Characterization of cells prepared by dendritic cell-tumor cell fusion.

Dendritic cells (DCs) are professional antigen-presenting cells currently being discussed as a potent tool for antitumor vaccination strategies. The approach consisting of the in vitro generation of DC-tumor cell hybrids may be advantageous for individualized vaccines since there is no need for the determination of MHC-restricted tumor-associated antigens recognized by T cells. As recent vaccination studies gave varying results, we tested the impact of the fusion treatment on the cells used. Polyethylene glycol-induced fusion, as well as electrofusion, proved to be suitable for generating hybrid cells although at a low frequency. Of note, both methods also gave rise to DCs having phagocytosed apoptotic tumor cells. The expression of surface molecules relevant for specific T cell stimulation was not altered by the fusion procedure and the DCs were still functionally active as demonstrated by the secretion of IL-12 and the uptake of antigen. The cells were able to induce a tumor-specific T cell response in vitro and therefore deserve further investigation as potent tools for immunotherapy trials.