Peripheral blood samples were obtained from patients with diagnosis of B-CLL after informed consent approved by the Institutional Ethics Committee. Normal blood samples were taken from healthy volunteers. Mononuclear cells were isolated by density gradient centrifugation on F/H. B cells were purified with CD19-specific MACS beads (Miltenyi, Bergisch Gladbach, Germany). Cells were cultured at 37uC in a 5% CO 2 atmosphere in standard medium with 10% fetal calf serum.