CD95/CD95L does not mediate HC apoptosis.
Expression of surface CD95L was examined by FACS analysis (A) in untreated (shaded histogram) and IFN-α–treated (open histogram) HCs. (B) HCs were treated with CD95-agonist mAb (CH11; 200 ng/mL; ▴), control IgM (200 ng/mL; ▪), or left untreated (♦) and assessed for viability. (C) IFN-α–treated HCs were incubated with CD95-blocking mAb (ZB4; 500 ng/mL; ▴) or with class-specific control Ig (500 ng/mL; ▪) and compared with HCs cultured in the absence of IFN-α (♦). The percentages of viable DiOC6-positive/PI-negative cells (B,C) are shown. The results are a representative of 4 experiments involving cells from 2 different HCL patients. The results were similar in all 4 experiments but were not pooled because, as in Figure 1, the time taken for appreciable killing differed markedly between cases (6-14 days).
