Milatuzumab immunoliposome increases CD74 on the surface of CLL cells and induces cell death. (A) Mean fluorescent intensity (MFI) of surface CD74 in CLL patient cells either untreated, treated with 25 μg/mL anti-Fc, or 5 μg/mL milatuzumab with or without 25 μg/mL anti-Fc for 1 hour. Histogram shown is representative of 14 patients. (B left) Mean fluorescent intensity of CD74 in CLL patient cells either untreated, treated with 25 μg/mL anti-Fc, or 5 μg/mL milatuzumab with or without 25 μg/mL anti-Fc for 1 hour (N = 14; P = .0003). (Right) MFI of CD20 in CLL patient cells either untreated, or treated with 5 μg/mL milatuzumab with or without 25 μg/mL anti-Fc for 1 hour (N = 14; P = .14). (C) MFI of CD74 in CLL patient cells either untreated, or treated with empty liposome or milatuzumab-immunoliposome (mila-IL) for 1 hour (N = 4; P = .0003). (D) Viability by PI staining in CLL patient cells either untreated, or treated with empty liposome, IgG-immunoliposome (IgG-IL), mila-IL, 25 μg/mL anti-Fc, or 5 μg/mL milatuzumab with 25 μg/mL anti-Fc for 24 hours (N = 11; P = .0003).