In support of this idea, the present study newly defines that resting human peripheral blood B cells: 1) express multiple cytotoxic transmembrane TNFSF ligands such as TNF, FasL, LT-α1β2 and/or TRAIL; and 2) mediate a powerful innate apoptotic killing of virtually all types of leukemia and carcinoma cells and normal proliferating endothelial cells and fibroblasts through simultaneous engagement of these ligands. Here, TNFSF10 is linked to leukemia.