Reversal of anergy following culture in vitro is associated with recovery of PRDM1 induction in nonresponsive CLL samples. Nonresponsive CLL samples (n = 8) were left to “recover” in vitro for up to 4 days, and then, (A) iCa²⁺ mobilization following anti-IgM treatment was measured. The time of anti-IgM stimulation (down arrow) and the set threshold above which the percentage of responsive cells was calculated (dotted line) are shown. (B) Induction of PRDM1 after treatment with CpG-ODN for 16 hours was measured by western blot. Levels of PRDM1 in a responsive CLL clone treated with CpG-ODN for 16 hours are shown for comparison.