In order to compare the immunophenotype of proliferating CLL cells found in vivo with the ex-vivo stimulated CLL cells, we analyzed the modulation of the expression of CD38, CD49d, CD62L, CXCR4, CXCR5 and CCR7 in primary CLL cells after 48 hours of co-culture as compared to CLL cells in suspension (Figure 2B). This evidence concerns the gene CD38 and B-cell chronic lymphocytic leukemia.