCs and HCC cells. The local tumor-related factors may favor the generation of Treg through the inhibition of DCs maturation; however, fusion cell vaccination results in recovery of the DCs function and induction of antigen-specific CTL responses in vitro. The present study may shed new light about the mechanisms responsible for the generation of CTL and Treg by FCs. [ABSTRACT FROM AUTHOR]

Abstract: We have reported that fusions of patient-derived dendritic cells (DC) and autologous breast cancer cells induce T-cell responses against autologous tumors. However, the preparation of fusion cells requires patient-derived tumor cells, and these are not always available in the clinical setting. In the present study, we explore an alternative approach to constructing DC-breast cancer fusion vaccine by using breast caner-cell lines. DC generated from HLA-A*0201-positive donor were fused to HLA-A*0201+ allogeneic MCF7 breast cancer cells. These fusion cells co-expressed tumor-associated antigens and DC-derived costimulatory and MHC molecules. Both CD4 and CD8 T cells were activated by the fusion cells as demonstrated by the production of IFN-γ. The fusion cells induced strong antigen-specific cytotoxic T lymphocytes (CTL) activity against their parent cells. The lysis of targets was restricted by HLA-A*0201, since killing was blocked by the anti-HLA-A2 mAb. Similar CTL activity against HLA-A*0201-positive targets was induced when T cells were cocultured with fusions of DC and HLA-A*0201-negative allogeneic BT20 breast cancer cells. In addition, administration of T cells stimulated by DC-breast cancer fusion cells regressed 7-day-old tumors and rendered mice free of disease up to 90 days. These results suggest that tumor-cell lines can be used as a fusion partner in the construction of DC-tumor fusion vaccine. Such fusion cells hold promise since they can be used as a vaccine for active immunotherapy or as stimulators to activate and expand T cells for adoptive immunotherapy. [Copyright &y& Elsevier]

Multiple myeloma (MM) cells express certain tumour-associated antigens (TAAs) that could serve as targets for active-specific immunotherapy. The aim of the present study was to test the MM/dendritic cell (DC) fusion as a vaccination strategy. We fused MM cells with DC to generate fusion cells (FCs) and tested their antigen presenting cell (APC) function in mixed lymphocyte reactions and cytotoxicity assays. First, the HS Sultan and SK0-007 HAT sensitive human MM cell lines and DCs generated from peripheral blood of normal donors were fused in the presence of 50% polyethylene glycol to form FCs. Next, tumour cells freshly isolated from patients were similarly fused with autologous DCs to generate FCs. The FCs demonstrated a biphenotypic profile, confirmed both by flow-cytometry and dual immunofluorescence microscopy. These FCs induced MM-specific cytotoxicity. FCs, but not MM cells or DCs alone, were potent stimulators of autologous patient T cells. More importantly, FC-primed autologous peripheral blood mononuclear cells demonstrated major histocompatibility complex-restricted MM-specific cytolysis. These studies therefore demonstrated that MM/DC FC can trigger an autologous immune response to MM cells and formed the framework for a clinical trial currently underway. [ABSTRACT FROM AUTHOR]