Next, using the optimized culture conditions, we analyzed the proliferative response of fresh negatively selected B cells isolated from a cohort of well characterized CLL patients, under informed consent, including clinical data, cell morphology, flow cytometry - including ZAP70 expression status-, FISH and IGHV mutational status, as these factors may impact the cell response to stimulation22,28,30,31. This evidence concerns the gene ZAP70 and B-cell chronic lymphocytic leukemia.