Interferon-alpha affects the immune response in post-transplant lymphoproliferative disorder

Identification of multiple potent neutralizing and non-neutralizing antibodies against Epstein-Barr virus gp350 protein with potential for clinical application and as reagents for mapping immunodominant epitopes

Prevention of Epstein-Barr virus (EBV) infection has focused on generating neutralizing antibodies (nAbs) targeting the major envelope glycoprotein gp350/220 (gp350). In this study, we generated 23 hybridomas producing gp350-specific antibodies. We compared the candidate gp350-specific antibodies to the well-characterized nAb 72A1 by: (1) testing their ability to detect gp350 using enzyme-linked immunosorbent assay, flow cytometry, and immunoblot; (2) sequencing their heavy and light chain complementarity-determining regions (CDRs); (3) measuring the ability of each monoclonal antibody (mAb) to neutralize EBV infection in vitro; and (4) mapping the gp350 amino acids bound by the mAbs using competitive cell and linear peptide binding assays. We performed sequence analysis to identify 15 mAbs with CDR regions unique from those of murine 72A1 (m72A1). We observed antigen binding competition between biotinylated m72A1, serially diluted unlabeled gp350 nAbs (HB1, HB5, HB11, HB20), and our recently humanized 72A1, but not gp350 non-nAb (HB17) or anti-KSHV gH/gL antibody.

The management of posttransplant lymphoproliferative disorder

Posttransplant lymphoproliferative disorder (PTLD) is a life-threatening complication of allogeneic hematopoietic stem cell and solid organ transplantation. Most cases are EBV-positive B-cell neoplasms, which occur in the setting of pharmacologically impaired cellular immunity. Several different treatment strategies including cytotoxic antitumor therapy, anti-B-cell monoclonal antibody therapy, antiviral therapy, and modalities aimed at restoration of EBV-specific cellular immunity have been employed. In addition, efforts to identify patients at high risk for PTLD have resulted in attempts at prophylactic and preemptive therapies. In this review we discuss the available literature on differing approaches to PTLD management, identify areas in need of further investigation, and, when possible, make general recommendations. Reduction of immunosuppression remains the mainstay of first-line treatment. Accumulating evidence supports the role of rituximab as second-line therapy with cytotoxic chemotherapy reserved for specific circumstances. Further investigations are needed to better define the role of more novel and less widely available therapies such as the adoptive transfer of EBV-specific T cells and optimization of antiviral therapies.

Post-transplant lymphoproliferative disorder

Post-transplant lymphoproliferative disorder (PTLD) is an increasingly recognized complication of solid organ and hematopoietic stem cell transplantation. PTLD represents a spectrum of polyclonal and monoclonal lymphoproliferation, generally of B cells. Prompt diagnosis is key and requires a high index of suspicion. An increasing variety of highly effective therapies, including immune modulation via reduction in immunosuppression, monoclonal antibodies, and cellular therapy, have dramatically improved the cure rates of this once devastating disease.

Post-Transplant Lymphoproliferative Disorders

Post-transplant lymphoproliferative disorder (PTLD) is a life-threatening complication after hematopoietic stem cell or solid organ transplantation. The majority of PTLD is of B-cell origin and associated with Epstein-Barr virus (EBV). During the past decade progress has been made in better understanding the pathogenesis of PTLD, and early detection strategies, such as serial measurement of EBV-DNA load in peripheral blood samples, have assisted in the identification of high-risk patients. In addition, novel immunotherapies have been developed, including the use of monoclonal antibodies and adoptive transfer of EBV-specific T cells. Despite these advances, it remains a major challenge to define indications for preemptive therapies for PTLD and to integrate novel therapeutic approaches with conventional therapies.

Endobronchial post-transplant lymphoproliferative disorder and its management with photodynamic therapy: a case report

Post-transplant lymphoproliferative disorder (PTLD) is a recognized complication of solid-organ transplantation. We describe a 56-year-old man with end-stage idiopathic pulmonary fibrosis who underwent right-sided single-lung transplantation and who had biopsy-proven PTLD involving the main bronchi 3 months later. The lesions recurred despite endobronchial electrosurgery and systemic therapy with interferon for 3 months. Interferon was deceased and anti-CD20 therapy and photodynamic therapy were performed concurrently using flexible bronchoscopy. The subsequent follow-up endobronchial biopsy specimen results were negative for PTLD. This case is the first reported use of photodynamic therapy combined with anti-CD20 for treating PTLD. Endobronchial PTLD is a rare complication of lung transplantation and can be managed successfully with photodynamic therapy.

Post-transplant lymphoproliferative disorder: a review

Post-transplant lymphoproliferative disorder (PTLD) represents a spectrum of Epstein-Barr virus-related (EBV) clinical diseases, from a benign mononucleosis-like illness to a fulminant non-Hodgkin's lymphoma. In the setting of hematopoietic stem cell transplantation, PTLD is an often-fatal complication occurring relatively early after transplant. Risk factors for the development of PTLD are well established, and include HLA-mismatching, T-cell depletion, and the use of antilymphocyte antibodies as conditioning or treatment of graft-versus-host disease. Early recognition of PTLD is particularly important in the SCT setting, because PTLD in these patients tends to be rapidly progressive. Familiarity with the clinical features of PTLD and a heightened level of suspicion are critical for making the diagnosis. Surveillance techniques with EBV antibody titers and/or polymerase chain reaction (PCR) may have a role in some high-risk settings. Immune-based therapies such as monoclonal anti-B-cell antibodies, interferon-alpha, and EBV-specific donor T cells, either as treatment for PTLD or as prophylaxis in high-risk patients, represent promising new directions in the treatment of this disease.

Diagnosis and management of posttransplant lymphoproliferative disorder in solid-organ transplant recipients

The Epstein-Barr virus (EBV) has a pivotal pathophysiologic role in the development of most lymphoproliferative disorders that occur after solid-organ transplantation. The term "EBV-associated posttransplant lymphoproliferative disorder" (PTLD) includes all clinical syndromes of EBV-associated lymphoproliferation, ranging from uncomplicated posttransplant infectious mononucleosis to true malignancies that contain clonal chromosomal abnormalities. PTLDs are historically associated with a high mortality rate in patients who have a monoclonal form of the disorder. Recently described approaches to pathology, diagnosis, treatment, and preventive strategies of PTLD, however, have the potential to improve outcome.

Interferon and cytotoxic chemotherapy for the treatment of post-transplant lymphoproliferative disorder

Interferon-alpha and cytotoxic chemotherapy may be effective treatment modalities for the post-transplant lymphoproliferative disorder. Interferon-alpha may result in a complete response in up to 40% of patients, while chemotherapy may be effective in 75% of those failing local surgical excision, a reduction in immunosuppression, and an antiviral agent. Interferon may be used early after diagnosis in patients with relatively slowly growing tumors. Chemotherapy should be selected for patients with bulky, rapidly growing malignancies. The toxicity of chemotherapy may be minimized by discontinuing maintenance immunosuppression during chemotherapy, administering GCSF, and providing antimicrobial prophylaxis. Rejection is minimized by the reintroduction of maintenance immunosuppression when the patient is no longer neutropenic.

Anti-CD20 monoclonal antibody therapy in Epstein-Barr Virus-associated B cell lymphoma following lung transplantation

Post-transplant lymphoproliferative disease is a complication of bone marrow and solid organ transplantation, mostly associated with Epstein-Barr virus infection and chronic immunosuppression. Even if spontaneous resolution after cessation of immunosuppressive therapy can be observed, the prognosis of this disorder is usually poor with a low response to specific treatment. We describe a case of B-cell lymphoma of the nasopharynx occurring 6 months after double-lung transplantation. In spite of its monoclonal nature, anti-CD 20 monoclonal antibody given in the presence of reduced immunosuppression resulted in a complete response. The patient also received "consolidation" radiation therapy to prevent the recurrence. The treatment was well tolerated with minimal side effects. The patient was asymptomatic and had a well functioning graft more than 1 year after therapy.

The management of Epstein-Barr virus associated post-transplant lymphoproliferative disorders in pediatric solid-organ transplant recipients

Despite a growing understanding of the pathogenesis and spectrum of Epstein-Barr virus (EBV) and EBV-associated post-transplant lymphoproliferative disease (PTLD) in organ transplant recipients, the optimal management of this complication remains controversial. The absence of comparative data evaluating potential therapeutic strategies explains the lack of uniformly accepted guidelines for the management of PTLD. The purpose of this review is to provide an overview of potential therapies and offer a set of guidelines for the management of EBV-associated PTLD in children.

Cytokine mRNA profiles in Epstein-Barr virus-associated post-transplant lymphoproliferative disorders

Cytokine mRNA patterns were analyzed in 11 post-transplant lymphoproliferative disorder (PTLD) specimens using qualitative reverse-transcriptase polymerase chain reaction (RT-PCR). In each case, a pattern of IL2-, IFN gamma-, IL4+, IL10+ was seen. A similar pattern was observed in a spleen sample from 1 patient with contemporaneous PTLD elsewhere. Semiquantitative RT-PCR for cytokine message was performed using RNA from bronchoalveolar lavage (BAL) specimens obtained from 2 patients with pulmonary PTLD. In both cases, IL4 message predominated. Reduction of message coincided with resolution of the tumors. The pattern differed from that seen in 1 patient with acute pulmonary rejection, in which RT-PCR of BAL cells showed predominance of IL6 and IFN gamma. We conclude that at least some PTLDs exist within a T-helper cell type 2 (Th2)-like cytokine microenvironment. The presence of a similar mRNA pattern in an extratumoral specimen at the time of PTLD suggests that it may reflect a systemic phenomenon. Disappearance of this pattern following PTLD resolution indicates its dynamic nature and is consistent with the hypothesis that specific cytokines contribute to the development of PTLDs.

Interferon-alpha and its effects on post-transplant lymphoproliferative disorders

EBV-transformation induces B lymphocytes to secrete high levels of human IL-10. Additionally, EBV contains a gene, BCRF1, that encodes for a protein that shares activity with human IL-10 in vitro. Thus, infection by EBV seems to promote a Th2 environment in the infected host. One may even hypothesize that EBV-derived IL-10 initiates a cascade of events that promotes a Th2 response and suppresses Th1 activity. This is further confirmed by data that suggest elevated concentrations of IL-4, IL-10, and IgE in patients with PTLD. This implies an association between PTLD and an imbalance in the immunoregulatory system with either an excess suppression of Th1 cells and/or an up-regulation of Th2 cells. One could speculate that if the imbalance in the immunoregulatory system is corrected, the patient's own immune system could potentially defend itself against the virus. Clearly, this is the case in those immunocompromised patients with PTLD who respond to just a reduction in their immunosuppression. Unfortunately, this is only beneficial in approximately half of patients with PTLD. Perhaps this is because patients often do not become entirely immunocompetent, either because all of their immunosuppression cannot be discontinued for fear of rejection or because once the above cascade is established the immune system is not capable of easily switching to the Th1 response necessary for combating the virus. Theoretically, IFN-alpha, because of its anti-viral effect, its anti-neoplastic effect and/or possibly by its ability to promote a Th1 response, should be useful in the treatment of PTLD. IFN-alpha modulates the immune system by several mechanisms including: preventing B cells from producing immunoglobulins, reducing IL-6 receptor density, and augmenting the inhibition of IL-4 by IL-12. In vitro studies document its effectiveness against EBV. Unfortunately, the available evidence as to its efficacy in vivo in patients with PTLD is very limited. At present, there are only 16 reported cases in the literature. There are also three cases of BLPD in immunocompromised patients that were all successfully treated with IFN-alpha and the two cases alluded to earlier from Children's Hospital of Pittsburgh (personal communication). Although the numbers are small, the results are promising. Of the 21 patients with BLPD who received IFN-alpha, 15 achieved complete remission. Four others improved and 2 died from BLPD. One of the 4 that improved died 3 months later from a relapse. Thus, there was an overall mortality of 14% (3 of 21) in those who received therapy with IFN-alpha. This is a very heterogeneous group of patients, several of whom had also received additional therapies. Thus, it is impossible to draw definitive conclusions. However, the mortality rate in this group of patients, who had already failed therapy with a reduction in their immunosuppression, compares very favorably to the reported mortality rate of approximately 23-81% in patients with PTLD. This data suggest that a large multi-centered prospective trial comparing IFN-alpha with and without IVIg to other treatment options (i.e., LAK cells) is warranted in those patients with EBV-positive PTLD who fail to respond to a reduction in their immunosuppression.

Effects of immunotherapy on experimental immunodeficiency-related lymphoproliferative disease

BACKGROUND

Human lymphokine-activated cells (LAK cells) and interferon alpha (IFN-alpha) have been used clinically in the therapy of posttransplant lymphoproliferative disease (PTLD). However, the efficacy of such therapy has not been extensively tested under controlled experimental conditions.

METHODS

A B-cell line, derived from PTLD tissue and clonally related to the parent lesion, was tested for its response to IFN-alpha in vitro. The effects of LAK cells and IFN-alpha therapy were examined in a severe combined immunodeficiency disease (SCID) mouse model in vivo.

RESULTS

The PTLD cell line studied showed a 30% decrease in the rate of growth upon incubation with 500 U/ml of IFN-alpha. This in vitro response was also reproduced in vivo, in tumor therapy studies conducted in SCID mice. The magnitude of this inhibitory effect in vivo was a function of tumor burden and dose of IFN-alpha. In parallel experiments, LAK cells reduced the tumorigenicity of a lymphoblastoid cell line derived from the peripheral blood of a patient with PTLD, and prolonged the survival of SCID-beige mice with established lymphoproliferative disease. In contrast with two prior studies, in which the use of autologous cytotoxic T cells was found to be necessary, we found the administration of third-party non-HLA-matched LAK cells also to be effective in reducing tumor burden.

CONCLUSIONS

These observations demonstrate the efficacy of immunotherapy for lymphoproliferative disease under controlled experimental conditions, and validate currently ongoing efforts exploring the utility of such therapy in the clinical setting.

ICAM-1, soluble-CD23, and interleukin-10 concentrations in serum in renal-transplant recipients with Epstein-Barr virus reactivation

Primary and reactivated Epstein-Barr virus (EBV) infections after organ transplantation are associated with the development of posttransplant lymphoproliferative malignancies. Since viral reactivation frequently stays asymptomatic, early diagnosis and treatment are challenges during posttransplant patient monitoring. Both soluble-CD23 (sCD23) and intercellular adhesion molecule 1 (ICAM-1) cell surface expression as well as interleukin-10 (IL-10) production are closely associated with viral gene expression. Therefore, immunoglobulin M (IgM), IgG, IgA, sCD23, ICAM-1, and IL-10 concentrations were measured in serum samples from patients during EBV reactivation (n = 14) and were compared with those in samples from patients without EBV reactivation (n = 10) following renal transplantation. In addition, serum sCD23, ICAM-1, and IL-10 concentrations were measured longitudinally in weekly to biweekly samples from 10 patients with EBV reactivation for at least 20 weeks following transplantation. A significant elevation of sCD23 was found during viral reactivation (P < 0.05), whereas ICAM-1 levels showed a nonsignificant increase. The finding of a highly significant elevation of the serum IL-10 concentration during EBV reactivation (P < 0.001) may support speculations about its role in EBV-induced lymphoproliferation and in the development of opportunistic infections and secondary malignancies. Maximum serum IL-10 levels at the time of EBV reactivation were found in 7 of 10 patients. Well-defined ICAM-1 and sCD23 concentration peaks were found in 9 of 10 and 8 of 10 patients, respectively. Although both markers are not specific for EBV reactivation and therefore may not be useful for primary diagnosis, sCD23 and ICAM-1 might be potent tools for the clinical monitoring of EBV activity and virus-induced lymphoproliferation.