Epstein-Barr viral load as a tool to diagnose and monitor post-transplant lymphoproliferative disease

Post-transplant lymphoproliferative disease in pediatric solid organ transplant recipients

Post-transplant lymphoproliferative disease (PTLD) in solid organ transplant (SOT) recipients has become one of the most common forms of lymphoproliferation in childhood and is a serious complication of SOT. More than 90% of cases are of B-cell origin, Epstein Barr virus (EBV) positive and are mostly occurring in the early post-transplant period. Pathologically and clinically it is a heterogenous disease ranging from being responsive to reduced immunosuppression without further intervention to rapidly progressive fulminant PTLD requiring prompt initiation of therapy. Prognosis overall is favorable. Current treatment strategies as well new promising targeted immune-based therapies such as rituximab and EBV-specific cytotoxic T-lymphocytes are being discussed.

The clinical value of concomitant Epstein Barr virus (EBV)-DNA load and specific immune reconstitution monitoring after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Monitoring of EBV DNAemia after allogeneic hematopoietic stem cell transplantation (HSCT) is necessary, but not sufficient, to identify patients at risk of EBV-induced post-transplantation lymphoproliferative disorders (PTLD). Combining this with quantifying EBV-specific cellular immunity was shown to be helpful. In this study, we evaluated the value of IFNγ-Elispot assay in monitoring EBV DNAemia after HSCT.

METHODS

EBV-DNA load in whole blood was monitored at least weekly using real-time PCR in 40 recipients of HSCT. Quantitative and qualitative T-cell recoveries, including EBV-specific T-cell quantification by Elispot assay, were studied 60, 100, 180 and 360 days after HSCT.

RESULTS

Among the 35 evaluable patients, 14 (35%) presented EBV DNAemia, only 2/14 (14%) needing pre-emptive treatment with rituximab. The greatest risk factor for EBV DNAemia was the presence of anti-thymocyte globulin (ATG) (p=0.005). EBV-specific cellular immune recovery was monitored by IFNγ-Elispot assay. Using multivariate analysis, four factors were found to significantly influence IFNγ-Elispot results at defined times post-HSCT: EBV DNAemia, young age, global T-cell recovery and severe acute GVHD. In those cases where EBV DNAemia occurred and cleared spontaneously, Elispot results gave more than 1000 spot-forming cells (SFC)/10(6)PBMC.

CONCLUSION

Elispot assay may be usefully combined with EBV-DNA load monitoring to determine when a patient should receive pre-emptive treatment, or when the clinician should avoid Rituximab use which severely immunocompromises patients.

Post-transplant lymphoproliferative disorder in an adolescent masquerading as a complicated primary EBV infection

This report describes an adolescent girl with primary Epstein-Barr virus (EBV) infection in the setting of intensive immunosuppression for a cardiac transplant. She went on to develop progressive pain, weight loss and night sweats with necrosis of the tonsils over 8 weeks. The clinical impression was initially that of a complicated tonsillitis secondary to immune dysfunction. Biopsy 2 months after first presentation demonstrated diffuse B cell lymphoma consistent with post-transplant lymphoproliferative disorder (PTLD). We present this case to highlight the need for a high degree of clinical suspicion for PTLD in a population of patients who commonly experience primary exposure to EBV.

Rapid quantitative PCR assays for the simultaneous detection of herpes simplex virus, varicella zoster virus, cytomegalovirus, Epstein-Barr virus, and human herpesvirus 6 DNA in blood and other clinical specimens

Rapid diagnosis of human herpesvirus primary infections or reactivations is facilitated by quantitative PCRs. Quantitative PCR assays with a standard thermal cycling profile permitting simultaneous detection of herpes simplex virus (HSV), varicella zoster virus (VZV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), and human herpesvirus 6 (HHV6) DNA were developed and validated for diagnostic use. High specificity and sensitivity were achieved and the new PCR assays correlated well with commercial PCR assays. Twenty two thousand eight hundred sixty eight PCR tests were undertaken on specimens obtained from immunosuppressed patients. DNAemia was frequent with EBV (43.5%), HHV6 (32.4%), CMV (12.8%), and VZV (12.9%). As already described for EBV and CMV, high virus loads of HHV6 and VZV were associated with clinical symptoms and poor clinical outcome, for example, three of four patients with VZV virus loads >10(5) copies/ml died. A high proportion of lower respiratory specimens was positive for EBV- (38.8%), HHV6- (29.4%), and CMV-DNA (18.2%). For CMV, infection was confirmed in 66.7% of patients by virus isolation or positive pp65 antigenaemia. Differentiation of HHV6A, -B and HSV-1, -2 by melting curve analysis revealed that HHV6A and HSV-2 represented only 1.8% and 3.3% of all positive specimens, respectively. In conclusion, these results indicate significant improvements for the early diagnosis of primary infections or reactivations of five human herpesviruses especially in immunosuppressed patients. Detection of coinfections with multiple herpesviruses is facilitated. Quantitative results enable monitoring of virus load during antiviral therapy. A standard thermal cycling profile permits time and cost effective use in a routine diagnostic setting.

Viral infection in the renal transplant recipient

Viruses are among the most common causes of opportunistic infection after transplantation and the most important. The risk for viral infection is a function of the specific virus encountered, the intensity of immune suppression used to prevent graft rejection, and other host factors governing susceptibility. Viral infection, both symptomatic and asymptomatic, causes the "direct effects" of invasive disease and "indirect effects," including immune suppression predisposing to other opportunistic infections and oncogenesis. Rapid and sensitive microbiologic assays for many of the common viruses after transplantation have replaced, for the most part, serologic testing and in vitro cultures for the diagnosis of infection. Furthermore, quantitative molecular tests allow the individualization of antiviral therapies for prevention and treatment of infection. This advance is most prominent in the management of cytomegalovirus, Epstein-Barr, hepatitis B, and hepatitis C viruses. Diagnostic advances have not been accompanied by the development of specific and nontoxic anti-viral agents or effective antiviral vaccines. Vaccines, where available, should be given to patients as early as possible and well in advance of transplantation to optimize the immune response. Studies of viral latency, reactivation, and the cellular effects of viral infection will provide clues for future strategies in prevention and treatment of viral infections.

The post-transplant lymphoproliferative disorder-a literature review

The Epstein-Barr virus (EBV)-induced post-transplant lymphoproliferative disorder (PTLD) affects 1%-10% of all paediatric renal transplant recipients. This is a heterogeneous group of conditions characterised by EBV-driven proliferation of B-lymphocytes in the face of impaired T-cell immune surveillance. The risk factors predisposing to PTLD are becoming better understood, but its pathogenesis and myriad of clinical and histological features remain poorly defined. While new treatment modalities are being tried with variable success, regular EBV surveillance and carefully monitored reduction of immunosuppression remain the mainstay of treatment. In this review, we have presented the current knowledge of this increasingly common complication in renal transplant recipients.

Epstein-Barr virus seronegativity is a risk factor for late-onset posttransplant lymphoroliferative disorder in adult renal allograft recipients

BACKGROUND

Posttransplant lymphoproliferative disorder (PTLD) remains a difficult management issue; therefore, many studies focus on the identification of risk factors to allow for preventive strategies. We investigated risk factors for PTLD in the adult renal transplant setting.

METHODS

A single-center, matched case-control study design was used. Cases were identified from patients who underwent a first renal transplant between January 1, 1985, and December 1, 2001. Two controls were chosen per case, matched (+/-1 year) by date of transplant and graft survival. Clinical and demographic data were ascertained from medical records. Pretransplant serology for Epstein-Barr virus (EBV) and cytomegalovirus was confirmed on frozen, stored sera. Statistical analysis included univariate and multivariable examination of putative risk factors using conditional logistic regression.

RESULTS

Twenty cases of PTLD were identified, an incidence of 2.4%. Median time from transplant to diagnosis was 55 months (range, 3-168 months), with 16 cases of late-onset PTLD (>1 year posttransplant). The only significant risk in univariate analysis was EBV-negative status at transplant (risk ratio 6.0, P=0.03). In multivariable analysis, EBV-negative status remained significant (adjusted risk ratio 8.9, P=0.01). The risk related to EBV status held true when late cases were analyzed separately (adjusted risk ratio 7.1, P=0.03).

CONCLUSIONS

Pretransplant EBV-seronegative status is a strong risk for development of PTLD in adult renal allograft recipients, even in late disease. These results indicate that primary infection with EBV may have a pathogenic role in some cases of late PTLD.