Activation of CD160 protects against spontaneous in vitro apoptosis of CLL cells. Cell viability was assessed by annexin V/PI staining and measured with a FACSCanto. (A) CLL cells (4 × 106/mL) were treated with or without 10 μg/mL anti-CD160 (CL1-R2) for up to 5 days. Data shown are mean ± SD from 3 independent experiments (P < .001). (B) Cells were incubated with or without 10 μg/mL CL1-R2 for 18 hours and then viability was measured. Seventeen cases are presented. (C) Cell viability of all 17 cases is presented as the mean ± SEM (t test; *P < .001). (D-E) CLL cells were treated with CL1-R2, with or without a 1-hour preincubation by wortmannin (1μM) or (F) LY294002 (10μM), for 18 hours. (D) One representative experiment from 7 different patients. (E-F) Mean percentage of cell viability ± SEM (n = 7) of control versus wortmannin or LY294002 alone (E: *P = .036; F: *P < .001) and CL1-R2 alone (**P = .002; F: **P = .005); wortmannin/LY294002 plus CL1-R2 versus CL1-R2 alone (E: ***P < .001; F: ***P < .001) or wortmannin/LY294002 alone (E: ****P = .041; F: ****P = .013).
