Increased incidence of EBV-associated lymphoproliferative disorders after allogeneic stem cell transplantation from matched unrelated donors due to a change of T cell depletion technique

Role of Viral Infections in the Pathogenesis of Sjögren's Syndrome: Different Characteristics of Epstein-Barr Virus and HTLV-1

Viruses are possible pathogenic agents in several autoimmune diseases. Sjögren’s syndrome (SS), which involves exocrine dysfunction and the appearance of autoantibodies, shows salivary gland- and lacrimal gland-oriented clinical features. Epstein-Barr virus (EBV) is the most investigated pathogen as a candidate that directly induces the phenotype found in SS. The reactivation of the virus with various stimuli induced a dysregulated form of EBV that has the potential to infect SS-specific B cells and plasma cells that are closely associated with the function of an ectopic lymphoid structure that contains a germinal center (GC) in the salivary glands of individuals with SS. The involvement of human T-cell leukemia virus type 1 (HTLV-1) in SS has been epidemiologically established, but the disease concept of HTLV-1-associated SS remains unexplained due to limited evidence from basic research. Unlike the cell-to-cell contact between lymphocytes, biofilm-like structures are candidates as the mode of HTLV-1 infection of salivary gland epithelial cells (SGECs). HTLV-1 can infect SGECs with enhanced levels of inflammatory cytokines and chemokines that are secreted from SGECs. Regardless of the different targets that viruses have with respect to affinitive lymphocytes, viruses are involved in the formation of pathological alterations with immunological modifications in SS.

The value of EBV DNA in early detection of post-transplant lymphoproliferative disorders among solid organ and hematopoietic stem cell transplant recipients

PURPOSE

Emerging EBV DNAemia in plasma is considered an early sign of post-transplant lymphoproliferative disorder (PTLD). The aim of this study was to quantify the extent of benefit from screening for EBV DNAemia to detect emerging PTLD among solid organ (SOT) or hematopoietic stem cell transplant recipients (HSCT).

METHODS

We used receiver operating characteristic (ROC) curves for assessing ability of models to predict PTLD. Among 2642 recipients transplanted between January 2004 and December 2014, 79 (3%) developed PTLD.

RESULTS

EBV DNAemia was observed in 331/1784 recipients (18.6%, 95% CI 16.8-20.4) with measured EBV DNA. The area under the curve (AUC) of the ROC of EBV DNAemia to identify persons with subsequent PTLD was 72% (95% CI, 64-79%) among SOT and 59% (51-68%) among HSCT. Including clinical predictors such as age, gender, transplant year and type, high-risk EBV serostatus, and routine biochemistry in addition to EBV DNAemia increased AUC to 83% (75-90%) among SOT and 84% (79-89%) among HSCT. Among HSCT, including additional factors such as T-cell-depleting treatment, acute graft vs. host disease and donor match increased AUC to 85% (78-91%).

CONCLUSIONS

We constructed a model to better predict PTLD compared to EBV DNA screening alone which could have clinical implications.

Epstein-barr virus DNAemia monitoring for the management of post-transplant lymphoproliferative disorder

BACKGROUND

Post-transplant lymphoproliferative disorder (PTLD) is a potentially fatal complication of allogeneic hematopoietic cell transplantation (HCT). Epstein-Barr virus (EBV) reactivation (detectable DNAemia) predisposes to the development of PTLD.

METHODS

We retrospectively studied 306 patients monitored for EBV DNAemia after Thymoglobulin-conditioned HCT to determine the utility of the monitoring in the management of PTLD. DNAemia was monitored weekly for ≥12 weeks post-transplantation.

RESULTS

Reactivation was detected in 82% of patients. PTLD occurred in 14% of the total patients (17% of patients with reactivation). PTLD was treated with rituximab only when and if the diagnosis was established. This allowed us to evaluate potential DNAemia thresholds for pre-emptive therapy. We suggest 100,000-500,000 IU per mL whole blood as this would result in unnecessary rituximab administration to only 4-20% of patients and near zero mortality due to PTLD. After starting rituximab (for diagnosed PTLD), sustained regression of PTLD occurred in 25/25 (100%) patients in whom DNAemia became undetectable. PTLD progressed or relapsed in 12/17 (71%) patients in whom DNAemia was persistently detectable.

DISCUSSION

In conclusion, for pre-emptive therapy of PTLD, we suggest threshold DNAemia of 100,000-500,000 IU/mL. Persistently detectable DNAemia after PTLD treatment with rituximab appears to have 71% positive predictive value and 100% negative predictive value for PTLD progression/relapse.

Epstein-Barr Virus-associated Lymphoproliferative Disorder with Encephalitis Following Anti-thymocyte Globulin for Aplastic Anemia Resolved with Rituximab Therapy: A Case Report and Literature Review

Epstein-Barr virus (EBV)-associated lymphoproliferative disorders (LPDs) sometimes occur following Anti-thymocyte globulin (ATG) administration for allogenic stem cell transplantation but are rare in aplastic anemia (AA) patients. A 55-year-old woman with AA following ATG developed refractory fever and was diagnosed with EBV-LPD. She was successfully treated with weekly rituximab monotherapy; however, she developed EBV encephalitis. She was admitted to the intensive care unit and finally recovered from unconsciousness. EBV-LPD should be considered after ATG for AA when symptoms appear. Because EBV-LPD following ATG for AA can rapidly progress, weekly monitoring of EBV-DNA and early intervention may be necessary.

Use of lectins in immunohematology

Lectins are carbohydrate binding proteins present in seeds of many plants, especially corals and beans, in fungi and bacteria, and in animals. Apart from their hemagglutinating property, a wide range of functions have been attributed to them. Their importance in the area of immunohematology is immense. They are used to detect specific red cell antigens, to activate different types of lymphocytes, in order to resolve problems related to polyagglutination and so on. The introduction of advanced biotechnological tools generates new opportunities to exploit the properties of lectins, which were not used earlier. Stem cell research is a very important area in transplant medicine. Certain lectins detect surface markers of stem cell. Hence, they are used to understand the developmental biology of stem cells. The role of various lectins in the areas of transfusion and transplant medicine is discussed in detail in this review.

In vivo effects of horse and rabbit antithymocyte globulin in patients with severe aplastic anemia

We recently reported that rabbit antithymocyte globulin was markedly inferior to horse antithymocyte globulin as a primary treatment for severe aplastic anemia. Here we expand on our findings in this unique cohort of patients. Rabbit antithymocyte globulin was detectable in plasma for longer periods than horse antithymocyte globulin; rabbit antithymocyte globulin in plasma retained functional capacity to bind to lymphocytes for up to 1 month, horse antithymocyte globulin for only about 2 weeks. In the first week after treatment there were much lower numbers of neutrophils in patients treated with rabbit antithymocyte globulin than in patients receiving horse antithymocyte globulin. Both antithymocyte globulins induced a "cytokine storm" in the first 2 days after administration. Compared with horse antithymocyte globulin, rabbit antithymocyte globulin was associated with higher levels of chemokine (C-C motif) ligand 4 during the first 3 weeks. Besides a much lower absolute number and a lower relative frequency of CD4(+) T cells, rabbit antithymocyte globulin induced higher frequencies of CD4(+)CD38(+), CD3(+)CD4(-)CD8(-) T cells, and B cells than did horse antithymocyte globulin. Serum sickness occurred around 2 weeks after infusion of both types of antithymocyte globulin. Human anti-antithymocyte globulin antibodies, especially of the IgM subtype, correlated with serum sickness, which appeared concurrently with clearance of antithymocyte globulin in blood and with the production of cytokines. In conclusion, rabbit and horse antithymocyte globulins have very different pharmacokinetics and effects on neutrophils, lymphocyte subsets, and cytokine release. These differences may be related to their efficacy in suppressing the immune system and restoring hematopoiesis in bone marrow failure. Clinicaltrials.gov identifier: NCT00260689.

Successful rescue of early graft failure in pediatric patients using T-cell-depleted haploidentical hematopoietic SCT

Graft failure (GF) is a significant complication after allogeneic hematopoietic stem cell transplantation (HCT) and is associated with a high mortality rate. We performed re-transplantation using haploidentical-related donors to rescue children with early GF. Between 2008 and 2013, 10 patients received re-transplantation from haploidentical family donors. The median age at HCT was 13.5 years and the median time between transplantations was 52.5 days. Conditioning regimen with fludarabine and CY was used in seven patients, and TBI was added in three patients. All 10 patients received T-cell-depleted grafts using CD3 or CD3/CD19 MoAb. The median numbers of CD34(+) and CD3(+) cells were 5.52 × 10(6)/kg and 1.08 × 10(6)/kg, respectively. For GVHD prophylaxis, mycophenolate mofetil (MMF) and tacrolimus or MMF and CYA were used. All 10 patients achieved a sustained neutrophil engraftment and maintained a complete donor chimerism at the time of analysis (median 23 months, range 6-62 months). Nine of 10 patients were alive, and one patient with moyamoya disease with AML died of encephalopathy 7 months post transplant. This study suggests that fludarabine- and CY-based conditioning with T-cell-depleted haploidentical HCT is a feasible option to rescue pediatric patients with primary GF.

Haploidentical stem cell transplantation

The feasibility of stem cell transplantation across the major histocompatibility barrier-as in haploidentical stem cell transplantation-has been proved for some time in several studies. The main limitations include a higher graft failure rate, delayed immune reconstitution after transplantation with high rates of life-threatening infections, a higher incidence of post-transplant lymphoproliferative disease, and severe acute and chronic graft-versus-host disease. In an attempt to reduce the transplant-related morbidity/mortality, several techniques had been evaluated involving conditioning regimen intensity, graft engineering, post-transplant cellular therapy and immunosuppression. This review will describe the current situation. It will also discuss initiatives and strategies to overcome the limitations associated with transplant across the MHC barrier.

Strategies to prevent EBV reactivation and posttransplant lymphoproliferative disorders (PTLD) after allogeneic stem cell transplantation in high-risk patients

Epstein-Barr virus (EBV)-associated postallogeneic stem cell transplantation (SCT) lymphoproliferative disorder (PTLD) is often life threatening. The risk of EBV reactivation is highest in older patients, T cell-depleted SCT (in vivo or vitro), and in unrelated or mismatched SCT. Cumulative numbers of patients with EBV reactivation and PTLD are rising as more patients at high risk for EBV reactivation and PTLD are receiving allo-SCT. Novel but easily applicable strategies are needed to prevent EBV reactivation and PTLD to serve the needs of the increasingly enlarging population of high-risk SCT recipients across the globe.

High incidence of post transplant lymphoproliferative disorder after antithymocyte globulin-based conditioning and ineffective prediction by day 28 EBV-specific T lymphocyte counts

The largest study on post-allogeneic hematopoietic cell transplant lymphoproliferative disorder (PTLD) epidemiology showed a cumulative incidence of 1.7% in patients receiving antithymocyte globulin (ATG). We had noted an apparently higher incidence in our transplant recipients whose conditioning included ATG. Therefore, we formally determined the incidence of PTLD through chart review. We also evaluated whether counts of EBV-specific T lymphocytes measured by cytokine flow cytometry could identify patients at risk of developing PTLD. Among 307 allogeneic transplant recipients, 25 (8.1%) developed PTLD. This was biopsy proven in 11 patients, and was fatal in seven patients. Patient age, EBV serostatus, donor type/match or GVHD did not influence PTLD risk significantly. Median onset of PTLD was 55 (range, 28-770) days post transplant. Day 28 EBV-specific T lymphocyte counts were not significantly different in 11 patients who developed PTLD and 31 non-PTLD patients matched for published risk factors for PTLD. In summary, when using conditioning with thymoglobulin 4.5 mg/kg, the incidence of PTLD is relatively high and cannot be predicted by day 28 cytokine flow cytometry-determined EBV-specific T lymphocyte counts. Thus, in this scenario PTLD prevention may be warranted, for example, using EBV DNAemia monitoring with preemptive therapy.

Evaluation of T- and NK-cell-targeted therapies: is there a role for rituximab prophylaxis?

Splizimomab, an antibody that targets CD2, was studied in the treatment of T and natural killer cell lymphoma and was found to be associated with Epstein-Barr virus lymphoproliferative disease. B cell depletion may provide a platform for further evaluation of this and other promising antibody approaches that result in T cell depletion.

Current status of haploidentical stem cell transplantation for leukemia

Haploidentical hematopoietic stem cell transplantation has made tremendous progress over the past 20 years and has become a feasible option for leukemia patients without a HLA identical sibling donor. The early complications of severe graft-versus-host disease (GVHD), graft failure and delayed engraftment, as well as disease recurrence have limited the use of this approach. Newer strategies have been applied and overcome some of the problems, including the use of T-cell depleted graft, "mega" dose of stem cells, intensive post-transplant immunosuppression and manipulation of the graft. These have decreased the transplant related mortality and GVHD associated with haploidentical transplantation, however, the major problems of disease relapse and infection, which related to late immune reconstitution, limit the development of haploidentical HSCT. Future challenges remain in improving post-transplant immune reconstitution and finding the best approach to reduce the incidence and severity of GVHD, while preserving graft-versus-leukemia effect to prevent the recurrence of underlying malignancy.

Haploidentical haematopoietic stem cell transplantation for acute leukaemia in adults: experience in Europe and the United States

Work on one haplotype-mismatched transplants has been proceeding for over 20 years all over the world and novel transplant techniques have been developed. Some centres have focused on the conditioning regimens and post transplant immune suppression; others have concentrated on manipulating the graft. Haploidentical transplant modalities are based mainly on high-intensity conditioning regimen, but reduced intensity regimens have recently been introduced. The graft may be a megadose of extensively T cell-depleted or unmanipulated progenitor cells. Excellent engraftment rates are associated with a very low incidence of GVHD- and regimen-related mortality even in patients who are over 50 years old. Overall, event-free survival and transplant-related mortality compare favourably with reports on transplants from sources of stem cells other than the matched sibling. Improvements will come with successful implementation of strategies to accelerate and strengthen post transplant immune reconstitution as well as transplantation of patients in early stage disease.

The haploidentical option for high-risk haematological malignancies

Much progress has been made in the clinical, biological and technical aspects of the T-cell-depleted full-haplotype mismatched transplants for acute leukaemia. Our experience demonstrates that infusing a megadose of extensively T-cell-depleted haematopoietic peripheral blood stem cells after an immuno-myeloablative conditioning regimen in acute leukaemia patients ensures sustained engraftment with minimal GvHD without the need of any post-transplant immunosuppressive treatment. Since our first successful pilot study, our efforts have concentrated on developing new conditioning regimens, optimising the graft processing and improving the post-transplant immunological recovery. The results we have so far achieved in more than 200 high-risk acute leukaemia patients show that haploidentical transplantation is now a clinical reality. Because virtually all patients have a mismatched family member, who is immediately available, mismatched transplantation should be offered as a viable option to high-risk acute leukaemia patients who do not have, or cannot find, a matched donor.

Reconstitution of lymphocyte subpopulations in children with inherited metabolic storage diseases after haematopoietic cell transplantation

We prospectively evaluated the reconstitution of lymphocyte subpopulations in nine children with lysosomal diseases who underwent 11 allogeneic haematopoietic cell transplants (HCTs) following CD34(+) immunomagnetic enrichment, limited T-cell addback and in vivo B-cell depletion. Absolute lymphocyte count recovery was slow to cross the 5th percentile, occurring at a median of 10 months after HCT in patients with full chimaerism. Natural killer cells represented up to 90% of the total lymphoid population during the first 3 months. CD4(+) lymphocyte recovery occurred 9-18 months after HCT. In most patients, CD8(+) lymphocyte recovery was slow and comparable with that of CD4(+) lymphocytes. The CD4(+)/CD8(+) ratio normalised by 3-7 months after HCT in 50% of the patients. CD8(+) lymphocyte recovery was enhanced in patients with viral reactivation. Reconstitution of B-lymphocytes was particularly delayed in patients treated with rituximab. Declining chimaerism, rejection and viral reactivation were the most common problems in our series. Because of the unique graft manipulation, the pace of lymphocyte reconstitution was particularly slow, suggesting that these patients are at a significantly increased risk of infections for up to 2 years after HCT.

Increased incidence of EBV-related disease following paediatric stem cell transplantation with reduced-intensity conditioning

The incidence of Epstein-Barr virus (EBV) viraemia and lymphoproliferative disease (LPD) was studied in a consecutive cohort of 128 paediatric patients undergoing stem cell transplantation (SCT) with reduced-intensity conditioning (RIC; n = 65) or conventional-intensity conditioning (CIC; n = 68). Following CIC, six of 68 (8%) developed viraemia; all remained asymptomatic. EBV viraemia (23 of 65 patients = 35%, P < 0.001) and LPD (10 of 65 = 15%, P < 0.001) were significantly more frequent following RIC. Of the 23 RIC patients who developed viraemia, eight remained asymptomatic, five had symptomatic viraemia (fever +/- rash), and 10 patients developed LPD, two of whom died. An absolute lymphocyte count of <0.3 x 10(9)/l at the time of onset of viraemia was strongly predictive of development of LPD (P < 0.05) in this group. The incidence of viraemia was significantly higher in patients receiving serotherapy with antithymocyte globulin (ATG; 15 of 43, 35%) than Campath (12 of 73, 16.4%, P < 0.05). Primary immunodeficiency and acute graft-versus-host disease were associated with EBV viraemia in univariate analysis, but were not independent risk factors. In conclusion, EBV viraemia and LPD appear to be significantly more common in children following RIC SCT, particularly with selective depletion of recipient T cells relative to B cells following the use of ATG. This probably reflects the profound immunosuppression following RIC SCT, together with the incomplete ablation of recipient-derived B cells.

An unexpectedly high incidence of Epstein-Barr virus lymphoproliferative disease after CD34+ selected autologous peripheral blood stem cell transplant in neuroblastoma

The risk of Epstein–Barr virus lymphoproliferative disease (EBV-LPD) increases with the use of highly immunosuppressive therapies. Allogeneic BMT, especially supported by T-cell-depleted stem cell products, is a risk factor for EBV-LPD. Although the risk of EBV-LPD after autologous transplantation is low, case reports of this complication in the autologous setting exist. We report a higher incidence than previously described of EBV-LPD in children undergoing sequential high-dose chemotherapy supported with CD34 selected peripheral blood stem cells (CD34+ PBSC). The median time to LPD after tandem transplant was 3 months (range 1–5 months). Five patients out of 156 (3.5%) developed EBV-LPD while enrolled on two trials of tandem autologous SCT in high-risk pediatric malignancies. Both studies employed five cycles of induction therapy, followed by tandem autologous PBSC transplants. In all, 108 out of 156 patients received CD34+ PBSC; 48 received unselected PBSC. All patients contracting LPD were from the CD34 selected group. Treatment of EBV-LPD included rituximab in four out of five patients, IVIg in two out of five patients, and gancyclovir in two out of five patients. EBV-LPD resolved in four out of five patients. We conclude that the combination of tandem SCT and CD34 selection may have increased immunosuppression in these patients to a point where there is an elevated risk of EBV-LPD.

Risk factors for the development of post-transplant lymphoproliferative disorder in a large animal model

A high incidence of a post-transplant lymphoproliferative disorder (PTLD) is observed in miniature swine conditioned for allogeneic hematopoietic cell transplantation using a protocol involving T-cell depletion and cyclosporine therapy. This study was designed to assess contributing factors to disease development. Forty-six animals were studied including 12 (26%) that developed PTLD. A number of risk factors for PTLD were examined, including degree of immunosuppression, degree of MHC mismatch and infection by a porcine lymphotrophic herpesvirus (PLHV-1). Flow cytometry was used to measure host and donor T- and B-cell levels in the peripheral blood. Porcine lymphotrophic herpesvirus viral load was determined by quantitative PCR. Animals developing PTLD had significantly lower levels of T cells on the day of transplant. Cyclosporine levels did not differ significantly between animals with and without PTLD. Animals receiving transplants across a two-haplotype mismatch barrier showed an increased incidence of PTLD. All animals with PTLD had significant increases in PLHV-1 viral loads. Porcine lymphotrophic herpesvirus viral copy numbers remained at low levels in the absence of disease. The availability of a preclinical large-animal model with similarities to PTLD of humans may allow studies of the pathogenesis and treatment of that disorder.

Sequence analysis of EBV DNA isolated from mouth washings and PBMCs of healthy individuals and blood of EBV-LPD patients

BACKGROUND

Lymphoproliferative disorder (LPD) caused by Epstein-Barr virus (EBV) is a severe complication of bone marrow transplantation. The EBV strain causing LPD is of either donor or recipient origin, however, available data are limited to only a small number of cases. To obtain solid evidence, comparison of the EBV strain that caused the EBV-LPD with pre-stem cell transplantation (SCT) EBV strains of donor and recipient is imperative. Available techniques rely on the production of EBV transformed lymphoblastoid cell lines and lack sensitivity.

OBJECTIVE

The aim of this study was to develop a simple method for EBV sequence analysis on mouth washings (MWs) and peripheral blood mononuclear cells (PBMCs).

STUDY DESIGN

EBV DNA was extracted from MWs and PBMCs that were collected from 20 healthy individuals. DNA was used for sequence analysis, using a polymerase chain reaction for the C-terminus of the LMP-1 gene.

RESULTS

In seropositive individuals EBV DNA could be detected in 11/14 (79%) MWs and in 13/14 (93%) PBMC samples. Sequence analysis showed that in 11 out of 14 (79%) healthy individuals sequence patterns could be established. In these 11 healthy individuals 13 sequence patterns could be detected. Eleven of these 13 patterns (84.6%) were unique. These results encouraged us to explore the feasibility of this method on EBV DNA isolated from plasma from 9 EBV-LPD patients at time of EBV reactivation. In 7 EBV-LPD patients 8 sequence patterns were detected. Six out of 8 sequence patterns (75%) were unique.

CONCLUSION

Our method is suitable for strain identification and we intend to use this technique to evaluate EBV origin in EBV-LPD patients.

Megadose transplantation of highly purified haploidentical stem cells: current results and future prospects

The transplantation of megadoses of haploidentical hematopoietic stem cells is for a number of children with malignant or nonmalignant diseases the only curative approach. In order to prevent severe GvHD, the removal of T lymphocytes from the stem cell graft either by positive selection of CD34+ stem cells or by negative depletion of CD3+ T lymphocytes is necessary. We present the results obtained so far by CD34+ positive selection and discuss new techniques of graft engineering which might hopefully further improve the outcome of haploidentical stem cell transplantation.

Differential diagnosis of skin lesions after allogeneic haematopoietic stem cell transplantation

Allogeneic haematopoietic stem cell transplantation (i.e. bone marrow or peripheral blood stem cell transplantation) is a common procedure in the treatment of various haematological disorders such as aplastic anaemia, (pre)leukaemias, some malignant lymphomas, multiple myeloma and immunodeficiency states. Many of these patients develop erythematous skin lesions following transplantation. Although graft- versus-host disease is the major differential diagnosis in these situations, many other causes of erythema are encountered. The large number of transplant patients means that more and more pathologists are confronted with the challenging problem of making a correct diagnosis in these situations. In this review article we therefore describe the different causes of erythema and their differential diagnoses. In most cases the clinical presentation is related to the microscopical features. Besides acute and chronic graft-versus-host disease, we discuss the (common) drug reactions and non-specific features such as Sweet's syndrome, erythema nodosum and eosinophilic folliculitis. In addition, we deal with the recurrence of original diseases and infections. With this knowledge every pathologist should feel comfortable when looking at skin biopsies of patients after haematological stem cell transplantation.

Influence of cytomegalovirus seropositivity on outcome after T cell-depleted bone marrow transplantation: contrasting results between recipients of grafts from related and unrelated donors

We analyzed the effect of cytomegalovirus (CMV) serostatus on overall survival (OS) and transplant-related mortality (TRM) in 253 consecutively treated patients receiving partially T cell-depleted (TCD) bone marrow from either matched related donors (MRDs; n=205) or matched unrelated donors (MUDs; n=48). Short-course, low-dose preemptive therapy with ganciclovir was provided as soon as a positive antigenemia assay result was obtained. Ganciclovir prophylaxis, which was identical to preemptive therapy, was given to patients with acute graft-versus-host disease (GVHD) grades II-IV who had to be treated with high-dose steroids. In recipients of transplants from MRDs, inferior OS and increased TRM were predicted by extensive chronic GVHD (P<.001). High-risk disease status and older age adversely influenced OS (P=.001) and TRM (P=.002), respectively; older age resulted in a trend toward decreased OS (P=.066). In recipients of transplants from MUDs, OS and TRM were strongly influenced by patient CMV seropositivity (P=.013 and.007, respectively). In conclusion, CMV seropositivity is not an adverse risk factor for OS and TRM in recipients of transplants from MRDs. However, in recipients of transplants from MUDs, patient CMV seropositivity strongly affects OS and TRM.