FACS analysis of DCs and subsequent confirmation of DC-D5LacZ fusion hybrids. (A) Electrofusion of DCs and D5lacZ cells. (Top panel) Phenotype of DCs at day 0 (black histograms) and day 8 (grey histograms) of culture. (Bottom panel) Prior to fusion, D5LacZ were intracellularly and covalently labeled with CFSE. 24 hours after fusion, adherent cells were harvested and stained with DC markers as indicated. Numbers in the upper right quadrant represent percentages of double-positive fusion hybrids. (B) MHC class I (H2-kb) and MHC class II (I-Ab) expression of DCs and DC-tumor fusion cells.