Serial measurement of Epstein-Barr viral load in peripheral blood in pediatric liver transplant recipients during treatment for posttransplant lymphoproliferative disease

Background. Few data are available describing the natural history of the Ep stein-Barr virus (EBV) viral load after the diagnosis of EBV-associated pos ttransplant lymphoproliferative disease (PTLD). Accordingly, we prospective ly followed the EBV viral load after the diagnosis of EBV/PTLD in seven ped iatric orthotopic liver transplant recipients. Methods. EBV viral loads were serially measured by quantitative competitive polymerase chain reaction of the peripheral blood from pediatric patients with PTLD and correlated with the clinical course of these children. Viral loads >200 genome copies/10(5) peripheral blood lymphocytes were considered consistent with an increased risk of PTLD. Viral loads <200 obtained durin g treatment for PTLD were considered evidence of "clearance" of EBV; subseq uent loads >200 were considered evidence of virologic "rebound." Results. The mean EBV viral load at the time of diagnosis of PTLD was 1029. All patients "cleared" their EBV viral load during the treatment of PTLD; patient and graft survival in this series was 100%. The mean time to cleara nce of EBV from the peripheral blood (18.8 days) was similar to the mean ti me to onset of first rejection (13.8 days). EBV viral load at the time of d iagnosis of rejection after PTLD was always <100. A rebound in the EBV vira l load to >200 was noted in five of seven patients a median of 3.5 months ( range 2.3-13 months) after the diagnosis of EBV/PTLD. How ever, none of the se children has had any evidence of PTLD recurrence. Conclusions. Clearance of the EBV viral load from the peripheral blood seem s to correlate with restoration of the host's immune response as noted both by the regression of the PTLD and the onset of rejection. Late rebound of the EBV viral load is common and does not seem to predict disease recurrenc e.