Killing of K562 and ML-2 cells by NK lysates.

(A) Killing of tumor cells by NK lysates. Target cells were incubated with 0.3 μg, 1 μg, 30 μg, or 100 μg total protein of the NK lysates for 4 hours at 37°C in 5% CO₂. Dead cells were stained with PI and analyzed by flow cytometry. (B) Kinetics of the tumor cell lysis. Target cells were incubated with 100 μg total protein of the NK lysates for 0, 1, 2, 4, or 8 hours at 37°C in 5% CO₂. Dead cells were stained with PI and analyzed by flow cytometry.