Effects of anti-CD20/22 bsAbs on proliferation of B-lymphoma cell lines. The cultures were started at approximately 105 cells/mL in 48-well tissue culture plates so that the untreated control cells can continuously proliferate at log-phase for 3 to 4 days. The viable cell populations were then determined by the MTT assay. (A) The inhibitory potencies of 3 different anti-CD20/22 bsAbs were determined in D1-1 cells. The cells were cultured in complete RPMI medium containing varying concentrations (up to 10 μg/mL) of hA20xhLL2 (●), hA20Fab-LL2scFv (■), or hA20IgG-(RFB4scFv)2 (▴) for 3 days and viable populations were determined. Error bars represent standard deviations of duplicate tests. (B) The growth inhibitory effects of the anti-CD20/22 bsAbs with or without α-IgM were compared. D1-1 cells were cultured in medium containing 10 nM of the parental mAb (hA20 or epratuzumab), both parental mAbs (hA20 + epratuzumab), or each of the 3 different anti-CD20/22 bsAbs as indicated under the x-axis, in the absence (shaded bars) or presence (clear bars) of SA-AD4 (1 nM), for 3 days and viable populations were determined. The results shown were normalized to those of the corresponding controls in which none of the parental mAbs or bsAbs was added. Error bars represent standard deviations of duplicate tests.
