Attenuation of apoptosis resistance in primary leukemia cells by inhibition of NFκB activation. (A) Primary leukemia cells of 6 patients with acute leukemias were obtained from bone marrow at the time of diagnosis and separated by Ficoll gradient centrifugation. Cells were treated with TRAIL (1 μg/mL) in the presence or absence of LLnL (1 hour of preincubation, untoxic dosis, respectively, for each patient, 4 to 25 μmol/L) for 6 to 12 hours (spontaneous apoptosis <35%) and apoptosis was measured by forward side scatter analysis in FACScan flowcytometer. Data are the mean of duplicates with a standard deviation less than 10%. (B) Primary bone marrow leukemia cells of a patient with common ALL were obtained as in (A). Cells were stimulated with TRAIL (1 μg/mL), anti–APO-1 (1 μg/mL) in the presence of protein A (5 ng/mL), or TNFα (0,3 μg/mL) for 6 hours in the presence or absence of LLnL (4.25 μmol/L, 1 hour of preincubation), and apoptosis was measured as in (A). Data are the mean of duplicates with a standard deviation less than 10%. Similar results were obtained in two patients.