Epstein-Barr viral load, interleukin-6 and interleukin-10 levels in post-transplant lymphoproliferative disease: a nested case-control study in a renal transplant cohort

The possible correlation among Epstein-Barr virus (EBV) load, interleukin-6 (IL-6) and interleukin-10 (IL-10) levels has become an attractive issue and can provide a useful tool for diagnosis and monitoring of patients at risk for post-transplant lymphoproliferative disease (PTLD) development. At the time of diagnosis of PTLD, 11 patients were prospectively enrolled and 55 nested controls were selected from a 1800 renal transplant cohort. Real-time polymerase chain reaction (PCR) was used to quantify EBV load in peripheral blood mononuclear cells (PBMC). Serum IL-6 and IL-10 levels were determined using an enzyme-linked immunosorbent assay (ELISA). The median EBV load of PTLD cases was 17400 copies/10(6) PBMC, statistically different from controls (P=0.001). The median IL-6 level of PTLD cases was not different from controls (P=0.079). However, median IL-10 levels showed a significant difference in both groups (P < or = 0.001). The receiver-operating characteristic (ROC) curve analysis was applied to estimate the IL-10 cut-off value predictive of PTLD development. We found that 73.5 pg/ml has high sensitivity (1.00) and specificity (0.85). Also, Pearson's analysis showed a strong correlation between EBV load and serum IL-10 concentration (P < or = 0.001). This nested case-control study demonstrates that EBV load at diagnosis of PTLD correlates with IL-10 levels, and that monitoring of IL-10 can provide a less expensive and less time-consuming tool for PTLD diagnosis and close follow-up of patients at risk. Furthermore, we were able to define a cut-off value of IL-10 mostly predictive of PTLD development in this cohort. Our data suggest that serial measurements prior to PTLD development must be carried out to validate our hypothesis.