Induction of specific cytolytic T lymphocytes using fusions of hepatocellular carcinoma (HCC) patient-derived dendritic cells and allogeneic HCC cell line

BACKGROUND/AIMS: To assess the ability of hepatocellular carcinoma (HCC) patient-derived dendritic cells (DCs) fused with allogeneic HCC cell line to activate autologous lymphocytes to generate specific cytotoxic T lymphocytes (CTL) in vitro. METHODOLOGY: DCs were obtained by culturing adherent peripheral blood mononuclear cells (PBMC) from HCC patients in the presence of 100 microg/L recombinant human granulocyte/ macrophage- colony stimulating factor (rhGM-CSF) and 20 microg/L interleukin-4 (rhIL-4) for 1 week in vitro. DCs were fused with allogeneic HCC cell line HepG2 cells using polythyleneglycol (PEG), and the fusion cells were designated as DCs/HepG2. By labeling DCs and HepG2 with green and red fluoresceins, respectively, the cellular fusion was examined under fluorescence microscope. The ability of DCs/HepG2 to stimulate proliferation and differentiation of autologous lymphocytes was assessed by MTT method, and the specific killing efficacy of DCs/HepG2-induced CTL against HepG2 was evaluated. RESULTS: HCC patient-derived DCs expressed a certain level of CD1a, HLA-DR, CD54, CD80 and CD86. Fluorescence microscopic examination demonstrated that co-incubation of DCs and HepG2 in the presence of PEG lead to generation of DCs/HepG2. In the mixed lymphocyte reaction assay, DCs/HepG2 had a significantly greater ability to activate proliferation of autologous lymphocytes, as compared with DCs alone, DCs plus HepG2, HepG2 alone and medium control (P<0.05). The DCs/HepG2-activated CTL showed a potent specific killing efficacy against HepG2 cells. CONCLUSIONS: Fusions of HCC patient-derived DCs and allogeneic HCC cell line could efficiently stimulate autologous lymphocytes to generate tumor-specific CTL in vitro. It might represent a promising approach of immunotherapy for HCC.