Soluble CD30: a serum marker for Epstein-Barr virus-associated lymphoproliferative diseases

The IPTA Nashville Consensus Conference on Post-Transplant lymphoproliferative disorders after solid organ transplantation in children: III - Consensus guidelines for Epstein-Barr virus load and other biomarker monitoring

The International Pediatric Transplant Association convened an expert consensus conference to assess current evidence and develop recommendations for various aspects of care relating to post-transplant lymphoproliferative disorders after solid organ transplantation in children. In this report from the Viral Load and Biomarker Monitoring Working Group, we reviewed the existing literature regarding the role of Epstein-Barr viral load and other biomarkers in peripheral blood for predicting the development of PTLD, for PTLD diagnosis, and for monitoring of response to treatment. Key recommendations from the group highlighted the strong recommendation for use of the term EBV DNAemia instead of "viremia" to describe EBV DNA levels in peripheral blood as well as concerns with comparison of EBV DNAemia measurement results performed at different institutions even when tests are calibrated using the WHO international standard. The working group concluded that either whole blood or plasma could be used as matrices for EBV DNA measurement; optimal specimen type may be clinical context dependent. Whole blood testing has some advantages for surveillance to inform pre-emptive interventions while plasma testing may be preferred in the setting of clinical symptoms and treatment monitoring. However, EBV DNAemia testing alone was not recommended for PTLD diagnosis. Quantitative EBV DNAemia surveillance to identify patients at risk for PTLD and to inform pre-emptive interventions in patients who are EBV seronegative pre-transplant was recommended. In contrast, with the exception of intestinal transplant recipients or those with recent primary EBV infection prior to SOT, surveillance was not recommended in pediatric SOT recipients EBV seropositive pre-transplant. Implications of viral load kinetic parameters including peak load and viral set point on pre-emptive PTLD prevention monitoring algorithms were discussed. Use of additional markers, including measurements of EBV specific cell mediated immunity was discussed but not recommended though the importance of obtaining additional data from prospective multicenter studies was highlighted as a key research priority.

Immune dysregulation as a leading principle for lymphoma development in diverse immunological backgrounds

Lymphoma is a heterogeneous group of malignancies arising from lymphocytes, which poses a significant challenge in terms of diagnosis and treatment due to its diverse subtypes and underlying mechanisms. This review aims to explore the shared and distinct features of various forms of lymphoma predisposing conditions, with a focus on genetic, immunological and molecular aspects. While diseases such as autoimmune disorders, inborn errors of immunity and iatrogenic immunodeficiencies are biologically and immunologically distinct, each of these diseases results in profound immune dysregulation and a predisposition to lymphoma development. Interestingly, the increased risk is often skewed towards a particular subtype of lymphoma. Patients with inborn errors of immunity in particular present with extreme forms of lymphoma predisposition, providing a unique opportunity to study the underlying mechanisms. External factors such as chronic infections and environmental exposures further modulate the risk of lymphoma development. Common features of conditions predisposing to lymphoma include: persistent inflammation, recurrent DNA damage or malfunctioning DNA repair, impaired tumor surveillance and viral clearance, and dysregulation of fundamental cellular processes such as activation, proliferation and apoptosis. Our growing understanding of the underlying mechanisms of lymphomagenesis provides opportunities for early detection, prevention and tailored treatment of lymphoma development.

A phase I/II trial of brentuximab vedotin plus rituximab as frontline therapy for patients with immunosuppression-associated CD30+ and/or EBV + lymphomas

Treatment strategies for post-transplant lymphoproliferative disorders (PTLD) consist of response-adapted risk-stratified methods using immunosuppression reduction, immunotherapy, and chemotherapy. We investigated the efficacy of Brentuximab vedotin given concurrently with Rituximab (BV + R) once weekly for four weeks, followed by optional consolidation, and up to one year of maintenance. Among 20 assessable patients, BV + R therapy resulted in an overall response rate of 75% (95% CI 51 to 91, p = 0.044) with 60% achieving a complete response. Median time to best response was 28 days. Two-year progression-free survival and overall survival rates were 75 and 90%, respectively. Most common severe grade 3/4 treatment-related toxicities included neutropenia (40%), hypertension (30%), infection (25%), and peripheral neuropathy (15%). BV + R is a novel and effective therapeutic strategy that achieved rapid and durable remissions in previously untreated PTLD patients; however, this treatment platform requires further modification due to the high rates of treatment-related toxicity.Key pointsBrentuximab vedotin + Rituximab showed ORR and CR rates of 75 and 60% in patients with immunosuppression-associated lymphoid malignanciesHigh rates of treatment delay were attributed to treatment-related toxicity; further dosing optimization of this regimen is required.

Biomarkers for PTLD diagnosis and therapies

Post-transplant lymphoproliferative disorder (PTLD) represents a spectrum of lymphoproliferative disorders and is a serious complication of pediatric transplantation. The majority of PTLD are associated with Epstein Barr virus (EBV) and the characteristic EBV+ B cell lymphomas are the leading post-transplant malignancy in children. EBV+ PTLD remains a formidable issue in pediatric transplantation and is thought to result from impaired immunity to EBV as a result of immunosuppression. However, the key viral and immune factors that determine whether EBV+ PTLD develops remain unknown. Recently, there has been much interest in developing biomarkers in order to improve and achieve more personalized approaches, in the clinical diagnosis, management, and treatment of EBV+ PTLD. Here, we review the status of immune-, viral-, and B cell lymphoma-derived candidates for biomarkers of EBV+ PTLD.

Immunosuppressive FK506 treatment leads to more frequent EBV-associated lymphoproliferative disease in humanized mice

Post-transplant lymphoproliferative disorder (PTLD) is a potentially fatal complication after organ transplantation frequently associated with the Epstein-Barr virus (EBV). Immunosuppressive treatment is thought to allow the expansion of EBV-infected B cells, which often express all eight oncogenic EBV latent proteins. Here, we assessed whether HLA-A2 transgenic humanized NSG mice treated with the immunosuppressant FK506 could be used to model EBV-PTLD. We found that FK506 treatment of EBV-infected mice led to an elevated viral burden, more frequent tumor formation and diminished EBV-induced T cell responses, indicative of reduced EBV-specific immune control. EBV latency III and lymphoproliferation-associated cellular transcripts were up-regulated in B cells from immunosuppressed animals, akin to the viral and host gene expression pattern found in EBV-PTLD. Utilizing an unbiased gene expression profiling approach, we identified genes differentially expressed in B cells of EBV-infected animals with and without FK506 treatment. Upon investigating the most promising candidates, we validated sCD30 as a marker of uncontrolled EBV proliferation in both humanized mice and in pediatric patients with EBV-PTLD. High levels of sCD30 have been previously associated with EBV-PTLD in patients. As such, we believe that humanized mice can indeed model aspects of EBV-PTLD development and may prove useful for the safety assessment of immunomodulatory therapies.

Post-transplant lymphoproliferative disorders, Epstein-Barr virus infection, and disease in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

PTLD with the response-dependent sequential use of RIS, rituximab, and cytotoxic chemotherapy is recommended. Evidence gaps requiring future research and alternate treatment strategies including immunotherapy are highlighted.

Post-transplant lymphoproliferative disorder in pediatric intestinal transplant recipients: A literature review

Intestinal transplantation is a successful treatment for children with intestinal failure, but has many potential complications. PTLD, a clinically and histologically diverse malignancy, occurs frequently after intestinal transplantation and can be fatal. The management of this disease is particularly challenging. The rejection-prone intestinal allograft requires high levels of immunosuppression, a precondition for PTLD. While EBV infection clearly plays a role in disease pathogenesis, the relatively naïve immune system of children is another likely contributor. As a result, pediatric intestine recipients have a higher risk of developing PTLD than other solid organ recipients. Other risk factors for disease development such as molecular and genomic changes that precipitate malignant transformation are not fully understood, especially among children. Studies on adults have started to describe the molecular pathogenesis of PTLD, but the genomic landscape of the malignancy remains largely undefined in pediatric intestinal transplant patients. In this review, we describe what is known about PTLD in pediatric patients after intestinal transplant and highlight current knowledge gaps to better direct future investigations in the pediatric population.

CD30 Expression in Monomorphic Posttransplant Lymphoproliferative Disorder, Diffuse Large B-Cell Lymphoma Correlates With Greater Regulatory T-Cell Infiltration

OBJECTIVES

CD30 is a protein thought to promote cell proliferation/survival and downregulate the immune response. Twenty percent to 40% of de novo diffuse large B-cell lymphomas (DLBCLs) express CD30, and some patients have been treated with the anti-CD30 agent brentuximab. In the solid organ transplant setting, allograft regulatory T cells (Tregs) have been shown to be modulated via CD30 signaling.

METHODS

Posttransplant lymphoproliferative disorders (PTLDs) constitute a heterogeneous group of lymphomas, and since CD30 expression has been rarely formally assessed in PTLDs, we analyzed a cohort of PTLDs.

RESULTS

We found that 26 (79%) of 33 PTLDs were CD30+. Of these, 17 (77%) of 22 DLBCL monomorphic PTLDs were CD30+ compared with 56 (38%) of 148 de novo DLBCLs (P = .009). The median FoxP3+ Treg count was higher in CD30+ than in CD30- PTLDs, 3.0 vs 0 (P = .012).

CONCLUSIONS

These findings suggest a pathophysiologic link between CD30 activity and Tregs and may indicate differential expression of CD30 in B-cell lymphomas arising in the setting of immune dysregulation.

Epstein-Barr virus and renal transplantation

Epstein-Barr virus (EBV) is a gamma herpesvirus associated with diseases ranging from asymptomatic viremia to post-transplant malignancies in kidney transplant recipients. EBV specifically is associated with post-transplantation lymphoproliferative disorder (PTLD), in kidney transplant recipients, with increased risk in EBV seronegative patients with EBV seropositive donors on intensified immunosuppression. The diagnosis of PTLD relies on clinical suspicion plus tissue biopsy with polymerase chain reaction (PCR) testing of blood currently used for risk determination in high-risk recipients. Therapeutic strategies for PTLD include reduction of immunosuppression, chemotherapy and rituximab, and consideration of sirolimus-based immunosuppression. Antivirals such as ganciclovir are used to prevent reactivation of cytomegalovirus and other herpes viruses but are not onco-therapeutic. Radiation therapy or surgery is indicated for bulky, disseminated or recalcitrant disease. Prognosis varies depending on the type of malignancy identified and stage of disease.

BK Virus Load Associated with Serum Levels of sCD30 in Renal Transplant Recipients

Background. Rejection is the main drawback facing the renal transplant operations. Complicated and overlapping factors, mainly related to the immune system, are responsible for this rejection. Elevated serum levels of sCD30 were frequently recorded as an indicator for renal allograft rejection, while BV virus is considered as one of the most serious consequences for immunosuppressive treatment of renal transplant recipients (RTRs). Aims. This study aimed to determine the association of BK virus load with serum levels of sCD30 in RTRs suffering from nephropathy. Patients and Methods. A total of 50 RTRs with nephropathy and 30 age-matched apparently healthy individuals were recruited for this study. Serum samples were obtained from each participant. Real-time PCR was used to quantify BK virus load in RTRs serum, while ELISA technique was employed to estimate serum levels of sCD30. Results. Twenty-two percent of RTRs had detectable BKV with mean viral load of 1.094E + 06 ± 2.291E + 06. RTRs showed higher mean serum level of sCD30 (20.669 ± 18.713 U/mL) than that of controls (5.517 ± 5.304 U/mL) with significant difference. BK virus load had significant positive correlation with the serum levels of sCD30 in RTRs group. Conclusion. These results suggest that serum levels of sCD30 could be used as an indicator of BK viremia, and accordingly the immunosuppressive regime should be adjusted.

Elevated Serum Levels of Soluble CD30 in Ankylosing Spondylitis Patients and Its Association with Disease Severity-Related Parameters

Soluble CD30 (sCD30), a transmembrane glycoprotein that belongs to the tumor necrosis factor receptor (TNFR) superfamily, has been shown to be associated with various pathological conditions. This study was designed to measure the levels of serum sCD30 in patients with ankylosing spondylitis (AS) and to evaluate the relationships between serum sCD30 levels and other disease severity-related indexes, including bath ankylosing spondylitis disease activity index (BASDAI), ankylosing spondylitis disease activity score (ASDAS), and bath ankylosing spondylitis functional index (BASFI). Our results demonstrated significantly elevated sCD30 levels in AS patients compared to healthy controls (HCs) with mean values of 32.0 ± 12.2 and 24.9 ± 8.0 ng/mL, respectively (P^** = 0.007), suggesting a potential role of sCD30 in the pathogenesis of AS. However, no significant correlations of sCD30 with BASDAI, ASDAS, or BASFI were detected in our study (P > 0.05). Therefore, sCD30 cannot be used as a reliable marker for reflecting disease activity and functional ability of AS patients.

The tumor virus landscape of AIDS-related lymphomas

Immunodeficiency dramatically increases susceptibility to cancer as a result of reduced immune surveillance and enhanced opportunities for virus-mediated oncogenesis. Although AIDS-related lymphomas (ARLs) are frequently associated with known oncogenic viruses, many cases contain no known transforming virus. To discover novel transforming viruses, we profiled a set of ARL samples using whole transcriptome sequencing. We determined that Epstein-Barr virus (EBV) was the only virus detected in the tumor samples of this cohort, suggesting that if unidentified pathogens exist in this disease, they are present in <10% of cases or undetectable by our methods. To evaluate the role of EBV in ARL pathogenesis, we analyzed viral gene expression and found highly heterogeneous patterns of viral transcription across samples. We also found significant heterogeneity of viral antigen expression across a large cohort, with many patient samples presenting with restricted type I viral latency, indicating that EBV latency proteins are under increased immunosurveillance in the post-combined antiretroviral therapies era. Furthermore, EBV infection of lymphoma cells in HIV-positive individuals was associated with a distinct host gene expression program. These findings provide insight into the joint host-virus regulatory network of primary ARL tumor samples and expand our understanding of virus-associated oncogenesis. Our findings may also have therapeutic implications, as treatment may be personalized to target specific viral and virus-associated host processes that are only present in a subset of patients.

Post-transplant soluble CD30 levels are associated with early subclinical rejection in kidney transplantation

Several studies have shown association of high pre- or post-transplant levels of soluble CD30 (sCD30) with acute rejection and poor late kidney transplant outcome. Our goal was to investigate whether sCD30 levels at month-3 post-transplant are associated with subclinical rejection, presence of CD30(+) cells within the graft, and expression of immune response genes in peripheral blood mononuclear cells. The study comprised 118 adult first kidney graft recipients, transplanted at a single center, receiving tacrolimus in low concentration. All were submitted to a protocol biopsy at month-3. Subclinical rejection was identified in 10 biopsies and sCD30 levels ≥ 61.88 ng/mL (P = 0.004), younger recipient age (P = 0.030) and non-Caucasian ethnicity (P = 0.011) were independently associated with this outcome. Rare CD30(+) cells were present in only two biopsies. There was a correlation between sCD30 levels and CD30 gene expression in peripheral blood mononuclear cells (r = 0.385, P = 0.043). These results show that high sCD30 levels are independent predictors of graft dysfunction and may contribute to patient selection protocols by indicating those who could benefit from a more thorough evaluation.

Occurrence and prognostic relevance of CD30 expression in post-transplant lymphoproliferative disorders

Post-transplant lymphoproliferative disorders (PTLDs) are potentially fatal, often Epstein-Barr virus (EBV)-driven neoplasias developing in immunocompromised hosts. Initial treatment usually consists of a reduction in immunosuppressive therapy and/or rituximab with or without chemotherapy. However, patients who relapse do poorly, and new treatment options are warranted. With the introduction of the immunoconjugate brentuximab vedotin, the CD30 antigen has become an effectively targetable molecule. Therefore, we investigated the frequency and level of CD30 expression in PTLDs. We identified 108 patients with PTLDs diagnosed during 1994-2011, of whom 62 had adequate paraffin-embedded tissue for tissue microarray construction. Immunohistochemical expression of CD30 was consistently detected in all types of PTLD (overall 85.25%), including the monomorphic subtypes, and was correlated with a more favorable outcome. For diffuse large B-cell lymphoma (DLBCL)-type PTLD this was regardless of EBV status, and remained significant in multivariate analysis. Cell-of-origin had no independent prognostic value in our series of DLBCL PTLD.

The Biology and Clinical Utility of EBV Monitoring in Blood

Epstein-Barr virus (EBV) DNA in blood can be quantified in peripheral blood mononuclear cells, in circulating cell-free (CCF) DNA specimens, or in whole blood. CCF viral DNA may be actively released or extruded from viable cells, packaged in virions or passively shed from cells during apoptosis or necrosis. In infectious mononucleosis, viral DNA is detected in each of these kinds of specimens, although it is only transiently detected in CCF specimens. In nasopharyngeal carcinoma, CCF EBV DNA is an established tumor marker. In EBV-associated Hodgkin lymphoma and in EBV-associated extranodal NK-/T-cell lymphoma, there is growing evidence for the utility of CCF DNA as a tumor marker.

Malignancies after pediatric kidney transplantation: more than PTLD?

Post-transplant lymphoproliferative disease (PTLD) is the most frequent malignant complication of transplantation in childhood. Even with modern post-transplant immunosuppressive strategies, 1-2% of all kidney transplant recipients will develop PTLD within the first 5 years after transplantation, and the risk remains high even thereafter as long as immunosuppression is required. In addition to PTLD, adult kidney transplant recipients have an increased incidence of other immunosuppression-related malignancies, such as non-melanoma skin cancer or Kaposi's sarcoma. It is foreseeable that pediatric transplant recipients will face similar complications during their adult life. Not only immunosuppression but also other risk factors have been identified for some of these malignancies. Strategies addressing these risk factors during childhood may contribute to life-long cancer prevention. Furthermore, early recognition and regular screening may facilitate early diagnosis and treatment, thereby reducing transplant-related morbidity. In this review we focus on malignant complications after renal transplantation and discuss known risk factors. We also review current screening strategies for malignancies during post-transplant follow-up.

Post-transplant lymphoproliferative disease (PTLD): risk factors, diagnosis, and current treatment strategies

Post-transplant lymphoproliferative diseases (PTLD) are heterogeneous lymphoid disorders ranging from indolent polyclonal proliferations to aggressive lymphomas that complicate solid organ or hematopoietic transplantation. Risk factors for PTLD include viral infections, degree of immunosuppression, recipient age and race, allograft type, and host genetic variations. Clinically, extra-nodal disease is common including 10-15 % presenting with central nervous system (CNS) disease. Most PTLD cases are B cell (5-10 % T/NK cell or Hodgkin lymphoma), while over one-third are EBV-negative. World Health Organization (WHO) diagnostic categories are: early lesions, polymorphic, and monomorphic PTLD; although in practice, a clear separation is not always possible. Therapeutically, reduction in immunosuppression remains a mainstay, and recent data has documented the importance of rituximab +/- combination chemotherapy. Therapy for primary CNS PTLD should be managed according to immunocompetent CNS paradigms. Finally, novel treatment strategies for PTLD have emerged, including adoptive immunotherapy and rational targeted therapeutics (e.g., anti-CD30 based therapy and downstream signaling pathways of latent membrane protein-2A).

Interleukin 28B gene polymorphisms and Epstein-Barr virus-associated lymphoproliferative diseases

OBJECTIVES

Single-nucleotide polymorphisms (SNPs) near the interleukin (IL) 28B gene encoding a type III interferon (IFN-λ) are the most important genetic predictors of treatment response to hepatitis C virus (HCV). This retrospective study was undertaken to determine any association between IL28B SNPs and the development of viraemia in Epstein-Barr virus (EBV)-driven acute infectious mononucleosis (IM) and post-transplant lymphoproliferative disease (PTLD).

METHODS

Genomic DNA extracted from plasma from 45 EBV seropositive controls and 46 acute IM, 23 non-PTLD (transplant) and 21 PTLD patients was tested by PCR for 2 SNPs within IL28B. EBV DNA levels were tested in IM and PTLD samples by a real-time quantitative PCR.

RESULTS

No significant differences were seen in SNP frequencies at rs12979860 and rs8099917 in IM and PTLD patients compared to EBV seropositive controls and transplant patients. EBV DNA levels were lower in IM and PTLD patients with CC (a favourable genotype in HCV) at rs12979860 compared to non-CC genotypes (p = 0.055). Acute IM patients with CC had significantly lower levels of EBV DNA in plasma compared to those with non-CC genotypes (p = 0.011).

CONCLUSIONS

Genotype CC may influence anti-viral responses of IFN-λ, thereby allowing better control of EBV viraemia during lymphoproliferation, particularly in IM.

Posttransplant lymphoproliferative disease after pediatric solid organ transplantation

Patients after solid organ transplantation (SOT) carry a substantially increased risk to develop malignant lymphomas. This is in part due to the immunosuppression required to maintain the function of the organ graft. Depending on the transplanted organ, up to 15% of pediatric transplant recipients acquire posttransplant lymphoproliferative disease (PTLD), and eventually 20% of those succumb to the disease. Early diagnosis of PTLD is often hampered by the unspecific symptoms and the difficult differential diagnosis, which includes atypical infections as well as graft rejection. Treatment of PTLD is limited by the high vulnerability towards antineoplastic chemotherapy in transplanted children. However, new treatment strategies and especially the introduction of the monoclonal anti-CD20 antibody rituximab have dramatically improved outcomes of PTLD. This review discusses risk factors for the development of PTLD in children, summarizes current approaches to therapy, and gives an outlook on developing new treatment modalities like targeted therapy with virus-specific T cells. Finally, monitoring strategies are evaluated.

Plasma markers of B-cell activation and clonality in pediatric liver and hematopoietic stem cell transplant recipients

BACKGROUND

Transplant recipients are at risk of posttransplant lymphoproliferative disease (PTLD).

METHODS

Thirty-six pediatric transplant recipients were evaluated (18 hematopoietic stem cell and 18 liver recipients; 12 had PTLD). We studied 207 longitudinal plasma samples from these recipients for three markers of B-cell activation or clonality: immunoglobulin free light chains (FLCs), soluble CD30 (sCD30), and monoclonal immunoglobulins (M-proteins).

RESULTS

Kappa FLCs, lambda FLCs, and sCD30 were elevated in 20.8%, 28.0%, and 94.2% of plasma specimens, respectively. Free light chain and sCD30 levels increased significantly 1.18 to 1.82 fold per log10 Epstein-Barr virus (EBV) load in peripheral blood. Five PTLD cases manifested elevated FLCs with an abnormal kappa/lambda ratio, suggesting monoclonal FLC production. M-proteins were present in 91% of PTLD cases versus 50% to 67% of other recipients with high or low EBV loads (P=0.13). Concordance of FLCs, M-proteins, and PTLD tumor light chain restriction was imperfect. For example, one PTLD case with an IgG lambda M-protein had a tumor that was kappa restricted, and another case with an M-protein had a T-cell PTLD. In an additional case, an IgM kappa M-protein and excess kappa FLCs were both detected in plasma at PTLD diagnosis; although the tumor was not restricted at diagnosis, kappa restriction was present 5 years later when the PTLD relapsed.

CONCLUSIONS

Plasma markers of B-cell dysfunction are frequent after transplantation and associated with poor EBV control. These abnormal markers may be produced by oligoclonal B-cell populations or PTLD tumor cells and could potentially help identify recipients at high risk of PTLD.

Posttransplant lymphoproliferative disease after lung transplantation

Posttransplant lymphoproliferative disease (PTLD) after lung transplantation occurs due to immunosuppressant therapy which limits antiviral host immunity and permits Epstein-Barr viral (EBV) replication and transformation of B cells. Mechanistically, EBV survives due to latency, escape from cytotoxic T cell responses, and downregulation of host immunity to EBV. Clinical presentation of EBV may occur within the lung allograft early posttransplantation or later onset which is more likely to be disseminated. Improvements in monitoring through EBV viral load have provided a means of earlier detection; yet, sensitivity and specificity of EBV load monitoring after lung transplantation may require further optimization. Once PTLD develops, staging and tissue diagnosis are essential to appropriate histopathological classification, prognosis, and guidance for therapy. The overall paradigm to treat PTLD has evolved over the past several years and depends upon assessment of risk such as EBV-naïve status, clinical presentation, and stage and sites of disease. In general, clinical practice involves reduction in immunosuppression, anti-CD20 biologic therapy, and/or use of plasma cell inhibition, followed by chemotherapy for refractory PTLD. This paper focuses upon the immunobiology of EBV and PTLD, as well as the clinical presentation, diagnosis, prognosis, and emerging treatments for PTLD after lung transplantation.

Gene expression analysis of host spleen responses to Marek's disease virus infection at late tumor transformation phase

Marek's disease is a viral neoplastic disease of chickens caused by Marek's disease virus (MDV). Gene expression patterns have been investigated at different MDV infection stages, but there is limited research about the late tumor transformation phase. In this experiment, 44K Agilent chicken genome-wide expression microarrays were used to profile differential expression in tumorous spleens (TS) from severely morbid chickens and apparently normal spleens from survivors (SS) after MDV infection and expression in noninfected spleens (NS) from controls. There were 4,317 differentially expressed (DE) genes in TS versus NS. However, no DE genes were detected in SS versus NS, suggesting that maintenance of, or return to, homeostasis of gene activity in survivor spleens. Downregulated genes in tumorous spleens mainly enriched in the cytokine-cytokine receptor interaction pathway, and commonly investigated genes in Marek's disease study, IL6, IL18, IFNA, and IFNG were nondifferentially expressed, which indicates host inflammatory response was impaired. The IL10 and TNFRSF8 genes were upregulated in tumorous spleens. We speculated that IL10 might be exploited by MDV to escape from host immune surveillance, as reported for Epstein-Barr virus, which stimulated T cells secreting IL10 to subvert immune response. Previous study reported that transcription from TNFRSF8 promoter could be enhanced by MDV oncogene Meq. In this study, the increased expression of TNFRSF8 indicated interaction between MDV and TNFRSF8, which might facilitate pathogenesis and tumor transformation. The expression of many members in IGF system was changed in tumorous compared with noninfected spleens. The downregulation of IGFBP7 was considered to be associated with MD lymphoma transformation. Gene expression change of multiple regulatory pathways indicated their involvements in facilitating tumor transformation.

CXCL13 as a novel marker for diagnosis and disease monitoring in pediatric PTLD

Posttransplant lymphoproliferative disease (PTLD) is a severe complication of immunosuppressive treatment in organ-grafted children. Early diagnosis of PTLD is hampered by both unspecific clinical symptoms and lack of easy accessible markers. The homeostatic chemokine CXCL13, which plays a crucial role in B-cell homing and lymphoid organ development, is expressed in some lymphomatous diseases. This study aims to investigate whether serum CXCL13 (sCXCL13) levels correlate with occurrence and regression of PTLD in pediatric solid-organ graft recipients. Serum samples from PTLD patients (n = 21), patients with Epstein-Barr virus (EBV) reactivation (n = 18), and healthy age-matched controls (n = 19) were tested for CXCL13 using a commercially available ELISA kit. sCXCL13 levels were significantly higher in PTLD patients than in healthy children. PTLD patients had also higher sCXCL13 values than pediatric solid-organ recipients with EBV reactivation. An increase in sCXCL13 levels was observed from EBV reactivation to PTLD diagnosis in most cases. Elevated sCXCL13 levels were detected up to 2 years prior to PTLD diagnosis and correlated well with response to cytoreductive treatment in individual patients. sCXCL13, thus, may be a readily available surrogate marker for the diagnosis of PTLD and for monitoring of response to treatment in patients with initially elevated sCXCL13 levels.

Circulating antibody free light chains and risk of posttransplant lymphoproliferative disorder

Posttransplant lymphoproliferative disorder (PTLD) is a major complication of solid-organ transplantation. With human immunodeficiency virus infection (an analogous immunosuppressive state), elevated kappa and lambda immunoglobulin free light chains (FLCs) in peripheral blood are associated with increased risk of lymphoma. To assess the role of B-cell dysfunction in PTLD, we measured circulating FLCs among Canadian transplant recipients, including 29 individuals with PTLD and 57 matched transplant recipients who were PTLD-free. Compared with controls, PTLD cases had higher kappa FLCs (median 1.53 vs. 1.07 times upper limit of normal) and lambda FLCs (1.03 vs. 0.68). Using samples obtained on average 3.5 months before PTLD diagnosis, cases were more likely to have polyclonal FLC elevations (i.e. elevated kappa and/or lambda with normal kappa/lambda ratio: odds ratio [OR] 4.2, 95%CI 1.1-15) or monoclonal elevations (elevated kappa and/or lambda with abnormal ratio: OR 3.0, 95%CI 0.5-18). Strong FLC-PTLD associations were also observed at diagnosis/selection. Among recipients with Epstein-Barr virus (EBV) DNA measured in blood, EBV DNAemia was associated with FLC abnormalities (ORs 6.2 and 3.2 for monoclonal and polyclonal elevations). FLC elevations are common in transplant recipients and associated with heightened PTLD risk. FLCs likely reflect B-cell dysfunction, perhaps related to EBV-driven lymphoproliferation.

Posttransplant lymphoproliferative disease following liver transplantation

PURPOSE OF REVIEW

Despite contemporary immunosuppressive regimens, posttransplant lymphoproliferative disease (PTLD) remains a major complication after liver transplantation. This review highlights advances in the understanding of the pathophysiology, diagnosis, and management of PTLD in liver transplant recipients.

RECENT FINDINGS

The spectrum of PTLD after liver transplant ranges from polymorphic lymphoproliferation to high-grade monoclonal lymphoma and is usually related to outgrowth of lymphocytes infected with Epstein-Barr virus (EBV). Risk factors for PTLD include EBV-seronegativity of the recipient, young age, intensity of immunosuppression, and the first year posttransplant. Measurement of EBV load by quantitative polymerase chain reaction assays is an important aid in the surveillance and diagnosis of PTLD although the specificity for PTLD is only about 50% (specificity for EBV is ∼100%). In patients diagnosed with PTLD, management options include reduction of immunosuppression, rituximab, combination chemotherapy, and adoptive immunotherapy. Outcomes have improved because rituximab has been incorporated into treatment regimens, and immunotherapy approaches show promise.

SUMMARY

PTLD is a significant complication after liver transplantation, particularly in children. Advances in early detection approaches have aided in the diagnosis and management of PTLD, but further research to identify better predictive biomarkers is needed to improve risk-based treatment strategies.