The extent of downregulation of CXCR4 expression in CLL by both soluble IgM and IgD stimulation (decrease to 78 and 85 % of the basal expression) was substantially lower than that observed in healthy donor-derived B cells (decrease to 20 and 15 % of the basal expression, Fig. 3a). The gene discussed is CD40LG; the disease is B-cell chronic lymphocytic leukemia.