CD22-targeted liposomes bind to and kill malignant cells from patients with B-cell lymphomas or leukemias. (A) Binding of ^BPCNeuAc liposomes to patient B cells. Shown are representative samples from 1 healthy donor and 6 patients with HCL, CLL, or splenic MZL. Lymphocytes were gated based on the forward- and side-scatter characteristics. B-cell populations detected with anti–human CD19 were analyzed for binding of anti–human CD22 (top row), naked liposomes (middle row), and CD22-targeted ^BPCNeuAc liposomes (bottom row). CD22-bright HCL (red circle) was distinguished from normal B cells (black circle). (B) Correlation of binding of ^BPCNeuAc liposomes with CD22 or CD20 expression on the B-cell lymphomas. The diagonal lines represent linear regression that was analyzed using Prism software and the values of goodness of fit (r²) are indicated (n = 25). (C) Cytotoxicity of the dox-loaded ^BPCNeuAc liposomes toward malignant B cells. Top panel shows results of the viability of blood lymphocytes evaluated by the standard MTT assay after treatments of dox-loaded naked or ^BPCNeuAc liposomes with dox concentrations at 10 or 40μM. Cells left untreated (Unt) were defined as the maximal cell viability. Complete cell killing was determined from the Triton X-100 lysed cells (Tri). Bottom panel shows percentages (means of triplicate ± SD) of the viable blood lymphocytes after treatment with dox-loaded naked or ^BPCNeuAc liposomes. *P < .05 compared with control treatments of naked liposomes. Representative data from 1 of 4 samples are shown.