A variety of innovations, such as techniques for early detection of Epstein-Barr (EBV) and CMV infections, bone marrow augmentation, the adjunct use of the interleukin-2 antagonist daclizumab, lower initial tacrolimus doses with target trough levels of 10 to 15 ng/ ml, and most recently allograft irradiation were considered to have contributed to improved results in this indication over time (Abu- Elmagd et al., Ann Surg 2001; 234:404).