CD40LG and B-cell chronic lymphocytic leukemia: Upregulation of pro-survival B-Cell Lymphoma-2 family members occurs on stimulation with T cells or with monocyte-derived cells such as macrophages or nurse-like cells (NLCs).1 Although the tumor necrosis factor (TNF) receptor ligand family member CD40L can account largely for the survival effect by T cells,2 several factors have been described to have a role in the CLL cell survival effect governed by monocyte-derived cells.3,4 A prominent factor in this context is the TNF family member a proliferation-inducing ligand (APRIL).4