Killing and perforin binding on the surface of tumor cells from 6 AML patients by NK lysates.

Target cells and 100 μg total protein of the NK lysates were coincubated for 4 hours at 37°C. After staining dead cells with PI and perforin on the cell surface with an FITC-labeled perforin antibody, cells were analyzed in FL1 versus FL2 dot plots by flow cytometry. K562 cells served as a positive control.