LETTER

Top Letter References

In the April issue, Limaye and colleagues report on detection of Epstein-Barr virus (EBV) DNA in sera from solid-organ transplant recipients with posttransplant lymphoproliferative disease (PTLD) (4). Detection of cell-free EBV DNA appeared to be a sensitive and specific marker for the early detection of PTLD following solid-organ transplantation in this study as well as in another (2). Five of six transplant recipients were shown to have EBV DNA in serum at the time of diagnosis, and in two of three patients for whom stored sera were analyzed EBV DNA was detected 8 and 52 months, respectively, prior to the diagnosis of PTLD.

We analyzed the detection of cell-free EBV DNA in plasma from six patients with histopathologically proven PTLD after allogeneic bone marrow transplantation (BMT) or peripheral blood stem cell transplantation (PBSCT). All patients presented with fever and lymphadenopathy on a median of day 84 (range, day 44 to day 160) after transplantation. Plasma samples obtained during the clinical course of PTLD were available from five patients. Only plasma specimens obtained before the development of PTLD could be analyzed for the sixth patient. By nested PCR with primers derived from the EBNA-1 gene of the virus (1), cell-free EBV DNA was detected in all five patients for whom plasma samples were available during PTLD (Table 1). Furthermore, for four patients detection of cell-free EBV DNA preceded the onset of PTLD by a median of 25 days (range, 7 to 50 days). Thus, detection of EBV DNA in plasma seemed to be predictive of the development of PTLD in these patients (Table 2). This observation might be important as administration of virus-specific cytotoxic T lymphocytes has been described to be effective for treatment of patients with PTLD (3).

To further analyze the specificity of our assay, we investigated 96 plasma samples from 41 BMT or PBSCT patients with detectable EBV DNA in peripheral blood leukocytes and without clinical signs of PTLD. Eight plasma samples from six patients tested positive for EBV DNA in our assay. Thus, specificity of the plasma PCR with randomly collected plasma samples from BMT or PBSCT patients in this analysis was 91.7% and did not reach the 100% reported by Limaye et al. for 16 control-matched patients after solid-organ transplantation.

Despite the relatively small number of patients with PTLD in our analysis, we suggest that detection of cell-free EBV DNA in patients after BMT or PBSCT is a sensitive and specific marker for ongoing PTLD in the presence of fever and lymphadenopathy. As EBV PCR with cell-free specimens is easy to perform, it might be useful for monitoring of patients at risk of developing PTLD after solid-organ transplantation or BMT or PBSCT. In the absence of clinical symptoms suggestive of PTLD, detection of EBV DNA in plasma may be predictive of later development of lymphoma in some if not all patients after BMT or PBSCT. In summary, we were able to confirm the high sensitivity of detection of EBV DNA in plasma from patients with PTLD after allogeneic BMT or PBSCT as described by Limaye and colleagues for patients after solid-organ transplantation.