FIG. 7.
IL-18 causes death in freshly isolated human NK cells. (A) Isolated primary NK cells from a healthy donor were cultured for 24 h with or without increasing concentrations of rhIL-18. IL-18-mediated cell death was measured by counting dead cells using a trypan blue exclusion assay. (B) Isolated human NK cells were cultured for 24 h in the presence of rhIL-18 (10 ng/ml) with or without the addition of anti-FasL antibodies or TNF-α- or TRAIL-neutralizing antibodies (1 μg/ml each). IL-18-mediated cell death was measured by counting dead cells using a trypan blue exclusion assay. (C) Human NK cells were treated as described above and stained with FITC-conjugated annexin V and PI and analyzed by flow cytometry. The results are representative of three independent experiments done on three different donors.