Figure 1. Binding activity MB314 and MB311. (A) Binding of MB311 and MB314 to the Lewis-Y positive tumor cell line SKBR-3 was determined by flow cytometry. Geometric Mean fluorescence intensity (MFI) was plotted vs. the logarithm of the antibody concentration and fitted using a sigmoidal four parameter fit using GraphPad Prism 4 software for calculation of EC₅₀ values. Mean and SD of triplicates are shown. Binding of 100µg/ml MB311 (dark gray line) or MB314 (black line) to purified human NK-cells expressing the FcγRIII variant V/F (B), to the FcγRIII variant F/F (C) and the FcγRIII variant V/V (D). Results obtained with medium only are shown as light gray lines.