Figure 2. MB314 and MB311 mediated effector functions. (A, B) CDC reactivity against two Lewis Y positive tumor cell lines was tested using a FACS based approach. Tumor cells were incubated with different concentrations of antibodies in the presence of human complement for 1 h. As complement source frozen human serum was used. Cytotoxicity against SKBR-3 cells (A) or OVCAR-3 cells (B) was quantified by FACS™ analysis using a live/dead cell stain. Gated 7-AAD+ population (dead cells) as percentage of the whole population are plotted vs. the logarithm of the antibody concentration and fitted using a sigmoidal four parameter fit using GraphPad Prism 4 software. Mean and SD of triplicates are shown. (C, D) ADCC activity against two Lewis Y positive tumor cell lines was tested in a ⁵¹Cr release cell lysis assay. ⁵¹Cr labeled target cells (T) were incubated with effector cells (PBMCs from a healthy volunteer donor, E) at indicated E:T ratios for 16 h. Supernatants were counted for released ⁵¹Cr using a γ-counter. Specific lysis (%) was plotted against the logarithm of the antibody concentration (ng/ml) and fitted using a sigmoidal four parameter fit using GraphPad Prism 4 software.