Cytotoxic activity of NK-92-scFv(FRP5)-ζ cells.

Lysis of K562 human erythroleukemic cells (A), ErbB2-negative MDA-MB468 (B), and ErbB2-overexpressing MDA-MB453 human breast carcinoma cells (C) by NK-92 and transduced NK-92-scFv(FRP5)-ζ cells was analyzed in europium (Eu³⁺) release assays. Target cells were labeled with Eu³⁺ solution by electroporation and then incubated with NK-92-scFv(FRP5)-ζ (○) or parental NK-92 cells (●) at different E/T ratios for 2 hours. Release of Eu³⁺ complexes into the medium was determined by fluorimetric analysis and served as a measure for target-cell lysis. Specific lysis was calculated as described in “Materials and methods.”