Internalization of rGel/BLyS in to CD19⁺ cells. Primary PBMNCs isolated from peripheral blood of CLL patients were incubated with either rGel (A,C) or BLyS/rGel (B,D) for 2 hours and then stained with CD19-PE antibody. Cells were then fixed and stained with gelonin antibody followed by FITC-conjugated secondary antibody. Cells were visualized using confocal microscopy (A-B) or quantitated by flow cytometry (C-D).