Haploidentical hematopoietic stem cell transplantation for lymphoma with monosomy of chromosome 6 (loss of heterozygosity in the HLA region) - Who should be a donor?

Hematopoietic stem cell transplantation (HSCT) from an HLA haploidentical family donor is an option for patients who do not have a full HLA matched donor and lack the time to find an unrelated one.  Furthermore, it may facilitate a powerful graft versus leukemia/lymphoma (GVL) effect to help combat hematological malignancies by directly targeting the mismatched HLA expressed on leukemia/lymphoma cells. [3] On the contrary, leukemia/lymphoma cells escape from the surveillance of the donor-derived GVL effect by losing the target HLA (mismatched HLA in GVH direction). This mechanism has been called loss of heterozygosity (LOH) in the HLA gene region on chromosome 6. Taking  the above into account, in this case report, we present a case of lymphoma with monosomy 6, which means natural LOH of HLA, and suggest that selection of a haploidentical family donor matched with the missing HLA haplotype seems to be very effective (read more)

Concurrent Acute Cellular Rejection Is an Independent Risk Factor for Renal Allograft Failure in Patients With C4d-Positive Antibody-Mediated Rejection

Background: Identification of risk factors for renal allograft failure after an episode of acute antibody-mediated rejection (AMR) may help the outcome of this difficult-to-treat complication.
Methods: During December 2003 to February 2011, 833 kidney graft recipients underwent 1120 clinically indicated biopsies at our center. We reviewed the biopsy results and identified 87 biopsy specimens from 87 patients positive for the degradation product of complement component 4 (C4d) and acute AMR. We generated Kaplan-Meier survival curves and performed a multivariable analysis using the Cox proportional hazards regression model to identify risk factors for allograft failure after C4d+ acute AMR.
Results: Among the 87 patients, 26 had a diagnosis of acute AMR according to the Banff ’09 classification schema, 29 had acute AMR and chronic active AMR, 18 had acute AMR and acute T-cell mediated rejection (TCMR), and 14 had acute AMR, chronic active AMR, and acute TCMR. Kaplan-Meier survival estimates showed that concurrent acute TCMR (P=0.001, Mantel-Cox log-rank test), concurrent chronic active AMR (P=0.03), and time to biopsy (P=0.04) are associated with graft survival. The Cox proportional hazards regression analysis identified that concurrent acute TCMR (hazard ratio, 2.59 [95% confidence interval, 1.21–5.55]; P=0.01) and estimated glomerular filtration rate (hazard ratio, 0.65 [95% confidence interval, 0.48–0.88]; P=0.01) are independent risk factors for allograft loss. Concurrent chronic active AMR or time to biopsy was not associated with graft failure by the multivariable Cox analysis.
Conclusions: Our single-center study has elucidated that concurrent acute TCMR in kidney transplant recipients with C4d+ acute AMR is an independent risk factor for graft failure. Level of allograft function at the time of diagnosis was also an independent predictor of graft loss (read more).

Long-Term Tolerance to Kidney Allografts After Induced Rejection of Donor Hematopoietic Chimerism in a Preclinical Canine Model

Background: Allogeneic hematopoietic cell transplantation provides a reliable method for inducing tolerance toward solid organ grafts. However, this procedure can result in graft-versus-host disease, thereby limiting its application. Here, we test the hypothesis that mixed chimerism can be intentionally reverted to host hematopoiesis without rejection of a kidney graft.
Methods: Recipient dogs were given 2-Gy total-body irradiation (TBI) before and a short course of immunosuppression after marrow infusion from dog leukocyte antigen–identical littermates. All dogs achieved stable mixed chimerism. After a mean of 20 weeks, one cohort of dogs received kidney transplants from their respective marrow donors. Subsequently, recipients were reconditioned with 2-Gy TBI and given autologous granulocyte colony-stimulating factor–mobilized leukocytes (recipient leukocyte infusion [RLI]) that had been collected before marrow transplantation.
Results: Dogs receiving a second TBI and RLI without a kidney transplant rejected their donor hematopoietic graft within 3 weeks. Dogs that received kidney grafts, followed by a second TBI and RLI, rejected their marrow graft without rejecting their transplanted kidneys for periods greater than 1 year.
Conclusion: Mixed chimerism may be clinically reverted to 100% recipient without rejection of a kidney allograft. This finding may have application toward minimizing the risk of graft-versus-host disease in solid organ transplantation patients given hematopoietic cell transplantation from human leukocyte antigen–identical donors (read more).

A Peripheral Blood Diagnostic Test for Acute Rejection in Renal Transplantation

Monitoring of renal graft status through peripheral blood (PB) rather than invasive biopsy is important as it will lessen the risk of infection and other stresses, while reducing the costs of rejection diagnosis. Blood gene biomarker panels were discovered by microarrays at a single center and subsequently validated and cross-validated by QPCR in the NIH SNSO1 randomized study from 12 US pediatric transplant programs. A total of 367 unique human PB samples, each paired with a graft biopsy for centralized, blinded phenotype classification, were analyzed (115 acute rejection (AR), 180 stable and 72 other causes of graft injury). Of the differentially expressed genes by microarray, Q-PCR analysis of a five gene-set (DUSP1, PBEF1, PSEN1, MAPK9 and NKTR) classified AR with high accuracy. A logistic regression model was built on independent training-set (n = 47) and validated on independent test-set (n = 198)samples, discriminating AR from STA with 91% sensitivity and 94% specificity and AR from all other non-AR phenotypes with 91% sensitivity and 90% specificity. The 5-gene set can diagnose AR potentially avoiding the need for invasive renal biopsy. These data support the conduct of a prospective study to validate the clinical predictive utility of this diagnostic tool (read more).

Everolimus is associated with a reduced incidence of cytomegalovirus infection following de novo cardiac transplantation

Background : Cytomegalovirus (CMV) causes several complications following cardiac transplantation including cardiac allograft vasculopathy. Previous studies suggested that immunosuppressive treatment based on everolimus might reduce CMV infection. Aiming to better characterize the action of everolimus on CMV and its interplay with patient/recipient serology and anti-CMV prophylaxis, we analyzed data from 3 large randomized studies comparing various everolimus regimens with azathioprine (AZA)- and mycophenolate mofetil (MMF)-based regimens.
Methods : CMV data were analyzed from 1009 patients in 3 trials of de novo cardiac transplant recipients who were randomized to everolimus 1.5 mg/day, everolimus 3 mg/day, or AZA 1–3 mg/kg/day, plus standard-dose (SD) cyclosporine (CsA; study B253, n = 634); everolimus 1.5 mg/day plus SD- or reduced-dose (RD)-CsA (study A2403, n = 199); and everolimus 1.5 mg/day plus RD-CsA or MMF plus SD-CsA (study A2411, n = 176).
Results : In study B253, patients allocated to everolimus experienced almost a 70% reduction in odds of experiencing CMV infection compared with AZA (P < 0.001). In study A2403, CMV infection was low in both everolimus arms, irrespective of CsA dosing, and in study A2411, patients allocated to everolimus experienced an 80% reduction in odds of experiencing CMV infection, compared with MMF (P < 0.001). CMV syndrome/disease was rare and less frequent in everolimus-treated patients. Subgroup analyses showed that the benefit everolimus provides, in terms of CMV events, is retained in CMV-naïve recipients and is independent of anti-CMV prophylaxis or preemptive approaches.
Conclusions : Everolimus is associated with a lower incidence of CMV infection compared with AZA and MMF, which combined with its immunosuppressive efficacy and antiproliferative effects may positively impact long-term outcomes (read more).

Enrichment of Regulatory T Cells in Acutely Rejected Human Liver Allografts

Acute cellular rejection (ACR) occurs frequently after liver transplantation and can usually be controlled. Triggering of allospecific immune responses and lack of immunoregulation are currently suggested as a cause of ACR, but there are no investigations of intrahepatic immune responses during ACR. Therefore we prospectively analyzed the intrahepatic T cell infiltration pattern in correlation to the severity of ACR in a cohort of patients with graft hepatitis (n = 151). While CD4⁺ cells dominated the portal infiltrates in mild–moderate ACR, CD8⁺ cells prevailed in severe ACR. Furthermore portal CD8⁺ and not CD4⁺ infiltration correlated with serum transaminases and with the likelihood of subsequent ACRs. Surprisingly, the rise of portal effector T cells density during ACR was surpassed by the increase in portal infiltration of regulatory T cells by a factor of two. Thus ACRs rather showed an increase and not a lack of regulation, as was suggested by analysis of peripheral blood mononuclear cells. Despite the pattern of enhanced immunoregulation, patients with severe ACR had a higher risk for subsequent rejections and showed a trend to a reduced survival. Thus, patients with severe rejections might need a modification of their immunosuppression to improve prognosis (read more).

HIV and HLA Class I: An Evolving Relationship

Successful vaccine development for infectious diseases has largely been achieved in settings where natural immunity to the pathogen results in clearance in at least some individuals. HIV presents an additional challenge in that natural clearance of infection does not occur, and the correlates of immune protection are still uncertain. However, partial control of viremia and markedly different outcomes of disease are observed in HIV-infected persons. Here, we examine the antiviral mechanisms implicated by one variable that has been consistently associated with extremes of outcome, namely HLA class I alleles, and in particular HLA-B, and examine the mechanisms by which this modulation is likely to occur and the impact of these interactions on evolution of the virus and the host. Studies to date provide evidence for both HLA-dependent and epitope-dependent influences on viral control and viral evolution and have important implications for the continued quest for an effective HIV vaccine (read more)