Proteasome inhibitors enhance R-CDC. (A) Daudi, DoHH2, and Ramos cells were incubated with either diluent or bortezomib at indicated concentrations for 24 or 48 hours. Then, equal numbers of cells (105/well) were incubated for 1 hour with serial dilutions (from 1 to 100 μg/mL) of rituximab in the presence of 10% human AB serum as a complement source. Cell viability was measured with an MTT assay. The survival of cells is presented as percentage of corresponding diluent- or bortezomib-pretreated cells without rituximab. (B) Raji cells were incubated with either diluent, epoxomycin, MG-132, or PSI at indicated concentrations for 24 or 48 hours. Then, equal numbers of cells (105/well) were incubated for 1 hour with serial dilutions (from 1 to 100 μg/mL) of rituximab in the presence of 10% human AB serum as a complement source. Cell viability was measured with an MTT assay. The survival of cells is presented as percentage of corresponding diluent- or proteasome inhibitor–pretreated cells without rituximab. (C) Freshly isolated cells from patients with diffuse large B-cell lymphoma (DLBCL), marginal zone lymphoma (MZL), and chronic lymphocytic leukemia (CLL) were incubated with either diluent or bortezomib at indicated concentrations for 24 or 48 hours. Then, equal numbers of cells (105/well) were incubated for 1 hour with rituximab in the presence of 10% human AB serum as a complement source. Cell viability was measured with an MTT assay. The survival of cells is presented as percentage of corresponding diluent- or bortezomib-pretreated cells without rituximab. *P < .05 (Student t test).
