Posttransplantation lymphoproliferative disorders.

Over the last decade, much has been learned about the nature of PTLD. The pivotal role of EBV infection in most cases has been established, and the pathologic description of lesions has been simplified in the current classification. It seems likely that further understanding of the molecular pathology may lead to greater ability to define optimal treatment regimens and prognosis. Quantitative PCR techniques for EBV have enhanced the capability for early diagnosis of EBV infection and PTLD and have proved useful tools for monitoring response to therapy. In particular, this technique seems to help predict when reintroduction of immunosuppression should be instituted. Several exciting new therapies are on the horizon, including use of monoclonal antibodies against B-cell surface antigens and the development of cellular therapies, such as the use of EBV-specific cytotoxic T-cell infusions. Such strategies offer the promise of controlling abnormal B-cell proliferation without the risk of allograft rejection, because the host alloresponse is not enhanced by these therapies. The role of chemotherapy and the optimal regimens required remain to be defined fully. Understanding of the cause, behavior, and optimal treatment for EBV-negative PTLD remains limited, partly because of the rarity of these lesions. There is an increasing level of interest in PTLD among clinical and basic investigators and recognition of the need for multicenter trials to define optimal prevention and treatment strategies. A degree of optimism seems warranted.