Bortezomib enhances R-CDC but not R-ADCC in Raji cells. (A) Raji cells were incubated with either diluent or bortezomib at 10-, 20-, or 50-nM concentration for 12, 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) Control- and bortezomib-pretreated Raji cells were suspended in the medium (2 × 10⁶ in 2 mL) with 10 μg/mL rituximab and 10% human AB serum as a source of the complement and incubated for 5, 15, and 45 minutes. Then, they were washed twice with PBS and incubated with anti–C5b-9 antibody as described in “Flow cytometry.” (C) Raji cells were seeded into a 96-well flat-bottom plate (5 × 10⁴ cells/well). Then, rituximab (1, 10, or 100 μg/mL) or a control medium was added for 15 minutes followed by addition of peripheral blood mononuclear cells used as effector cells at an effector-to-target (E/T) cell ratio of 100:1. After incubation (6 hours, 37°C), assay was developed using Cytotoxicity Detection Kit^PLUS. *P < .05 (Student t test).