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 (>50,000 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., >50,000 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 >or=50,000 copies/mL, the patient can be classified as having life-threatening EBV infection.