PKCβII activity regulates BCR-induced survival of CLL cells. Cells from the same CLL patients with high and low PKCβII activity, as described in Figure 6, were incubated with 10 μg/mL F(ab′)2 fragments of goat anti–human IgM. (A) Aliquots of stimulated (dashed line) and control (solid line) CLL cells were taken at 1-day intervals and were stained with PI and DiOC6 to determine viability using flow cytometry with a fixed time setting of 30 seconds to quantitate the number of cells per unit volume.37 The data presented in each graph are representative of a single experiment using 4 CLL patients with high and 4 CLL patients with low levels of PKCβII activity. Each experiment was performed in triplicate. (B) Percentage difference (mean ± SD) in cell viability between stimulated and control cells with high and low PKCβII activity in CLL patients after BCR stimulation. Cell viability was measured at day 3 of culture. Tests for statistical significance were performed using a Mann-Whitney U test (n = 5). (C) Influence of BCR crosslinking (BCR-XL) and bryostatin on Mcl-1 expression in CLL cells with different levels of PKCβII activity (representative Western blots of experiments with cells from 3 CLL patients with high and 3 CLL patients with low levels of PKCβII activity). CLL cells were stimulated with 10 nM bryostatin or with BCR crosslinking for 24 hours.
