Fig. 3

Expression of CD95 (Fas) by NK-92 cells and effects of Fas-ligation on their viability. Fas-sensitive Jurkat cells were used as positive controls for Fas expression and death after a day of Fas ligation. Dead cells are indicated by binding of FITC-labeled annexin V to phosphatidyl serine that is externalized in the plasma membranes of dying cells. A Surface expression of Fas/CD95. 1 Expression of Fas by Jurkat cells. 1a Unlabeled cells. 1b Cells labeled with mAb anti-CD95 Fas. 2 Expression of Fas by non-irradiated NK-92 cells. 2a&2b are as indicated for 1a & 1b. 3 Expression of Fas by NK-92 cells irradiated with 10 Gy. 3a&3b are as indicated for 1a &1b. B Induction of death with control IgM or IgM anti-Fas in overnight culture. By Overton subtraction, the conversion from annexin V-low to annexin V-high cells (apoptotic and necrotic) was 52% for Jurkat cells, 5.8% for non-irradiated NK-92 cells, and 9.2% for the irradiated NK-92 cells (*p < 0.05). C Changes in cellular size (forward scatter) in response to irradiation and Fas-ligation. 1 Non-irradiated cells cultured with media, IgM isotype, or anti-Fas IgM. 2 Cells 1 day after 10 Gy irradiation, cultured with media, IgM isotype, or anti-Fas IgM