Lenalidomide enhances intracellular delivery of oligonucleotides in anti-CD20 immunoliposomes. (A) B CLL cells were incubated with rituximab-coated immunoliposomal FAM-ODN for 1 hour at 37°C. Cells were washed and incubated with lenalidomide for 1, 4, and 24 hours. At the end of the incubation time, cells were washed 3 times and visualized on a Nikon fluorescence microscope (original magnification, ×200). (B) Lenalidomide-enhanced delivery of oligonucleotides requires CD20 antigen binding and internalization. CLL cells were incubated with rituximab-, trastuzumab-, or alemtuzumab-coated immunoliposomal FAM-ODN for 1 hour at 37°C. Cells were washed and incubated with lenalidomide for an additional 24 hours. At the end of the incubation time, cells were washed 3 times and visualized on a Nikon fluorescence microscope (original magnification, ×200).