Clinical and pathological features of post-transplant lymphoproliferative disorders (PTLD)

Recent advancements in hematopoietic stem cell transplantation in Taiwan

Hematopoietic stem cell transplantation (HSCT) can cure malignant and nonmalignant hematological disorders. From 1983 to 2022, Taiwan performed more than 10,000 HSCT transplants. The Taiwan Blood and Marrow Transplantation Registry collects clinical information to gather everyone's experience and promote the advances of HSCT in Taiwan to gather everyone's experience and promote advances of HSCT in Taiwan. Compared with matched sibling donors, transplants from matched unrelated donors exhibited a trend of superior survival. In Taiwan, transplant donors showed remarkable growth from unrelated (24.8%) and haploidentical (10.5%) donors. The number of older patients (17.4%; aged ≥61 years) who underwent transplantation has increased markedly. This review summarizes several significant developments in HSCT treatment in Taiwan. First, the use of Anti-thymocyte globulin (ATG) and intravenous busulfan regimens were important risk factors for predicting hepatic sinusoidal obstruction syndrome. Second, a new, machine learning-based risk prediction scoring system for posttransplantation lymphoproliferative disorder has identified five risk factors: aplastic anemia, partially mismatched related donors, fludarabine use, ATG use, and acute skin graft-versus-host disease. Third, although the incidence of idiopathic pneumonia syndrome was low (1.1%), its mortality rate was high (58.1%). Fourth, difficult-to-treat mantle cell and T-cell lymphomas treated with autologous HSCT during earlier remission had higher survival rates. Fifth, treatment of incurable multiple myeloma with autologous HSCT showed a median progression-free survival and overall survival of 46.5 and 70.4 months, respectively. Sixth, different haploidentical transplantation strategies were compared. Seventh, caution should be taken in administering allogeneic HSCT treatment in older patients with myeloid leukemia with a Charlson Comorbidity Index ≥3 because of a higher risk of nonrelapse mortality.

Epstein-Barr virus infection: the micro and macro worlds

Epstein‒Barr virus (EBV) is a DNA virus that belongs to the human B lymphotropic herpesvirus family and is highly prevalent in the human population. Once infected, a host can experience latent infection because EBV evades the immune system, leading to hosts harboring the virus for their lifetime. EBV is associated with many diseases and causes significant challenges to human health. This review first offers a description of the natural history of EBV infection, clarifies the interaction between EBV and the immune system, and finally focuses on several major types of diseases caused by EBV infection.

Validation of a Post-Transplant Lymphoproliferative Disorder Risk Prediction Score and Derivation of a New Prediction Score Using a National Bone Marrow Transplant Registry Database

BACKGROUND

We externally validated Fujimoto's post-transplant lymphoproliferative disorder (PTLD) scoring system for risk prediction by using the Taiwan Blood and Marrow Transplant Registry Database (TBMTRD) and aimed to create a superior scoring system using machine learning methods.

MATERIALS AND METHODS

Consecutive allogeneic hematopoietic cell transplant (HCT) recipients registered in the TBMTRD from 2009 to 2018 were included in this study. The Fujimoto PTLD score was calculated for each patient. The machine learning algorithm, least absolute shrinkage and selection operator (LASSO), was used to construct a new score system, which was validated using the fivefold cross-validation method.

RESULTS

We identified 2,148 allogeneic HCT recipients, of which 57 (2.65%) developed PTLD in the TBMTRD. In this population, the probabilities for PTLD development by Fujimoto score at 5 years for patients in the low-, intermediate-, high-, and very-high-risk groups were 1.15%, 3.06%, 4.09%, and 8.97%, respectively. The score model had acceptable discrimination with a C-statistic of 0.65 and a near-perfect moderate calibration curve (HL test p = .81). Using LASSO regression analysis, a four-risk group model was constructed, and the new model showed better discrimination in the validation cohort when compared with The Fujimoto PTLD score (C-statistic: 0.75 vs. 0.65).

CONCLUSION

Our study demonstrated a more comprehensive model when compared with Fujimoto's PTLD scoring system, which included additional predictors identified through machine learning that may have enhanced discrimination. The widespread use of this promising tool for risk stratification of patients receiving HCT allows identification of high-risk patients that may benefit from preemptive treatment for PTLD.

IMPLICATIONS FOR PRACTICE

This study validated the Fujimoto score for the prediction of post-transplant lymphoproliferative disorder (PTLD) development following hematopoietic cell transplant (HCT) in an external, independent, and nationally representative population. This study also developed a more comprehensive model with enhanced discrimination for better risk stratification of patients receiving HCT, potentially changing clinical managements in certain risk groups. Previously unreported risk factors associated with the development of PTLD after HCT were identified using the machine learning algorithm, least absolute shrinkage and selection operator, including pre-HCT medical history of mechanical ventilation and the chemotherapy agents used in conditioning regimen.

Posttransplant Lymphoproliferative Disorders Presenting as an External Nasal Deformity: A Case Report

INTRODUCTION

Posttransplant lymphoproliferative disorder (PTLD) is a serious disease that usually occurs after solid organ transplant and stem cell transplant. Posttransplant lymphoproliferative disorder often involves the head and neck, but it is rare to present as a nasal deformity. Here, we describe a case of external nasal enlargement resulting from PTLD.

CASE REPORT

A 40-year-old man presented with an enlarged external nose half a year ago. The nasal ala thickened, and the external nose was gradually enlarged, accompanied by bilateral nasal obstructions. A biopsy was taken under endoscopy procedure, and the result suggested a diagnosis of PTLD.

DISCUSSION

Posttransplant lymphoproliferative disorder usually appears in lymphoid tissues that form Waldeyer's rings or cervical lymph nodes in the head and neck. The early involvement of other head and neck subpoints is considered rare. This case is the first report of PTLD presenting as an external nasal deformity. The symptoms and clinical manifestations of PTLD in otorhinolaryngology are usually diverse and nonspecific but are early symptoms in the clinical course of PTLD.

Epstein-Barr virus (EBV) reactivation and therapeutic inhibitors

Epstein-Barr virus (EBV) is a ubiquitous human virus which infects almost all humans during their lifetime and following the acute phase, persists for the remainder of the life of the individual. EBV infects B lymphocytes leading to their immortalisation, with persistence of the EBV genome as an episome. In the latent phase, EBV is prevented from reactivating through efficient cytotoxic cellular immunity. EBV reactivates (lytic phase) under conditions of psychological stress with consequent weakening of cellular immunity, and EBV reactivation has been shown to occur in a subset of individuals with each of a variety of cancers, autoimmune diseases, the autoimmune-like disease, chronic fatigue syndrome/myalgic encephalitis and under other circumstances such as being an inpatient in an intensive care unit. Chronic EBV reactivation is an important mechanism in the pathogenesis of many such diseases, yet is rarely tested for in immunocompetent individuals. This review summarises the pathogenesis of EBV infection, EBV reactivation and its role in disease, and methods which may be used to detect it. Known inhibitors of EBV reactivation and replication are discussed, including drugs licensed for treatment of other herpesviruses, licensed or experimental drugs for various other indications, compounds at an early stage of drug development and nutritional constituents such as vitamins and dietary supplements.

EBV-PTLD, Adenovirus, and CMV in Pediatric Allogeneic Transplants With Alemtuzumab as Part of Pretransplant Conditioning: A Retrospective Single Center Study

The risk of viral infections and reactivation occurring in the setting of pediatric allogeneic hematopoietic stem cell transplantation is a concern in the pediatric patient, especially with the use of Alemtuzumab (Campath) as a conditioning agent. The purpose of this study was to determine the incidence of Epstein-Barr virus posttransplant lymphoproliferative disorder (EBV-PTLD), cytomegalovirus (CMV), and adenovirus among pediatric recipients of alemtuzumab at our institution. We found that EBV-PTLD occurred in 2.1% of transplants (1 matched unrelated donor [MUD] recipient), CMV reactivation occurred in 12.5% of transplants (4 MUD and 2 matched related donor [MRD] recipients) with disseminated CMV in 2.1% of cases (1 MRD recipient), and adenovirus infection occurred in 8.3% of the total transplants (2 MUD and 2 MRD recipients). Alemtuzumab continues to be used as a method of graft-versus-host disease and graft failure prevention among pediatric recipients of hematopoietic stem cell transplantation and seems to be safer than previously reported. At our institution, alemtuzumab has not increased the risk for EBV-PTLD, CMV infection, or adenovirus.

Sinonasal Posttransplant Lymphoproliferative Disorder in Pediatric Lung Transplant Patients

OBJECTIVE: To evaluate sinonasal manifestations of posttransplant lymphoproliferative disorder (PTLD) in the pediatric lung transplant population.

STUDY DESIGN AND METHODS: Case series of children less than 18 years presenting with PTLD after pulmonary transplantation at St Louis Children's Hospital between Jan 1, 1990 and Dec 31, 2003.

RESULTS: Two hundred eighty-two lung transplants were performed in 246 children. Thirty-two cases of histopathologically confirmed PTLD were identified with 8 (25%) presenting in the head and neck. Sinonasal PTLD was the most common site of head and neck involvement (63%), with 40% of patients presenting with occult disease. All patients with sinonasal PTLD had longstanding nasal polyposis related to cystic fibrosis ( P = 0.07).

CONCLUSIONS: This is, to our knowledge, the first report identifying an increased frequency of sinonasal PTLD after pediatric pulmonary transplantation, particularly in children with cystic fibrosis and associated nasal polyposis. Because sinonasal PTLD may be asymptomatic, this region should receive close scrutiny on surveillance evaluations.

Posttransplantation lymphoproliferative disease: proposed imaging classification

Posttransplantation lymphoproliferative disease (PTLD) is the second most common tumor in adult transplant recipients. Most cases of PTLD are attributed to Epstein-Barr virus. Decreased levels of immunosurveillance against this tumor virus as a result of immunosuppressive regimens are thought to account for most cases of PTLD. Histologically, PTLD ranges from relatively benign lymphoid hyperplasia to poorly differentiated lymphoma, and tissue sampling is required to establish the subtype. The frequency of PTLD varies depending on the type of allograft and immunosuppressive regimen. PTLD has a bimodal manifestation, with most cases occurring within the first year after transplantation and a second peak occurring 4-5 years after transplantation. Patients are often asymptomatic or present with nonspecific symptoms, and a mass visible at imaging may be the first clue to the diagnosis. Imaging plays an important role in identifying the presence of disease, guiding tissue sampling, and evaluating response to treatment. The appearance of PTLD at imaging can vary. It may be nodal or extranodal. Extranodal disease may involve the gastrointestinal tract, solid organs, or central nervous system. Solid organ lesions may be solitary or multiple, infiltrate beyond the organ margins, and obstruct organ outflow. Suggestive imaging findings should prompt tissue sampling, because knowledge of the PTLD subtype is imperative for appropriate treatment. Treatment options include reducing immunosuppression, chemotherapy, radiation therapy, and surgical resection of isolated lesions.

Risk of diffuse large B-cell lymphoma after solid organ transplantation in the United States

Non-Hodgkin lymphoma arising in the context of immunosuppression is an important adverse outcome after solid organ transplantation. Diffuse large B-cell lymphoma (DLBCL) is the most commonly diagnosed subtype of post-transplantation non-Hodgkin lymphoma, but few studies of transplant recipients have examined subtype-specific risks. Therefore, we examined DLBCL risk in the Transplant Cancer Match Study, including registry-based cancer ascertainment among 96,615 solid organ transplants performed from 2000 to 2008. We determined standardized incidence ratios (SIRs) and 95% confidence intervals comparing DLBCL risk in transplant recipients with that in the general population, and used multivariable Poisson regression models to assess the impact of potential risk factors. We identified 321 incident cases of DLBCL, over 12 times more than expected based on general population rates (SIR = 12.6, 95% confidence interval = 11.2-14.0). SIRs were highest in young recipients and those receiving a lung or pancreas/kidney-pancreas transplant, and were greatly elevated for extranodal DLBCLs at the site of the transplantation compared with other sites. DLBCL risk was highest in the first year following transplantation, and SIRs for early-onset DLBCL risk were elevated in association with Epstein-Barr virus-negative serostatus and use of polyclonal antibody induction therapy. In conclusion, associations between recipient and transplant factors and post-transplantation DLBCL risk suggest a complicated interrelationship among multiple risk factors and timing of disease.

Liver Transplant Pathology: Review of Challenging Diagnostic Situations

Histopathologic assessment of allograft liver biopsies has an important role in managing patients who have undergone liver transplantation. In this review, several topics are discussed that create diagnostic problems in transplant pathology, with emphasis on pathologic features and differential diagnosis. The topics discussed are acute cellular rejection, late acute rejection (centrizonal/parenchymal rejection), chronic rejection, plasma cell hepatitis, idiopathic posttransplant chronic hepatitis, fibrosing cholestatic hepatitis, selected viral infections (cytomegalovirus, Epstein-Barr virus, and hepatitis E), and acute antibody-mediated rejection.

Colocolonic intussusception in a four-yr-old with a heart transplant: a case report and review of the literature

A rare case of a colocolonic intussusception in a pediatric cardiac transplant patient is reported along with a review of colocolonic intussusception in pediatric patients after organ transplantation. A four-yr-old girl with a history of heart transplantation shortly after birth presented with a 12-hour history of abdominal pain, vomiting, and bloody stools. Initial abdominal x-ray showed rectal edema. A rectal examination revealed a palpable intussusceptum that prompted a therapeutic contrast enema, which failed to reduce the intussusception. Surgical exploration was performed with reduction of the intussusception and resection of the terminal ileum and cecum. A pathologic lead point was not identified.

Pre-emptive rituximab based on viraemia and T cell reconstitution: a highly effective strategy for the prevention of Epstein-Barr virus-associated lymphoproliferative disease following stem cell transplantation

This study investigated the efficacy of a pre-emptive strategy based on the combination of Epstein-Barr virus (EBV) viraemia and poor T cell reconstitution in preventing post-transplant lymphoproliferative disease (PTLD) following T cell depleted stem cell transplant (SCT). EBV viral load and immune reconstitution were prospectively monitored in 70 consecutive children undergoing SCT following reduced intensity conditioning with alemtuzumab. Patients who developed significant EBV viraemia (> 40 000 copies/ml blood) were treated pre-emptively with rituximab if they were within 3 months of SCT or their CD3 count was <0·3 × 10⁹ /l. Of 20/70 patients who developed significant EBV viraemia, 13 received pre-emptive rituximab. The incidence of PTLD was significantly reduced in the pre-emptive cohort compared to historical controls (1·4% vs. 21·7%, P = 0·003). This difference was more marked among viraemic patients (2·7% vs. 62·5%P < 0·0001). Patients treated with rituximab demonstrated significantly delayed B cell reconstitution at 1 year post-SCT but this was not associated with an increase in infectious mortality. In 6/6 patients >3 months post-SCT who had a CD3 count >0·3 × 10⁹ /l, reduced immunosuppression only resulted in successful resolution of EBV viraemia without PTLD. This strategy is safe and highly effective in preventing PTLD following T cell depleted SCT, and directs rituximab therapy to patients at highest risk of this complication.

EBV-specific CD8+ T cells from asymptomatic pediatric thoracic transplant patients carrying chronic high EBV loads display contrasting features: activated phenotype and exhausted function

Serial EBV load monitoring of clinically asymptomatic pediatric thoracic organ transplant patients has identified three groups of children who exhibit undetectable (<100 copies/ml), chronic low (100-16,000 copies/ml), or chronic high (>16,000 copies/ml) EBV loads in peripheral blood. Chronic high EBV load patients have a 45% rate of progression to late-onset posttransplant lymphoproliferative disorders. In this article, we report that asymptomatic patients carrying EBV loads (low and high) expressed increased frequencies of EBV-specific CD8(+) T cells, as compared with patients with undetectable EBV loads. Although patients with low viral load displayed EBV-specific CD8(+) T cells with moderate signs of activation (CD38(+/-)/CD127(+/-)), programmed death 1 upregulation and effective IFN-γ secretion, high EBV load carriers showed significant CD38(+) upregulation, features of cellular exhaustion (programmed death 1(+)/CD127(-)) accompanied by a decline in IFN-γ release. Immunopolarization of EBV-specific CD8(+) T cells was skewed from the expected type 1 (IFN-γ) toward type 0 (IFN-γ/IL-5) in patients, and Tr1 (IL-10) in high load carriers. These results indicate the importance of chronic EBV load and of the levels of antigenic pressure in shaping EBV-specific memory CD8(+) T cells. Concomitant phenotypic and functional EBV monitoring is critical for identifying the complex "functional" versus "exhausted" signature of EBV-specific CD8(+) T cells, with implications for immunologic monitoring in the clinic.

Post-transplant lymphoproliferative disorders following solid-organ transplantation

A post-transplant lymphoproliferative disorder (PTLD) is an uncommon but serious complication following solid-organ transplantation. The incidence varies, depending on the type of organ transplanted, the degree of immunosuppression, the number of episodes of acute rejection and a patient's immune status to Epstein-Barr virus. The incidence of PTLD is thought to be bimodal; cases in the first year after solid-organ transplantation are typically related to Epstein-Barr virus. A second incidence occurs more than 1 year following transplantation and is typically not related to Epstein-Barr virus. A variety of therapeutic approaches has been used for these patients, with more recent strategies including the use of rituximab, with or without combination chemotherapy. Efforts continue to be made to improve the outcome of patients with PTLD.

Epitope specificity and clonality of EBV-specific CTLs used to treat posttransplant lymphoproliferative disease

In a recent phase II clinical trial using banked allogeneic CTL lines to treat EBV-associated posttransplant lymphoproliferative disease, a response rate of 52% was recorded 6 mo posttreatment. Tumor response was associated with an increase in both CTL/recipient HLA matches and CD4(+) T cells within the infused CTL lines. The present study was undertaken to correlate tumor response with CTL specificity. The majority of CTL lines infused recognized EBV-encoded nuclear Ag-3 proteins, but CTL protein specificity itself did not correlate with tumor response. Specificity in conjunction with donor/recipient functional HLA matching as opposed to HLA matching alone, however, was important for tumor response. CTL receptor TCR beta-chain variable gene subfamilies were polyclonal, with no preferential use of a particular family. However, tumor response was improved in those receiving CTL lines with polyclonal vs clonal distribution for subfamilies 2, 3, and 9. Interestingly, in five of six tumors (five Hodgkin's-like and one Burkitt's-like posttransplant lymphoproliferative disease) with restricted viral gene expression a complete response was recorded, although in some cases the tumor cells did not express the proteins recognized by the infused CTL. Thus CTL were advantageous when functionally HLA matched but for certain tumor types complete responses occurred in the absence of detectable specific CTL/tumor recognition. We suggest that either the allogenic CTL contained small, undetectable, EBV-specific, HLA-matched T cell populations or perhaps they stimulated nonspecific inflammatory responses in vivo, which were beneficial for tumor regression. These observations should be considered when designing and implementing CTL therapies.

Epstein-Barr virus-associated lymphoproliferative disease after allogeneic haematopoietic stem cell transplantation: molecular monitoring and early treatment of high-risk patients

PURPOSE OF REVIEW

Epstein-Barr virus-associated lymphoproliferative disease (EBV-LPD) is a rare but serious complication in recipients of allogeneic stem cell transplants. An overview is given of the incidence, monitoring and (early) treatment of EBV-LPD.

RECENT FINDINGS

The most important risk factor for EBV-LPD is the use of in-vivo T-cell depletion with antithymocyteglobulin. In addition, alternative donor stem cell transplantation is associated with an increased risk for EBV-LPD. Monitoring of EBV DNA in high-risk patients and subsequent early treatment is very successful, resulting in a low EBV-associated mortality. The monitoring of EBV-specific cytotoxic T lymphocytes might further increase the positive predictive value of EBV DNAemia for EBV-LPD. Once overt EBV-LPD has been diagnosed, rituximab treatment is indicated, guided by monitoring of EBV DNA. The infusion of donor lymphocytes is highly effective, but may be complicated by graft-versus-host disease. Therefore, the infusion of T cells, which have been depleted of alloreactive cells, is currently receiving attention.

SUMMARY

EBV DNA levels should be monitored in patients with high-risk features. Early treatment may be instituted at predefined DNA levels (preemptive approach) or at the earliest signs of LPD (prompt approach). Stepwise treatment guided by EBV DNA, including interruption of immunosuppression, rituximab, and adoptive T-cell immunotherapy may all add to the low mortality currently associated with LPD following allogeneic stem cell transplantation.

Allogeneic hematopoietic stem cell transplantation for Epstein-Barr virus-associated T/natural killer-cell lymphoproliferative disease in Japan

Epstein-Barr virus (EBV)-associated T/NK-cell lymphoproliferative disease (LPD) has been linked to several different disorders. Its prognosis is generally poor and a treatment strategy has yet to be established. There are reports, however, that hematopoietic stem cell transplantation (HSCT) can cure this disease. To clarify the current situation regarding allogeneic hematopoietic stem cell transplantation (allo-HSCT) for EBV-associated T/NK-LPD, a nationwide survey was performed in Japan. Data for 74 patients were collected. There were 42 cases of chronic active EBV infection (CAEBV), 10 cases of EBV-associated hemophagocytic lymphohistiocytosis (EBV-HLH), and 22 cases of EBV-associated lymphoma/leukemia (EBV-lymphoma/leukemia). Of those with CAEBV, 54% had the EBV-infected T-cell type and 59% with EBV-lymphoma/leukemia had the EBV-infected NK-cell type. Most patients with EBV-HLH and EBV-lymphoma/leukemia received allo-HSCT within 1 year after onset compared to only 14% of patients with CAEBV. The event-free survival (EFS) rate following allo-HSCT was 0.561 +/- 0.086 for CAEBV, 0.614 +/- 0.186 for EBV-HLH, and 0.309 +/- 0.107 for EBV-lymphoma/leukemia. The EFS of allo-HSCT with conventional conditioning was 0.488 +/- 0.074 and with reduced-intensity conditioning was 0.563 +/- 0.124. Thus, in a substantial number of cases, EBV-associated T/NK-LPD can be cured by either allogeneic conventional stem cell transplantation or reduced-intensity stem cell transplantation.

CD4 and CD8 T cell responses to tumour-associated Epstein-Barr virus antigens in nasopharyngeal carcinoma patients

Nasopharyngeal carcinoma (NPC), an Epstein-Barr virus (EBV)-associated tumour common in Southern Chinese populations, is a potentially important target for T cell-based immunotherapy. The tumour cells are HLA class I- and II-positive and express a limited subset of EBV latent proteins, namely the nuclear antigen EBNA1 and the latent membrane proteins LMP2 and (in some cases) LMP1. To ask whether the tumour develops in the presence of a potentially protective host response or in its absence, we set out to determine the prevailing levels of CD4+ and CD8+ T cell memory to these proteins in NPC patients at tumour diagnosis. We first screened healthy Chinese donors against Chinese strain EBNA1, LMP1 and LMP2 sequences in Elispot assays of interferon-gamma release and identified the immunodominant CD4+ and CD8+ epitope peptides presented by common Chinese HLA alleles. Then, comparing 60 patients with >70 healthy controls on peptide epitope mini-panels, we found that T cell memory to CD4 epitopes in all three proteins was unimpaired in the blood of patients at diagnosis. In most cases NPC patients also showed detectable responses to CD8 epitopes relevant to their HLA type, the one consistent exception being the absence in patients of a B*4001-restricted response to LMP2. We infer that NPC arises in patients whose prevailing levels of T cell memory to tumour-associated EBV proteins is largely intact; the therapeutic goal must therefore be to re-direct the existing memory repertoire more effectively against antigen-expressing tumour cells.

CNS or bone marrow involvement as risk factors for poor survival in post-transplantation lymphoproliferative disorders in children after solid organ transplantation

PURPOSE

To identify prognostic factors of survival in pediatric post-transplantation lymphoproliferative disorder (PTLD) after solid organ transplantation.

PATIENTS AND METHODS

A multicenter, retrospective case analysis of 55 pediatric solid organ graft recipients (kidney, liver, heart/lung) developing PTLD were reported to the German Pediatric-PTLD registry. Patient charts were analyzed for tumor characteristics (histology, immunophenotypes, cytogenetics, Epstein-Barr virus [EBV] detection), stage, treatment, and outcome. Probability of overall and event-free survival was analyzed in defined subgroups using univariate and Cox regression analyses.

RESULTS

PTLD was diagnosed at a median time of 29 months after organ transplantation, with a significantly shorter lag time in liver (0.83 years) versus heart or renal graft recipients (3.33 and 3.10 years, respectively; P = .001). The 5-year overall and event-free survival was 68% and 59%, respectively, with 59% of patients surviving 10 years. Stage IV disease with bone marrow and/or CNS involvement was associated independently with poor survival (P = .0005). No differences in outcome were observed between early- and late-onset PTLD, monomorphic or polymorphic PTLD, and EBV-positive or EBV-negative PTLD, respectively. Patients with Burkitt or Burkitt-like PTLD and c-myc translocations had short survival (< 1 year).

CONCLUSION

Stage IV disease is an independent risk factor for poor survival in pediatric PTLD patients. Prospective multicenter trials are needed to delineate additional risk factors and to assess treatment approaches for pediatric PTLD.

EBV-related disease following haematopoietic stem cell transplantation with reduced intensity conditioning

The use of reduced intensity regimens has decreased early mortality following stem cell transplantation. However, the increased immunosuppression following these protocols results in profound and often prolonged lymphopenia, resulting in an increased incidence of viral reactivation. We and others have observed a high incidence of EBV viraemia and post-transplant lymphoproliferative disease (PTLD) following reduced-intensity conditioning regimens, reflecting the delayed recovery of EBV-specific immunity after such transplants. The clinical and histological features at presentation are similar to that seen after conventional intensity conditioning. Given the increasing use of reduced intensity conditioning (RIC) transplants, we review the risk factors for EBV related disease following transplantation with RIC, the potential for pre-emptive therapy of PTLD based on monitoring EBV viraemia and management options in such patients.

Allogeneic cytotoxic T-cell therapy for EBV-positive posttransplantation lymphoproliferative disease: results of a phase 2 multicenter clinical trial

We present the results of a multicenter clinical trial using Epstein-Barr virus (EBV)-specific cytotoxic T lymphocytes (CTLs) generated from EBV-seropositive blood donors to treat patients with EBV-positive posttransplantation lymphoproliferative disease (PTLD) on the basis of the best HLA match and specific in vitro cytotoxicity. Thirty-three PTLD patients who had failed on conventional therapy were enrolled. No adverse effects of CTL infusions were observed and the response rate (complete or partial) in 33 patients was 64% at 5 weeks and 52% at 6 months. Fourteen patients achieved a complete remission, 3 showed a partial response, and 16 had no response at 6 months (5 died before completing treatment). At 5 weeks, there was a significant trend toward better responses with higher numbers of CD4(+) cells in infused CTL lines (P = .001) that were maintained at 6 months (P = .001). Patients receiving CTLs with closer HLA matching responded better at 6 months (P = .048). Female patients responded better than male patients, but the differences were not statistically significant. Our results show that allogeneic CTLs are a safe and rapid therapy for PTLD, bypassing the need to grow CTLs for individual patients. The response rate in this poor prognosis patient group is encouraging.

Senile EBV-associated B-cell lymphoproliferative disorder of prepatellar bursa in an elderly patient with multifocal urate arthropathy

We report a case of an EBV-associated high grade B-cell lymphoproliferative disorder occurring in the synovial membrane of an elderly patient with gout arthropathy. The EBV-infected B-cells displayed a pattern of viral gene expression (EBNA2+/LMP1+) typically seen during primary EBV-infection and in lymphoproliferations occurring in immunosuppressed individuals. This case conforms to senile EBV-associated lymphoproliferative disorders previously reported only in Japanese patients. We suggest that an impaired EBV-specific T-cell immunity, local or systemic, may play a role in the development of this disorder and that chronic diseases such as gout may be contributing factors.

Post-transplant lymphoproliferative disorders

Post-transplant lymphoproliferative disorder is the most common malignancy, with the exception of skin cancer, after solid organ transplantation in adults. The incidence varies according to the transplanted organ and is often associated with Epstein-Barr virus. Prognosis is variable, due in part to the heterogeneity of the disease, which ranges from reactive plasmacytic hyperplasia to aggressive monoclonal disease.

Advances in pediatric heart transplantation

PURPOSE OF REVIEW

Heart transplantation has become a reasonable treatment option for pediatric patients with end-stage heart failure or complex congenital cardiac defects not amenable to conventional surgical intervention. This review will summarize the current state of pediatric cardiac transplantation and review recent advances leading to new therapies.

RECENT FINDINGS

Improvements in early mortality after cardiac transplantation have occurred consistently over time since the 1980s, short-term survival rates are high, and most patients enjoy an excellent quality of life with minimal restrictions. The reduction of late mortality is still a major challenge, however, largely as a result of transplant-related coronary artery disease causing chronic graft failure and arrhythmogenic sudden death. Additional causes of morbidity and mortality occurring late after transplantation include renal dysfunction related to chronic immunosuppressive therapy with calcineurin inhibitors (tacrolimus or cyclosporine) and posttransplant lymphoproliferative disorders related to chronic immunosuppression. Newer agents (sirolimus, everolimus) have shown promise in immunosuppressive regimens that may alter the development or progression of long-term complications.

SUMMARY

New immunosuppressive agents allow alterations in drug regimens to minimize renal complications, and may influence the incidence and progression of transplant vasculopathy. Recent studies on posttransplant lymphoproliferative disorders should result in earlier diagnosis and therapy.

A peptide-based inhibitor for prevention of B cell hyperproliferation induced by Epstein–Barr virus

Epstein-Barr virus (EBV) infects and transforms resting B lymphocytes in vitro. The virus can also cause B cell lymphomas in immunosuppressed humans. Indeed, EBV-mediated post-transplant lymphoproliferative disease causes significant complications in transplant recipients, including loss of the transplanted organ and even death. The limited treatment options include, nonspecific targeting of B cell surface antigens with monoclonal antibodies or withdrawal of immunosuppression. These therapies fail in approximately 50% of patients. Clearly, treatments that specifically target EBV-infected cells are desirable. The EBV antigen EBNA3C regulates cell cycle by targeting critical cellular complexes such as cyclin A/cdk2, SCF(Skp2), and Rb. Here, we use a 20-amino-acid EBNA3C-derived peptide, fused to an HIV TAT tag for efficient delivery, to disrupt cell cycle regulation by EBNA3C. The peptide inhibited hyperproliferation of EBV-infected B cell lines and reduced in vitro immortalization of primary B lymphocytes by EBV. Importantly, the peptide inhibited lymphoblastoid outgrowth from the blood of an EBV-positive transplant patient in vitro.

Lymphoproliferative disorders after paediatric heart transplantation: a multi-institutional study

BACKGROUND

Post-transplant lymphoproliferative disorders (PTLD) are an important cause of morbidity and mortality after organ transplantation. We sought to better define the prevalence, pathology, current therapeutic approaches, and outcomes of PTLD in a large group of children who had received heart transplants.

METHODS

We assessed data on patients followed up at 19 centres in the Pediatric Heart Transplant Study (PHTS) from 1993 to 2002. Probability of freedom from PTLD was assessed along with details of presentation, pathology, treatment, and outcomes. Risk factors for survival and event-free survival were investigated.

FINDINGS

Of 1184 primary transplant recipients, 56 (5%) developed PTLD. Probability of freedom from PTLD was 98% at 1 year, 94% at 3 years, and 92% at 5 years. Mean time to PTLD was 23.8 months. Most common sites of disease were gastrointestinal tract (n=22, 39%) and respiratory system (n=14, 25%). Histology was polymorphic in 35 (65%) and monomorphic in 19 (35%). 47 of 48 cases were of B-cell origin, 39 of 45 (87%) were Epstein-Barr virus positive. Probability of survival was 75% at 1 year, 68% at 3 years, and 67% at 5 years after diagnosis. Death from graft loss was as frequent as death from PTLD.

INTERPRETATION

About 5% of paediatric heart-transplant recipients develop PTLD, almost always of B-cell lineage and driven by Epstein-Barr virus. Although many achieve satisfactory outcomes, mortality remains substantial with death due to progressive disease and allograft loss. Advances in management should focus on strategies to protect the allograft as well as improved therapies for PTLD.

Regression of Epstein-Barr virus-induced B-cell transformation in vitro involves virus-specific CD8+ T cells as the principal effectors and a novel CD4+ T-cell reactivity

T-cell memory to Epstein-Barr virus (EBV) was first demonstrated through regression of EBV-induced B-cell transformation to lymphoblastoid cell lines (LCLs) in virus-infected peripheral blood mononuclear cell (PBMC) cultures. Here, using donors with virus-specific T-cell memory to well-defined CD4 and CD8 epitopes, we reexamine recent reports that the effector cells mediating regression are EBV latent antigen-specific CD4+ and not, as previously assumed, CD8+ T cells. In regressing cultures, we find that the reversal of CD23+ B-cell proliferation was always coincident with an expansion of latent epitope-specific CD8+, but not CD4+, T cells; furthermore CD8+ T-cell clones derived from regressing cultures were epitope specific and reproduced regression when cocultivated with EBV-infected autologous B cells. In cultures of CD4-depleted PBMCs, there was less efficient expansion of these epitope-specific CD8+ T cells and correspondingly weaker regression. The data are consistent with an effector role for epitope-specific CD8+ T cells in regression and an auxiliary role for CD4+ T cells in expanding the CD8 response. However, we also occasionally observed late regression in CD8-depleted PBMC cultures, though again without any detectable expansion of preexisting epitope-specific CD4+ T-cell memory. CD4+ T-cell clones derived from such cultures were LCL specific in gamma interferon release assays but did not recognize any known EBV latent cycle protein or derived peptide. A subset of these clones was also cytolytic and could block LCL outgrowth. These novel effectors, whose antigen specificity remains to be determined, may also play a role in limiting virus-induced B-cell proliferation in vitro and in vivo.

Double-step PCR assay to quantify Epstein-Barr viral load in peripheral blood

Posttransplant lymphoproliferative disorders (PTLD) are a severe complication arising in solid organ transplant patients. A strong correlation between Epstein-Barr virus (EBV) infection, the grade and type of immunosuppression, and the development of PTLD has been recognized. This article describes the development of a double-step polymerase chain reaction (PCR) assay for the quantification of EBV-deoxyribonucleic acid (DNA) to monitor EBV infection. Screening of samples containing >/=10(3) viral genomes/10(5) peripheral blood mononuclear cells (PBMC) or 100 micro L serum by a semiquantitative PCR assay is followed by quantification of the samples containing a high number of viral genomes in a quantitative-competitive (QC)-PCR assay. Screening by semiquantitative PCR selects samples with a high number of viral genomes for use in the more labor-intensive and expensive QC-PCR assay and thus provides a handy means for quantitative DNA analysis of large numbers of samples. Our double-step PCR assay can be employed in EBV viral load measurement in PBMC and serum samples to monitor transplanted patients at risk to develop PTLD.

Dual stimulation of Epstein-Barr Virus (EBV)-specific CD4+- and CD8+-T-cell responses by a chimeric antigen construct: potential therapeutic vaccine for EBV-positive nasopharyngeal carcinoma

Virus-associated malignancies are potential targets for immunotherapeutic vaccines aiming to stimulate T-cell responses against viral antigens expressed in tumor cells. Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma, a high-incidence tumor in southern China, expresses a limited set of EBV proteins, including the nuclear antigen EBNA1, an abundant source of HLA class II-restricted CD4(+) T-cell epitopes, and the latent membrane protein LMP2, a source of subdominant CD8(+) T-cell epitopes presented by HLA class I alleles common in the Chinese population. We used appropriately modified gene sequences from a Chinese EBV strain to generate a modified vaccinia virus Ankara recombinant, MVA-EL, expressing the CD4 epitope-rich C-terminal domain of EBNA1 fused to full-length LMP2. The endogenously expressed fusion protein EL is efficiently processed via the HLA class I pathway, and MVA-EL-infected dendritic cells selectively reactivate LMP2-specific CD8(+) memory T-cell responses from immune donors in vitro. Surprisingly, endogenously expressed EL also directly accesses the HLA class II presentation pathway and, unlike endogenously expressed EBNA1 itself, efficiently reactivates CD4(+) memory T-cell responses in vitro. This unscheduled access to the HLA class II pathway is coincident with EL-mediated redirection of the EBNA1 domain from its native nuclear location to dense cytoplasmic patches. Given its immunogenicity to both CD4(+) and CD8(+) T cells, MVA-EL has potential as a therapeutic vaccine in the context of nasopharyngeal carcinoma.

Latent gene sequencing reveals familial relationships among Chinese Epstein-Barr virus strains and evidence for positive selection of A11 epitope changes

Epstein-Barr virus (EBV) strains from the highly HLA-A11-positive Chinese population are predominantly type 1 and show a variety of sequence changes (relative to the contemporary Caucasian prototype strain B95.8) in the nuclear antigen EBNA3B sequences encoding two immunodominant HLA-A11 epitopes, here called IVT and AVF. This has been interpreted by some as evidence of immune selection and by others as random genetic drift. To study epitope variation in a broader genomic context, we sequenced the whole of EBNA3B and parts of the EBNA2, 3A, and 3C genes from each of 31 Chinese EBV isolates. At each locus, type 1 viruses showed <2% nucleotide divergence from the B95.8 prototype while type 2 sequences remained even closer to the contemporary African prototype Ag876. However, type 1 isolates could clearly be divided into families based on linked patterns of sequence divergence from B95.8 across all four EBNA loci. Different patterns of IVT and AVF variation were associated with the different type 1 families, and there was additional epitope diversity within families. When the EBNA3 gene sequences of type 1 Chinese strains were subject to computer-based analysis, particular codons within the A11-epitope-coding region were among the few identified as being under positive or diversifying selection pressure. From these results, and the observation that mutant epitopes are consistently nonimmunogenic in vivo, we conclude that the immune selection hypothesis remains viable and worthy of further investigation.

CT of Posttransplantation Lymphoproliferative Disorder in Pediatric Recipients of Lung Allograft

OBJECTIVE

The purpose of this study was to determine the CT and clinical findings of posttransplantation lymphoproliferative disorder in pediatric lung allograft recipients.

MATERIALS AND METHODS

We reviewed the medical records and CT examinations of 260 lung transplantations in pediatric patients and found 26 recipients who had 29 episodes of histologically proven posttransplantation lymphoproliferative disorder. The clinical and CT features of the disease, the time to diagnosis, and the outcomes were assessed.

RESULTS

The clinical presentation of posttransplantation lymphoproliferative disorder varied from asymptomatic pulmonary nodules (14/29 [48%]) detected on chest CT to specific (organ-related) and nonspecific symptoms (15/29 [52%]). Intrathoracic posttransplantation lymphoproliferative disorder occurred in 20 (69%) of 29 cases and manifested as multiple pulmonary nodules (n = 17), alveolar infiltrates (n = 2), and combined nodules and infiltrates (n = 1). In eight (28%) of 29 cases, there was extraparenchymal disease, including adenopathy, pleural effusion, and esophageal thickening and erosions. Extrathoracic posttransplantation lymphoproliferative disorder occurred in 13 cases and involved the abdomen (n = 10), paranasal sinuses (n = 2), and brain (n = 1). In the abdomen, extranodal disease was more common than nodal disease and presented as bowel wall thickening, focal mass lesions, and splenomegaly. In 18 of 29 episodes of posttransplantation lymphoproliferative disorder, the histologic diagnosis was lymphoma. The median time to diagnosis after transplantation for the 29 episodes of posttransplantation lymphoproliferative disorder was 10 months. Thirteen of the 26 patients died. The median time of survival after the diagnosis of posttransplantation lymphoproliferative disorder was 17 months.

CONCLUSION

Posttransplantation lymphoproliferative disorder in pediatric lung transplant recipients occurs with relatively high frequency in both the chest and abdomen, tends to have lymphomatous features, and results in substantial mortality rates.

Post-transplantation lymphoproliferative disease in heart and heart-lung transplant recipients: 30-year experience at Stanford University

BACKGROUND

Post-transplantation lymphoproliferative disease (PTLD) is an important source of morbidity and mortality in transplant recipients, with a reported incidence of 0.8% to 20%. Risk factors are thought to include immunosuppressive agents and viral infection. This study attempts to evaluate the impact of different immunosuppressive regimens, ganciclovir prophylaxis and other potential risk factors in the development of PTLD.

METHODS

We reviewed the records of 1026 (874 heart, 152 heart-lung) patients who underwent transplantation at Stanford between 1968 and 1997. Of these, 57 heart and 8 heart-lung recipients developed PTLD. During this interval, 4 different immunosuppressive regimens were utilized sequentially. In January 1987, ganciclovir prophylaxis for cytomegalovirus serologic-positive patients was introduced. Other potential risk factors evaluated included age, gender, prior cardiac diagnoses, HLA match, rejection frequency and calcium-channel blockade.

RESULTS

No correlation of development of PTLD was found with different immunosuppression regimens consisting of azathioprine, prednisone, cyclosporine, OKT3 induction, tacrolimus and mycophenolate mofetil. A trend suggesting an influence of ganciclovir on the prevention of PTLD was not statistically significant (p = 0.12). Recipient age and rejection frequency, as well as high-dose cyclosporine immunosuppression, were significantly (p < 0.02) associated with PTLD development. The prevalence of PTLD at 13.3 years was 15%.

CONCLUSIONS

The overall incidence of PTLD was 6.3%. It was not altered by sequential modifications in treatment regimens. Younger recipient age and higher rejection frequency were associated with increased PTLD occurrence. The 15% prevalence of PTLD in 58 long-term survivors was unexpectedly high.

Epstein-Barr virus-recent advances

Epstein-Barr virus is a tumorigenic herpes virus that is ubiquitous in the adult population. The virus is generally spread to and between young children through salivary contact, and only causes clinical illness where primary infection is delayed until adolescence or beyond, when an intense immunopathological reaction leads to the symptoms of infectious mononucleosis in roughly 50% of cases. More than 90% of the world's population carry Epstein-Barr virus as a life-long, latent infection of B lymphocytes. Recent data show that by mimicking B-cell antigen-activation pathways the virus enters the long-lived memory B lymphocyte pool where it evades immune elimination by severely restricting its own gene expression. By influencing B-cell survival mechanisms Epstein-Barr virus may induce tumours such as B lymphoproliferative disease and Hodgkin's disease. Vaccines are being developed to prevent and/or treat these conditions, but an animal model is required to study pathogenesis before a rational vaccine strategy can be formulated.

Immunological aspects of Epstein-Barr virus infection

Epstein-Barr virus (EBV) is a member of ubiquitous gamma herpes viruses, which primarily induces acute infectious mononucleosis (IM) or subclinical infection in susceptible subjects. The host reactions account for the clinical manifestation of IM. This virus also contributes to the development of lymphoid or epithelial malignancies. The outgrowth of EBV-infected B-cells is first controlled by interferon (IFN)-gamma and natural killer (NK) cells, and later by EBV-specific cytotoxic T-lymphocytes (CTL). To overcome the host responses and establish the persistent infection, EBV conducts the protean strategies of immune evasion. Several EBV genes modulate apoptotic signals and cytokine balances to persist B-cell infection without insulting the host. Uncontrolled lymphoproliferation occurs as EBV(+) B-cell lymphoproliferative disease (LPD)/lymphoma in AIDS, posttransplant, or primary immunodeficiency diseases (PID). On the other hand, EBV(+) T/NK cells are involved in EBV-associated hemophagocytic lymphohistiocytosis (EBV-HLH) or chronic active EBV infection (CAEBV) in children having no underlying immunodeficiencies, and at times lead to the clonal evolution of T/NK-cell LPD/lymphomas. Recent advance in molecular techniques has enabled us to analyze the clonality of EBV-infected lymphocytes and to quantify the gene expression of EBV and cytokines. Dominant autocrine loop of T helper (Th) 2 and Th1 may exert in EBV(+) B-LPD and T-LPD, respectively. Intensive studies on the immunological interface between effector components and EBV(+) target cells will provide more information on clarifying the pathogenesis of EBV-associated lymphoid malignancies, as well as on exploiting the therapeutic and preventive strategies for the formidable EBV-associated disease in childhood.

Longitudinal analysis of Epstein-Barr viral load in plasma and peripheral blood mononuclear cells of transplanted patients by real-time polymerase chain reaction

BACKGROUND

Posttransplant lymphoproliferative disease (PTLD) is a significant cause of morbidity and mortality in transplant recipients and is caused by iatrogenic suppression of T cell function. Elevations in the Epstein-Barr viral (EBV) load in plasma (>1000 EBV copies/100 microL plasma) or peripheral blood mononuclear cells (PBMC) (>5000 EBV copies/microg PBMC DNA) as determined by real-time quantitative polymerase chain reaction (RQ-PCR) have been shown to be sensitive indicators for the development of PTLD in patients.

METHODS

The diagnostic value of frequent monitoring of EB viral load in peripheral blood from 46 patients after heart transplantation was investigated compared with 21 healthy controls in a prospective longitudinal study. EB viral load was detected in PBMC and plasma using real-time quantitative (RQ)- polymerase chain reaction (PCR)-based assays and compared with serological parameters of EBV infection or with the occurrence of CMV reactivations.

RESULTS

EB viral load was significantly increased in PBMC and in plasma from transplanted patients compared with healthy controls. Regarding levels and fluctuations of EB viral load in PBMC, patients were grouped in three distinct categories with high, intermediate, or low EB viral load. Although in one patient without PTLD, the EB viral load exceeded the threshold value for PTLD of 5000 EBV copies/microg PBMC DNA, all patients had an EB viral load in plasma of less than 1000 EBV copies/100 microL plasma. No correlation was found between the level of EB viral load and serological parameters of EBV reactivations in patients or in healthy control individuals. EBV and cytomegalovirus reactivations occurred independently in the majority of patients.

CONCLUSIONS

EB viral load measurements in plasma and PBMC of patients using RQ-PCR are superior to serology and are a powerful tool for monitoring transplanted patients.

Inhibition of EBV-induced lymphoproliferation by CD4(+) T cells specific for an MHC class II promiscuous epitope

Posttransplant lymphoproliferative disorder (PTLD) and B cell lymphomas induced by EBV continue to be a major life-threatening complication in transplant patients. The establishment and enhancement of T cell immunity to EBV before transplantation and immunosuppressive therapy could help diminish these complications, but the lack of an effective vaccine has limited this prophylactic approach. We describe here the identification of a peptide epitope from the EBV EBNA2 Ag that is capable of inducing in vitro CD4(+) T cell responses that inhibit the EBV-mediated B lymphocyte proliferation associated with PTLD. Most significantly, T cell responses to the EBNA2 epitope were found to be restricted by numerous MHC class II alleles (DR1, DR7, DR16, DR52, DQ2, and DQ7), indicating that this peptide is highly promiscuous and would be recognized by a large proportion (>50%) of the general population. These results are relevant for the design of a simple, inexpensive and widely applicable peptide-based vaccine to prevent PTLD in solid organ transplant patients.

Treatment of Epstein-Barr-virus-positive post-transplantation lymphoproliferative disease with partly HLA-matched allogeneic cytotoxic T cells

BACKGROUND

Epstein-Barr virus (EBV)-associated post-transplantation lymphoproliferative disease (PTLD) is a common, often fatal, complication of bone-marrow and solid-organ transplantation. Since tumour growth results from inadequate T-cell control of latent EBV, new immunotherapeutic approaches to treatment are being pioneered.

METHODS

In a phase 1/2 trial, eight patients with progressive PTLD unresponsive to conventional treatment were given one to six infusions of partly HLA-matched allogeneic EBV-specific cytotoxic T lymphocytes (CTLs) from a frozen bank of CTLs derived from healthy blood donors.

FINDINGS

Of the five patients who completed treatment, three had complete remission and two had no clinical response. One patient partly responded after two infusions. No graft-versus-host disease or allo-specific antibodies were detected, and graft function improved in three cases. Tumour responses were mainly seen in those with early, localised, polyclonal disease. EBV load in peripheral blood fell to undetectable levels in all patients who responded to treatment, but was more variable in those who did not.

INTERPRETATION

Treatment of EBV-associated PTLD with partly HLA-matched CTLs grown from unrelated donors is effective. Spontaneous remission is very unlikely to account for tumour regression in our patients; however, a larger, controlled trial is needed to assess this treatment further. The frozen bank of allogeneic CTLs is less prohibitively labour intensive and expensive for wide scale use than treatment with autologous CTLs. Such banks could be established to treat other infectious and neoplastic diseases in many patients.

Posttransplant lymphoproliferative disorders in lung transplant patients: the Cleveland Clinic experience

PTLD is a well-recognized complication of organ transplantation. Large series of heart, renal, and liver transplants have been examined for the incidence and behavior of PTLD. However, reports of the incidence and characteristics of PTLDs in lung transplant (LTx) patients are few. We report our experience with PTLDs in a large series of LTx recipients at a single institution and compare them to other solid organ transplant recipient PTLDs seen at our institution. Twenty-eight patients were found to have PTLD, of whom 8 were lung transplant recipients. We evaluated nine PTLD specimens from these 8 patients for their histology, immunophenotype (CD20, CD3, EBV-LMP1), EBER status by in situ hybridization, and clinical features. The incidence of PTLD was 3.3% (8/244 patients). The time to development of PTLD, after transplant, was short (median time, 7 mo). All were of B-cell lineage. Overall, EBV was demonstrated in 77.7% (7 of 9 specimens) of PTLDs. All specimens tested for clonality were found to be monoclonal. Five patients died, with a median time to death of only 4.6 months. PTLDs in LTx patients are EBV-associated B-cell, predominantly monoclonal lymphoid lesions similar to other solid organ transplant PTLDs. Compared with other solid organ transplant recipients with PTLD at our institution, PTLDs in LTx patients have a propensity to involve the transplanted organ (P =.001, Fisher's exact test), occur earlier after transplant (P =.003, Wilcoxon test), and have a shorter survival (P =.002, log rank test). Reasons for this may include the relatively higher level of immunosuppression required in these patients and limited options in decreasing it. Although the incidence is low, careful early monitoring of lung transplantation patients is warranted because of the poor prognosis of patients developing this complication.

Gene mutations in lymphoproliferative disorders of T and NK/T cell phenotypes developing in renal transplant patients

Post-transplantation lymphoproliferative disorder (PT-LPD) is characterized by lymphoid proliferation after organ or bone marrow transplantation. In Western countries, most cases of PT-LPD are B-cell-derived and Epstein-Barr virus-associated, in which alterations of c-myc, p53, and N-ras genes might play a role in disease progression. In Japan, PT-LPD of T- and NK/T-cell types are not uncommon in renal transplant patients. Mutations of p53 (exons 4 through 8), K-ras (exons 1 and 2), c-kit (exons 11 and 17), and beta-catenin genes (exon 3) in 12 cases of these diseases were analyzed by PCR single strand conformation polymorphism and then by direct sequencing. p53 gene mutations were detected in 5 of 5 cases of peripheral T-cell lymphoma, 3 (60%) of 5 cases of adult T-cell leukemia/lymphoma, and 1 of 2 cases of NK/T cell lymphoma. Twenty-five percent of T and NK/T cell lymphomas showed K-ras mutations. Mutations of c-kit and beta-catenin genes were found in 33% of cases. Among a total of 42 substitution mutations, 40 were transitions with involvement of CpG sites in 20 to 30% of cases. Most cases had at least one mutation that changed an amino acid, which might have provided the selection pressure for expansion. These findings suggested that p53 gene mutations might play a central role in development of peripheral T-cell lymphoma including adult T-cell leukemia/lymphoma in renal transplant patients.

Phosphatidylinositol 3-kinase is essential for the proliferation of lymphoblastoid cells

B-cell lymphoma, which is increasing world wide, includes such varied conditions as post-transplant lymphoproliferative disease (PTLD) and Burkitt's lymphoma. This study has characterized a role for the signalling molecule phosphatidylinositol 3-kinase, PI3K, in the regulation of growth and survival of immortalized B-lymphocytes. Burkitt's lymphoma cells die rapidly following inhibition of PI3K with LY294002, a chemical inhibitor. Furthermore, Epstein-Barr virus (EBV) immortalized B-cells, lymphoblastoid cell lines, which are a model of PTLD, do not die but are growth inhibited. This growth inhibition is due to an accumulation at G1 phase of the cell cycle and is paralleled by a loss of E2F transcriptional activity, which is essential for cell cycle entry. An active form of PI3K promotes E2F transcriptional activity in lymphoblastoid cell lines. Treatment of LCL with LY294002 causes a reduction of the expression of both cyclin D2 and cyclin D3, two key cyclins required for cell cycle progression but does not affect the expression of the EBV latent genes, EBNA2A or LMP-1. LY294002 also causes an increase in p27kip1, a cyclin dependent kinase inhibitor and results in the dephosphorylation of members of the pocket protein family. These data describe a mechanism by which PI3K plays a role in B-lymphocyte growth and suggests that a pathway from PI3K to D-type cyclin expression may provide diagnostic or treatment opportunities.

Resistance to Fas-mediated apoptosis in EBV-infected B cell lymphomas is due to defects in the proximal Fas signaling pathway

Post-transplant lymphoproliferative disorder is characterized by the outgrowth of EBV-infected B cell lymphomas in immunosuppressed transplant recipients. Using a panel of EBV-infected spontaneous lymphoblastoid cell lines (SLCL) derived from post-transplant lymphoproliferative disorder patients, we assessed the sensitivity of such lymphomas to Fas-mediated cell death. Treatment with either an agonist anti-Fas mAb or Fas ligand-expressing cells identifies two subsets of SLCL based on their sensitivity or resistance to Fas-driven apoptosis. Fas resistance in these cells cannot be attributed to reduced Fas expression or to mutations in the Fas molecule itself. In addition, all SLCL are sensitive to staurosporine-induced cell death, indicating that there is no global defect in apoptosis. Although all SLCL express comparable levels of Fas signaling molecules including Fas-associated death domain protein, caspase 8, and caspase 3, Fas-resistant SLCL exhibit a block in Fas-signaling before caspase 3 activation. In two SLCL, this block results in impaired assembly of the death-inducing signaling complex, resulting in reduced caspase 8 activation. In a third Fas-resistant SLCL, caspase 3 activation is hindered despite intact death-inducing signaling complex formation and caspase 8 activation. Whereas multiple mechanisms exist by which tumor cells can evade Fas-mediated apoptosis, these studies suggest that the proximal Fas-signaling pathway is impeded in Fas-resistant post-transplant lymphoproliferative disorder-associated EBV(+) B cell lymphomas.

Patients at risk for development of posttransplant lymphoproliferative disorder: plasma versus peripheral blood mononuclear cells as material for quantification of Epstein-Barr viral load by using real-time quantitative polymerase chain reaction

BACKGROUND

Early diagnosis of Epstein-Barr virus (EBV)-associated posttransplant lymphoproliferative disorder (PTLD) is required to detect a stage of disease that is more likely to respond to treatment. Elevated levels of EBV DNA were found in peripheral blood of patients at the onset of PTLD.

METHODS

To compare plasma and peripheral blood mononuclear cells (PBMCs) as material for real-time quantitative polymerase chain reaction (RQ-PCR) measurement of Epstein-Barr viral load, we used two sets of primers and probes specific for the BAM HI-K or BAM HI-W region of the EBV genome.

RESULTS

Patients with PTLD had a median viral load of 19,200 EBV genomes/microg DNA (n=9) or 3,225 EBV genomes/100 microl plasma (n=5), being significantly higher compared with immunosuppressed patients with primary (n=9) or reactivated (n=20) EBV infection or immunosuppressed patients without serological signs of active EBV infection (n=67) (P<0.001). Hence, a value of greater than 5,000 EBV genomes/microg PBMC DNA was considered as a diagnostic parameter for PTLD with a sensitivity and specificity of 1.00 or 0.89, respectively. When plasma was analyzed, however, a value of greater than 1,000 EBV genomes/100 microl plasma had both a sensitivity and specificity of 1.00 for the diagnosis of PTLD. During remission of PTLD, viral load was more effectively cleared in plasma compared with PBMCs. In plasma of nonimmunosuppressed individuals, even a qualitative detection of EBV-related sequences was sensitive and specific for the diagnosis of primary EBV infection, whereas for analysis of PBMC DNA a quantitative parameter had to be considered to differentiate healthy individuals (< 100 EBV genomes/microg PBMC DNA) from patients with primary EBV infection (>100 EBV genomes/microg PBMC DNA).

CONCLUSION

Although both PBMCs and plasma were useful as material for EBV-specific RQ-PCR in immunosuppressed patients and nonimmunosuppressed individuals, the specificity of analysis seemed to be higher if plasma was taken for analysis.

Epstein-Barr virus-associated T-cell lymphoma in solid organ transplant recipients

Post-transplantation lymphoproliferative diseases (PTLDs) are a heterogenous group of lymphoid proliferative disorders occurring in transplant patients. Most PTLDs are B-cell in origin; T-cell PTLDs are seldom reported, and EBV-associated T-cell PTLDs are rare. The first case of a T-cell, non-EBV-associated PTLD was first described in a renal allograft recipient in 1987. A total of 40 cases of T-cell PTLDs in solid organ transplant recipients have been reported. However, so far only 16 cases of EBV-associated T-cell PTLDs have been reported in the literature. The sites of occurrence of EBV-associated T-cell PTLDs were in the gastrointestinal tract, lungs, bone marrow, skin, liver and spleen. The pathogenesis of EBV-associated T-cell PTLD is uncertain; it is speculated that the EBV may infect a subset of T-cells that express the CD21 receptor. The present treatment of EBV-associated T-cell PTLD consists of surgical removal, reduction or withdrawal of immunosuppression and/or radiotherapy and chemotherapy. The prognosis is uncertain, and the 1-year survival for patients who were followed up for 1 year was 50%.

Epstein-Barr virus-specific T cells for the management of Epstein-Barr virus lymphomas

Epstein-Barr virus (EBV), a human herpes virus, is associated with a variety of malignancies. In vitro, it is able to transform B cells, which will grow as lymphoblastoid cell lines in the absence of T cells. Patients with a variety of immunodeficiency diseases are subject to the development of B-cell lymphomas that express viral antigens on their cell surface. Development of EBV-associated B-cell lymphomas is seen in solid organ transplant and bone marrow transplant recipients receiving immunosuppressive therapy. Transfer of mature T cells from EBV-immune marrow donors has been demonstrated to be effective in controlling these EBV-associated B-cell tumors. Recently the demonstration that EBV transcripts are found in other lymphomas (including Hodgkin disease cells) has led to the suggestion that transfer of EBV-specific T cells may also be effective in managing these tumors. Current research involves optimizing methods to expand cells that recognize the EBV antigens expressed in the lymphoma cells.