Treatment with 1540-14 renders CLL cells of Ad-CD154-treated patients sensitive to CD95-mediated apoptosis. The bars represent the data obtained from CLL blood samples obtained before (□) or 24 hours after (▪) infusion of autologous Ad-CD154 CLL cells. After isolation, the CLL cells were cultured in one of the following conditions: (1) medium alone; (2) medium with CH11; (3) 1540-20 at 4 μM; (4) 1540-14 at 4 μM; (5) CH11 and 4 μM 1540-20; or (6) CH11 and 4 μM 1540-14. After 24 hours, the proportions of viable CLL cells were assessed by flow cytometry. Data are presented as the relative viability, which represents the proportion of viable CLL cells in the treatment wells relative to that of CLL cells cultured in medium alone. The viability of the CLL cells in the cultures containing only medium was always in excess of 80%. Addition of CH11 alone did not reduce the viability of pretherapy or posttherapy CLL cells relative to that of control cultures (data not shown). The error bars indicate the standard error about the mean values obtained from duplicate wells. Similar results were obtained in 2 independent experiments. The brackets with P < .05 indicate that there is a significant difference between (1) the relative viability of CLL cells obtained after Ad-CD154 gene therapy when treated with 1540-14 relative to that of such cells when treated with 1540-20, or (2) the relative viability of CLL cells obtained after Ad-CD154 gene therapy when treated with both CH11 and 1540-14 relative to that of such cells when treated with 1540-14 alone. An asterisk (^*) indicates that the CLL cells obtained after Ad-CD154 gene therapy had a significantly lower relative viability than that of CLL cells obtained prior to therapy when treated with CH11 and 1540-14.