Inhibition of granule-mediated killing with an antiperforin antibody.
(A) Dose-dependent inhibition of hemolysis; 30 μg total protein of the NK lysates were incubated for 10 minutes with different concentrations of the antiperforin antibody and then 100 μL of a 2% erythrocyte suspension was added. After incubation for 30 minutes at 37°C, the supernatant was harvested and analyzed for hemoglobin in a photometer at 412 nm. (B) Inhibition of granule-mediated killing of K562 cells; 100 μg total protein of the NK lysates were incubated for 10 minutes with PBS, an isotype control antibody (100 μg/mL), or the antiperforin antibody (100 μg/mL) and then 20 μL of K562 cells with 2 × 106 cells/mL were added. After incubation for 4 hours at 37°C, the dead cells were stained with PI and analyzed by flow cytometry.
