Advances in the diagnosis of renal transplant rejection

Abstract

This review attempts to cover the main areas of recent development in renal transplantation, from the viewpoint of the renal histopathologist. There are various different types of donor kidney, including the ‘non-heart beating donor' and the possibility of xenotransplantation. These pose differing problems in biopsy interpretation. Non-heart beating donor kidneys always develop severe acute tubular necrosis in the early weeks; this causes difficulty in the detection of acute rejection at this stage, which may be resolved by fine needle aspiration biopsy, urine cytology and/or repeated ‘protocol' needle core biopsy. Recent developments have improved the performance of each method, but the best course remains a subject for debate. For renal transplant pathologists, the Banff classification of renal transplant pathology is perhaps the most important practical development in recent years. This scheme has a proven use in research projects, but its role in routine practice is not yet universally accepted. It has allowed the development of the histological criteria of rejection to become an ongoing process of refinement, facilitated by wide electronic discussion through the Internet. Prospects for predicting long-term graft survival from early transplant biopsies are discussed, including the development of a ‘chronic allograft damage index'. Other areas where developments may come in the near future include studies of cytokines and adhesion molecules, lymphocyte markers, semi-automated morphometric evaluation of biopsies and monitoring the effects of novel immunosuppressive drugs.