The Syk inhibitor R406 induces apoptosis of CLL cells in cocultures with NLC. (A) Displayed are contour plots that depict CLL cell viability, after staining with DiOC6 and PI (horizontal and vertical axes, respectively). The viable cell population is characterized by bright DiOC6 staining and PI exclusion, and is gated in the lower right corner of each contour plot. The percentage of viable cells is displayed above each of these gates. CLL cells were cocultured with NLC in presence or absence of the Syk inhibitor R406, as indicated above the plots. In this case, R406 reduced CLL cell viability in NLC cocultures from 94.8% to 45.4% at 24 hours, and from 84.7% to 48.3% at 48 hours. (B) The bars represent the mean relative viability of CLL cells cocultured with NLC (control) compared with CLL cells cocultured with NLC plus R406. Viabilities were normalized to the relative viability of control samples at the respective time points (100%), to account for differences in spontaneous apoptosis in samples from different patients. Viability was assessed after 24 and 48 hours. Displayed are the mean (± SEM) viabilities from 24 patient samples. *P < .01.
