Using CLL cells from 26 patients and 5 healthy controls, we found that both CXCL12 (mean 6.9 ± 1% SEM, P < 0.0001) and CpG (positive control) (4.6 ± 0.8%, P < 0.0001) induced significant IL-10 production by CLL cells, as measured by intracellular staining and ELISA (Figures 1B,C; Figure S4A in Supplementary Material). This evidence concerns the gene IL10 and B-cell chronic lymphocytic leukemia.