Specifically, culturing CLL B cells with activated T lymphocytes (199); C3d-coated Ag, IL-4, and BAFF (200); CD40L + IL-4 (88, 124, 201); and TLR9 agonist + IL-15 (202) can lead to AID expression. The gene discussed is CD40LG; the disease is B-cell chronic lymphocytic leukemia.