Post-transplant lymphoproliferative disease (PTLD): lymphokine production and PTLD

Hemophagocytic lymphohistiocytosis is a sign of poor outcome in pediatric Epstein-Barr virus-associated post-transplant lymphoproliferative disease after allogeneic hematopoietic stem cell transplantation

EBV-related PTLD developing after HSCT is a potentially life-threatening disease. HLH is uncommon after allogeneic HSCT. Data on outcome of patients with PTLD and concomitant HLH after allogeneic HSCT are limited. In this retrospective study, we collected demographic, clinical, laboratory, and outcome data for 408 patients who underwent allogeneic HSCT from 2006 to 2015. Graft source included CB (n = 135; 33.1%), PBSCs (n = 34; 8.3%), and BM (n = 239; 58.6%). Eight out of 408 patients (2%) developed EBV-PTLD with a median age at HSCT of 5.9 years (range: 2.3-17.3). All eight patients received ATG as part of the conditioning regimen. Graft source was PBSC in three patients (37.5%), BM in four patients (50%), and CB in one patient (12.5%). Donors were matched unrelated in five patients (62.5%) and matched sibling in three patients (37.5%). Seven out of eight patients developed EBV-PTLD within the first 100-day post-HSCT. Lymph node biopsy revealed early lesions in three patients, polymorphic in three patients, and monomorphic PTLD in two patients. Three patients (37.5%) died within 1 month of EBV-PTLD diagnosis. All deceased patients developed HLH manifestations with two of them meeting HLH diagnostic criteria and one having an incomplete workup. PTLD after allogeneic HSCT with manifestations of HLH is associated with high mortality. Early identification and treatment of EBV-PTLD seems imperative to control the disease, especially if signs of HLH are evolving.

Ceppellini Lecture 2012: collateral damage from HLA mismatching in kidney transplantation

Inclusion of human leukocyte antigen (HLA) matching in donor kidney allocation schemes has been based solely on its association with graft survival. Other long-term effects associated with HLA incompatibility are largely unexplored. Data from deceased donor kidney transplants reported to the Collaborative Transplant Study have been analyzed to assess the relation between HLA mismatching and clinical events to 3 years post-transplant, and an overview of these analyses is presented. A significant correlation was observed between the number of mismatches and the need for anti-rejection therapy during the first year post-transplant, which was maintained for HLA-DR and HLA-A + B mismatching separately and at years 2 and 3 post-transplant. The number of HLA-DR mismatches and the number of HLA-A + B mismatches as well as rejection treatment showed significant associations with the dose of maintenance steroids. The cumulative incidences of death with a functioning graft from infection or cardiovascular causes, but not from cancer, were also significantly associated with HLA mismatching. The number of HLA-DR mismatches showed a significant association with the incidence of non-Hodgkin lymphoma and hip fractures. These findings show that the adverse consequences of HLA mismatching on kidney transplants extend beyond an effect on graft survival, and include an increased risk of death with a functioning graft, non-Hodgkin lymphoma and hip fracture.

Significance of Epstein-Barr virus (EBV) load and Interleukin-10 in post-transplant lymphoproliferative disorders

The complex relationship between EBV, IL-10 and lymphomagenesis has been widely investigated and several studies have highlighted the diagnostic value of EBV DNA copies and serum IL-10, that may be considered as tumor markers. Notwithstanding the great number of data published in the last few years on the behavior of EBV DNA copies in the peripheral blood of transplanted patients, a threshold value significant for impending or overt post-transplant lymphoproliferative disorder (PTLD) has not yet been defined. Too many factors, both technical and clinicopathological, may affect the results of clinical studies, making their comparison difficult. On the contrary, although the role of IL-10 in PTLDs has been well documented, a sufficient number of studies exploring sensitivity and specificity of serum IL-10 measurement is lacking. The aim of this review is to summarise data on EBV load quantification and serum IL-10 detection in transplanted patients, providing clinicians with wide and useful information in order to improve bedside management of transplanted patients with regard to PTLDs occurrence and treatment.

Long-term follow-up of kidney transplant patients with posttransplant lymphoproliferative disorder: duration of posttransplant lymphoproliferative disorder-induced operational graft tolerance, interleukin-18 course, and results of retransplantation

BACKGROUND

Posttransplant lymphoproliferative disorder (PTLD) can be resolved in many transplant patients by the reduction or cessation of immunosuppression, after which many grafts continue to function as the result of a form of operational tolerance. When graft function deteriorates, retransplantation may be an option. Cytokines such as interleukin (IL)-10 and IL-18 may play a role in PTLD tolerance induction and tumor regression. We report long-term follow-up on the duration of graft tolerance and the course of retransplantation in a series of patients who underwent kidney transplantation and demonstrated PTLD, and in whom we were able to perform IL-18 analyses.

RESULTS

Patients were followed for up to 7 years after PTLD diagnosis. Treatment consisted of immunosuppression cessation with radiation therapy in cases with overt monomorphic lymphomas. All patients' PTLDs were resolved, and all patients but one (whose graft was removed) demonstrated a period of operational graft tolerance of up to 5 years. Five patients underwent retransplantation without sign of recurrence of the PTLD up to 3 years after transplantation. In the eight patients analyzed, IL-18 increased significantly during PTLD regression and follow-up in those with long-term operational tolerance.

CONCLUSION

We report on a series of patients with resolved PTLDs demonstrating long-term recurrence-free survival, of whom most experienced a long period of operational graft tolerance. IL-18 seems to play a role in the resolution of the PTLDs. Five patients underwent retransplantation with standard immunosuppression without recurrence. A previous diagnosis of PTLD should not be regarded as a contraindication for later retransplantation.

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.

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.

Signalling events regulating lymphoid growth and survival

Epstein-Barr virus (EBV) uses many different strategies to induce lymphocyte proliferation and survival. In the different states of EBV infection and latency, several genes play specific roles in the induction of cell growth and cell survival proteins. EBNA2A, EBNA-LP and EBNA3C all modulate early events in the G1 phase of the cell cycle. Furthermore, interleukin-6 and interleukin-10, which are induced following EBV infection, appear to be important for growth. They activate signalling pathways that have been shown to link directly to proliferation. Latent membrane protein 1 (LMP1) induces a number of anti-apoptotic proteins via NF- kappa B, and LMP2A also appears to contribute to lymphocyte survival. This paper describes some of the many cellular pathways modulated by EBV that interact with the signalling machinery and thus make lymphocytes survive and grow.

Epstein-Barr virus (EBV) reactivation is a frequent event after allogeneic stem cell transplantation (SCT) and quantitatively predicts EBV-lymphoproliferative disease following T-cell--depleted SCT

Reactivation of the Epstein-Barr virus (EBV) after allogeneic stem cell transplantation (allo-SCT) may evoke a protective cellular immune response or may be complicated by the development of EBV-lymphoproliferative disease (EBV-LPD). So far, very little is known about the incidence, recurrence, and sequelae of EBV reactivation following allo-SCT. EBV reactivation was retrospectively monitored in 85 EBV-seropositive recipients of a T-cell--depleted (TCD) allo-SCT and 65 EBV-seropositive recipients of an unmanipulated allo-SCT. Viral reactivation (more than 50 EBV genome equivalents [gEq]/mL) was monitored frequently by quantitative real-time plasma polymerase chain reaction until day 180 after SCT. Probabilities of developing viral reactivation were high after both unmanipulated and TCD-allogeneic SCT (31% +/- 6% versus 65% +/- 7%, respectively). A high CD34(+) cell number of the graft appeared as a novel significant predictor (P =.001) for EBV reactivation. Recurrent reactivation was observed more frequently in recipients of a TCD graft, and EBV-LPD occurred only after TCD-SCT. High-risk status, TCD, and use of antithymocyte globulin were predictive for developing EBV-LPD. Plasma EBV DNA quantitatively predicted EBV-LPD. The positive and negative predictive values of a viral load of 1000 gEq/mL were, respectively, 39% and 100% after TCD. Treatment-related mortality did not differ significantly between TCD and non-TCD transplants, but the incidence of chronic graft-versus-host disease was significantly less in TCD patients. It is concluded that EBV reactivation occurs frequently after TCD and unmanipulated allo-SCT, especially in recipients of grafts with high CD34(+) cell counts. EBV-LPD, however, occurred only after TCD, and EBV load quantitatively predicted EBV-LPD in recipients of a TCD graft. (Blood. 2001;98:972-978)

An Epstein-Barr virus that expresses only the first 231 LMP1 amino acids efficiently initiates primary B-lymphocyte growth transformation

An Epstein-Barr virus (EBV) recombinant (MS231) that expresses the first 231 amino acids (aa) of LMP1 and is truncated 155 aa before the carboxyl terminus transformed resting B lymphocytes into lymphoblastoid cell lines (LCLs) only when the infected cells were grown on fibroblast feeder cells (K. M. Kaye et al., J. Virol. 69:675-683, 1995). Higher-titer MS231 virus has now been compared to wild-type (WT) EBV recombinants for the ability to cause resting primary B-lymphocyte transformation. Unexpectedly, MS231 is as potent as WT EBV recombinants in causing infected B lymphocytes to proliferate in culture for up to 5 weeks. When more than one transforming event is initiated in a microwell, the MS231 recombinant supports efficient long-term LCL outgrowth and fibroblast feeder cells are not required. However, with limited virus input, MS231-infected cells differed in their growth from WT virus-infected cells as early as 6 weeks after infection. In contrast to WT virus-infected cells, most MS231-infected cells could not be grown into long-term LCLs. Thus, the LMP1 amino-terminal 231 aa are sufficient for initial growth transformation but the carboxyl-terminal 155 aa are necessary for efficient long-term outgrowth. Despite the absence of the carboxyl-terminal 155 aa, MS231- and WT-transformed LCLs are similar in latent EBV gene expression, in ICAM-1 and CD23 expression, and in NF-kappaB and c-jun N-terminal kinase activation. MS231 recombinant-infected LCLs, however, require 16- to 64-fold higher cell density than WT-infected LCLs for regrowth after limiting dilution. These data indicate that the LMP1 carboxyl-terminal 155 aa are important for growth at lower cell density and appear to reduce dependence on paracrine growth factors.

Involvement of Interleukin-10 (IL-10) and Viral IL-6 in the Spontaneous Growth of Kaposi’s Sarcoma Herpesvirus-Associated Infected Primary Effusion Lymphoma Cells

Primary effusion lymphoma (PEL) is a distinct type of lymphoma associated with Kaposi’s sarcoma-associated herpesvirus (KSHV) infection. To determine the factors responsible for the unrestrained proliferation of PEL, we have studied the growth factor requirements of the PEL-derived BCBL-1 and BC-1 cell lines. Both cell lines were found to be autocrine growth factor dependent and to release human interleukin-6 (IL-6), viral IL-6 (vIL-6), and human IL-10 in the culture supernatant. To establish whether these cytokines contribute to autocrine growth, neutralizing antibodies against human IL-6, vIL-6, human IL-10, and soluble IL-10 receptor were used. These experiments showed that human IL-10 and, to a lesser degree, vIL-6 serve as autocrine growth factors for BCBL-1 and BC-1 cells. Thus, human IL-10 and vIL-6 are growth factors released and used by PEL cells for autonomous proliferation and may be critical to the development and progression of PEL.

Involvement of Interleukin-10 (IL-10) and Viral IL-6 in the Spontaneous Growth of Kaposi’s Sarcoma Herpesvirus-Associated Infected Primary Effusion Lymphoma Cells

Primary effusion lymphoma (PEL) is a distinct type of lymphoma associated with Kaposi’s sarcoma-associated herpesvirus (KSHV) infection. To determine the factors responsible for the unrestrained proliferation of PEL, we have studied the growth factor requirements of the PEL-derived BCBL-1 and BC-1 cell lines. Both cell lines were found to be autocrine growth factor dependent and to release human interleukin-6 (IL-6), viral IL-6 (vIL-6), and human IL-10 in the culture supernatant. To establish whether these cytokines contribute to autocrine growth, neutralizing antibodies against human IL-6, vIL-6, human IL-10, and soluble IL-10 receptor were used. These experiments showed that human IL-10 and, to a lesser degree, vIL-6 serve as autocrine growth factors for BCBL-1 and BC-1 cells. Thus, human IL-10 and vIL-6 are growth factors released and used by PEL cells for autonomous proliferation and may be critical to the development and progression of PEL.