The infusion induced changes in circulating bystander, non-infected CLL cells and both acute and long-term clinical responses. The changes in bystander CLL cells were similar to those observed in CLL cells following ligation of CD40, which included enhanced or de novo expression of CD54, CD80, and CD86, allowing the modified CLL cells to function more effectively in presenting antigens to autologous T cells. Following CD40 ligation, CLL cells are induced to express CD95 and DR5 and to undergo changes in expression of pro- and anti-apoptotic proteins, ultimately favoring apoptosis in the CLL cells.