Epstein-Barr viral load and disease prediction in a large cohort of allogeneic stem cell transplant recipients

Background. We wanted to determine the clinical significance and predictability of Epstein-Barr virus (EBV) infections among a large cohort of recipients of allogeneic, unselected stem cell transplants. Methods. During 1988-1999, a total of 5479 consecutive serum samples obtained during 406 transplantations performed in Helsinki, Finland, were retrospectively analyzed by quantitative polymerase chain reaction for the presence of EBV DNA. Results. Overall, EBV DNA was noted in at least 1 serum sample for 57 patients (14.0%), of whom 22 (5.4%) were found to have progressively increasing and ultimately high ( 150,000 copies/mL) EBV DNA levels (median level, 179,000 copies/mL). In addition, 16 patients (4.0%) had low EBV DNA levels ( median level, 3260 copies/mL) in isolated sera before death. Among the transplant recipients who survived, transient EBV DNAemia (median level, 3110 copies/mL), which apparently corresponded to asymptomatic EBV infection, was noted in 19 patients (4.7%). Conclusions. Low-level EBV DNA positivity in serum occurs relatively frequently after stem cell transplantation and may subside without specific treatment. However, high EBV DNA levels (i.e., 150,000 copies/mL) are strong predictors for the development of posttransplantation lymphoproliferative disease, are not spontaneously reversible, and should be treated immediately. If the EBV DNA level is >= 50,000 copies/mL, the patient can be classified as having life-threatening EBV infection.