ROR1-mediated antibody internalization.

<p>Confocal immunofluorescence microscopy demonstrated internalization of mouse anti-human ROR1 mAb 2A2 by pre-B ALL cell line 697. The cells were incubated with mAb 2A2 for 1 h on ice followed by incubation at 37°C for 0–2 h in the absence or presence of PAO. Subsequently, the cells were fixed, permeabilized, stained with DyLight 649-conjugated goat anti-mouse IgG pAbs, co-stained with DAPI, and analyzed with a Zeiss LSM 510 UV confocal microscope (objective 63×). In the absence of PAO, mAb 2A2 (pink) was found uniformly on the cell surface at 0 h (top panel) and predominantly in cytoplasmic clusters at 2 h (middle panel). No internalization at 2 h was seen in the presence of PAO (bottom panel). DAPI staining the nucleus is seen in blue. (Original magnification×2).