DC acquisition of HLA-Bw4 molecules.

DCs were cultured on glass cover slips on a monolayer of nonirradiated melanoma cells. The cocultures were processed for immunofluorescence and confocal microscopy 20 hours later. (A, B) HLA-DR molecules expressed by DCs were visualized using an HLA-DR-FITC mAb and displayed as green staining. (A, B) HLA-Bw4 molecules were visualized by specific primary mAbs followed by a Texas red–conjugated second antibody and displayed as red staining. (A, B) Optically merged confocal images showed the colocalization, displayed as yellow staining, of the HLA-DR marker with HLA-Bw4 molecules on the cell surface of DCs. The transfer of cell membrane molecules starts from the point of contact between DCs and melanoma cells (B, indicated by arrows).