CD40L and IL-4 resulted in less death of CLL cells in the absence of NK cells (Fig. 1a), consistent with previous reports [20], and significantly reduced NK cell specific lysis of primary CLL cells at all E:T ratios tested (1:1 P < .01, 5:1 P < .001, 10:1 P < .05) (Fig. 1a and b). Here, CD40LG is linked to B-cell chronic lymphocytic leukemia.