The role of the B-cell receptor–antigen interaction in B-cell trogocytosis. (A) MD4 B cells were incubated for 1 hour at 37°C with the following target cells labeled with the fluorescent lipophilic dye PKH26:J558L (filled histogram), J558LmHEL (black line histogram), or J558LmHEL in the presence of 100 μg/mL sHEL (gray line histogram). The B cells were then analyzed for PKH26 acquisition. Histograms show the levels of PKH26 fluorescence on B220⁺ B cells. (B) Coincubation of MD4 B cells with PKH26-labeled J558LmHEL cells in the presence of increasing concentrations of sHEL for 1 hour at 37°C. Ordinate values correspond to the percentage of staining due to the capture of PKH26 relative to the level of staining on the PKH26-labeled J558LmHEL target cells.