IL-21 induces granzyme B secretion by B-CLL cells, which is synergistically enhanced by CpG ODN and anti-BCR. B-CLL cells from 3 patients were isolated and purified to a percentage of at least 99.9% based on CD19 expression. The cells were cultured at 37°C on 96-well ELISPOT plates for granzyme B detection at 100 000 cells/well and in the presence of different B-cell activators alone or with IL-21. After 16 hours, plates were developed and dots counted. Every condition was run in triplicate. (A) Individual ELISPOT plate from 1 representative experiment of 3 is shown. (B) Average spot numbers from 1 representative experiment of 3 are depicted. Error bars indicate SD. (C) B-CLL cell survival after 4 days of incubation with anti-BCR or CpG ODN alone () or with IL-21 (▪) was flow cytometrically detected using annexin V, anti-CD19, and PI staining. Averages from 3 independent experiments are shown. Error bars indicate SEM.