[Inducing hepatocellular carcinoma-specific cytotoxic T lymphocyte response using formed by fusion of FastDCs and allogeneic human hepatocellular carcinoma cells]

Abstract

Objective: To fuse human hepatocellular carcinoma (HCC) cells with mature monocyte-derived dendritic cells (FastDC) and to observe in vitro the function of the fused cells in stimulating autologous T cells proliferation and inducing HCC-specific cytotoxic T lymphocyte (CTL) response.

Methods: CD14(+) cells were isolated and purified from the peripheral blood of a healthy HLA-A2 blood donor and cultured in fresh dendritic cell complete medium for 24 h, then proinflammatory mediators were supplemented for another 24 h, thus generating mature dendritic cell (FastDCs). The FastDCs were fused with human HCC cells of the line HCCLM3 to generate novel dendritoma. T cells were isolated from selected CD14(-) cells and then divided into 4 groups to be stimulated with dendritoma cells, DCs, HCCLM3 cells, and mixed DCs-HCCLM3 cells respectively for 96 hours. 18 hours before the end of cultivation (3)H-TdR was added into the culture fluid. Scintillation counter was used to measure the cpm values. CD8(+)T cells were isolated from CD14(-) cells, and added with different stimulating cells radiated by (60)Co and IL-2, IL-6, and IL-7. The values of IFN-gamma in the supernatants of the culture fluid of CD8(+)T cells with dendritoma cells, DCs, HCCLM3 cells, and mixed DCs-HCCLM3 cells was measured. HCCLM3, K562, HLE, self monocytes labeled with Na(2)(51)CrO(4) were added with effector cells, gamma-scintillation counter was used to measure the cpm value so as to calculate the killing ability of CTL.

Results: The CTLs activated by dendritoma cells specifically killed the HCCLM3 cells in the context of MHC class I and acted less vigorously against the control target cells. The CTLs activated by dendritoma cells were stronger in killing HCCLM3 cells than DCs, HCCLM3 cells, and mixed DCs-HCCLM3 cells (all P < 0.05). The killing activity was decreased on the HCCLM3 cells incubated with anti-HLA-ABC antibody. Three, five, and seven days after co-cultivation the value of IFN-gamma in the supernatants of the culture fluid of CD8(+)T cells with fused cells, DCs, HCCLM3 cells, and mixed DCs-HCCLM3 cells increased gradually, especially in the supernatants of the culture fluid of CD8(+)T cells with dendritoma cells (400 pg/ml +/- 60 pg/ml 3 days after, 1030 pg/ml +/- 160 pg/ml 5 days after, and 1260 pg/L +/- 180 pg/L 7 days after).

Conclusion: The novel dendritomas formed with HCCLM3 cells and mature FastDCs from healthy human peripheral blood CD14(+) monocytes are potent stimulators for CD8(+)T cells in inducing HCCLM3 cell-specific lysis. With shorter time required for in vitro DC development, the rapid method of generation of dendritoma is more economic and may represent a new strategy for immunotherapy of hepatocellular carcinoma.