CD40 stimulation of peripheral blood B-CLL results in an apoptosis gene expression profile similar to lymph node B-CLL. (A) Apoptosis gene expression profile was investigated by RT-MLPA in PB samples of 11 freshly isolated B-CLL patient samples without culturing (▪) and after 3 days of culturing on either 3T3 cells (▽) or CD40L-transfected 3T3 cells (□). Data plus standard deviation are presented as in Figure 2. (B) The expression of Bcl-xL, Bfl-1/A1, Bid, and Noxa are shown at day 1, 3, and 5 of culturing on 3T3 cells (▿) or CD40L-transfected 3T3 cells (•). Statistical analysis of day 0 versus day 1 samples showed that in all cases the CD40L-treated values were significantly different (P < .01). In case of Noxa, there was also a small but significant decrease for the 3T3 control cells (P = .019), and a more pronounced effect for CD40L-treated cells (P = .004; **P = .015, difference between 3T3 and CD40L-treated cells). Error bars indicate standard deviation. (C) Western blot of t = 0 samples in comparison with CD40L-treated cells at day 3 for Noxa, Mcl-1, and Bcl-xL showed that Noxa protein levels decrease, whereas Mcl-1 and Bcl-xL increase. For B-CLL sample 226 the Mcl-1 levels at t = 0 were in fact undetectable (see also Figure 3).