Humoral rejection (antibody-mediated rejection; AMR) of organ transplants has been established to constitute a separate rejection entity and in recent years accurate biopsy-based (C4d) and serological criteria for this rejection type have been defined to provide a valuable basis for targeted treatment (Sis, B et al. 2010). It has become evident that a considerable proportion of recipients develop features of AMR late after transplantation, a process culminating in chronic irreversible tissue damage, graft dysfunction and loss (Mauiyyedi, S et al. 2001). Indeed, there are studies suggesting that newly formed donor-specific antibodies (DSA) represent the primary cause of late graft loss (Einecke, G et al. 2009).