IntroductionA viable option for high-risk, acute leukemia patients without matched donors is hematopoietic stem cell transplantation (HSCT) from human leukocyte antigen (HLA)-haploidentical 3-locimismatched family members who were readily available for almost all patients. 1,2 Until the 1990s, full-haplotype-mismatched, T cell-replete transplantations were unsuccessful because donoralloreactive T cells triggered a high incidence of severe graft-versushost disease (GVHD) despite posttransplantation immune suppression. 3,4 The breakthrough came with the use of a megadoses of extensively ex vivo T cell-depleted peripheral blood hematopoietic progenitor cells and a highly myeloablative conditioning regimen containing antithymocyte globulin (ATG), which exerts additional T-cell depletion in vivo. This approach ensures a high rate of primary engraftment in the absence of GVHD, 5 with more than 40% long-term event-free survival and excellent quality of life. 1,2 However, extensive ex vivo and in vivo T-cell depletion delays the recovery of immune responses against pathogens, leading to a high incidence of life-threatening infections. 1,2 Strategies to hasten posttransplantation immune reconstitution without triggering GVHD have included infusion of donor T cells after engineering with a suicide gene, 6 photodynamic purging, 7 and the use of an anti-CD25 monoclonal antibody (mAb) 8 to remove alloreactive cells. An alternative strategy might be based on donor CD4 ϩ CD25 ϩ T-regulatory cells (Tregs). In murine models of HSCT across major histocompatibility complex barriers, CD4 ϩ CD25 ϩ Tregs suppressed lethal GVHD 9 and favored posttransplantation immune reconstitution when coinfused with conventional T cells (Tcons). 10 The main obstacle to clinical application of human Tregs is their paucity in the peripheral blood. Although ex vivo-expanded polyclonal 11 or recipient-specific Tregs 12 were proposed to circumvent this potential barrier, we opted for closed, automated immunoselection 13 of naturally occurring Tregs. In the present study, for the first time in humans, we show that the early infusion of freshly isolated donor Tregs followed by Tcons at the time of full-haplotypemismatched HSCT prevented GVHD while favoring Tconmediated posttransplantation immune reconstitution. MethodsStudy design, conditioning regimen, stem cell mobilization, and supportive careIn 2008, the Umbria Regional Hospital Ethics Committee (CEAS Umbria) approved the protocol entitled "Adoptive Immunotherapy with Natural Regulatory T cells (Treg) and Effector T Cells in Allogeneic Hematopoietic Stem Cell Transplantation from 2-3 Loci Mismatched HLA-Haploidentical Family Donors for Patients with High Risk Haematologic Malignancies" (Protocol No 01/08). Written informed consent was obtained for all patients and donors in accordance with the Declaration of Helsinki. Inclusion criteria were: acute myeloid leukemia (AML) or acute lymphoid leukemia (ALL) in remission at high risk of relapse; acute leukemia with primary induction failure, in chemoresist...

Posttransplant relapse is still the major cause of treatment failure in high-risk acute leukemia. Attempts to manipulate alloreactive T cells to spare normal cells while killing leukemic cells have been unsuccessful. In HLA-haploidentical transplantation, we reported that donor-derived T regulatory cells (Tregs), coinfused with conventional T cells (Tcons), protected recipients against graft-versus-host disease (GVHD). The present phase 2 study investigated whether Treg-Tcon adoptive immunotherapy prevents posttransplant leukemia relapse. Forty-three adults with high-risk acute leukemia (acute myeloid leukemia 33; acute lymphoblastic leukemia 10) were conditioned with a total body irradiation-based regimen. Grafts included CD34(+) cells (mean 9.7 × 10(6)/kg), Tregs (mean 2.5 × 10(6)/kg), and Tcons (mean 1.1 × 10(6)/kg). No posttransplant immunosuppression was given. Ninety-five percent of patients achieved full-donor type engraftment and 15% developed ≥grade 2 acute GVHD. The probability of disease-free survival was 0.56 at a median follow-up of 46 months. The very low cumulative incidence of relapse (0.05) was significantly better than in historical controls. These results demonstrate the immunosuppressive potential of Tregs can be used to suppress GVHD without loss of the benefits of graft-versus-leukemia (GVL) activity. Humanized murine models provided insights into the mechanisms underlying separation of GVL from GVHD, suggesting the GVL effect is due to largely unopposed Tcon alloantigen recognition in bone marrow.

No abstract

The C-type lectin receptor Dectin-1 plays a pivotal role in antifungal immunity. In this study, the recently characterized human DECTIN1 Y238X early stop codon polymorphism leading to diminished Dectin-1 receptor activity was studied in relation to invasive aspergillosis susceptibility and severity in patients receiving hematopoietic stem cell transplantation. We found that the presence of the DECTIN1 Y238X polymorphism in either donors or recipients of hematopoietic stem cell transplantation increased susceptibility to aspergillosis, with the risk being highest when the polymorphism was present simultaneously in both donors and recipients (adjusted hazard ratio ‫؍‬ 3.9; P ‫؍‬ .005). Functionally, the Y238X polymorphism impaired the production of interferon-␥ and interleukin-10 (IL-10), in addition to IL-1␤, IL-6, and IL-17A, by human peripheral mononuclear cells and Dectin-1 on human epithelial cells contributed to fungal recognition. Mechanistically, studies on preclinical models of infection in intact or bone marrow-transplanted Dectin-1 knockout mice revealed that protection from infection requires a distinct, yet complementary, role of both donor and recipient Dectin-1. This study discloses Dectin-1 deficiency as a novel susceptibility factor for aspergillosis in high-risk patients and identifies a previously unsuspected role for Dectin-1 in antifungal immunity that is the ability to control both resistance and tolerance to the fungus contingent on hematopoietic/ nonhematopoietic compartmentalization. (Blood. 2010;116(24):5394-5402) IntroductionAspergillus spp are ubiquitous in nature, and the spectrum of diseases they cause is myriad, including saprophytic colonization of preexisting cavities (aspergilloma), allergic asthma, hypersensitivity pneumonitis, allergic bronchopulmonary aspergillosis occurring as a complication of bronchial asthma or cystic fibrosis, and disseminated disease associated with high mortality rates in patients with hematologic malignancies and recipients of solid organs and stem cell transplantations. 1 Immunocompetent and nonatopic subjects are relatively resistant to infections, and disease occurs in the setting of host damage. 2 The association of persistent inflammation with intractable infection is common in nonneutropenic patients after hematopoietic stem cell transplantation (HSCT) as well as in allergic fungal diseases. 2 The current understanding of the pathophysiology underlying Aspergillus infection and disease highlights a truly bipolar nature of the inflammatory process in infection. Early inflammation prevents or limits infection, but an uncontrolled response may eventually oppose disease eradication. This condition is crucially exemplified in mice with chronic granulomatous disease, in which an intrinsic, genetically determined failure to control inflammation to sterile fungal components determines the animals' inability to resolve an actual infection with A fumigatus. 3 A main implication of these findings is that, at least in specific clinical settings, it is an exag...

No abstract

Abstract Essential thrombocythemia (ET) is characterized by abnormal megakaryopoiesis and enhanced thrombotic risk. Once-daily low-dose aspirin is the recommended antithrombotic regimen, but accelerated platelet generation may reduce the duration of platelet cyclooxygenase-1 (COX-1) inhibition. We performed a multicenter double-blind trial to investigate the efficacy of 3 aspirin regimens in optimizing platelet COX-1 inhibition while preserving COX-2–dependent vascular thromboresistance. Patients on chronic once-daily low-dose aspirin (n = 245) were randomized (1:1:1) to receive 100 mg of aspirin 1, 2, or 3 times daily for 2 weeks. Serum thromboxane B2 (sTXB2), a validated biomarker of platelet COX-1 activity, and urinary prostacyclin metabolite (PGIM) excretion were measured at randomization and after 2 weeks, as primary surrogate end points of efficacy and safety, respectively. Urinary TX metabolite (TXM) excretion, gastrointestinal tolerance, and ET-related symptoms were also investigated. Evaluable patients assigned to the twice-daily and thrice-daily regimens showed substantially reduced interindividual variability and lower median (interquartile range) values for sTXB2 (ng/mL) compared with the once-daily arm: 4 (2.1-6.7; n = 79), 2.5 (1.4-5.65, n = 79), and 19.3 (9.7-40; n = 85), respectively. Urinary PGIM was comparable in the 3 arms. Urinary TXM was reduced by 35% in both experimental arms. Patients in the thrice-daily arm reported a higher abdominal discomfort score. In conclusion, the currently recommended aspirin regimen of 75 to 100 once daily for cardiovascular prophylaxis appears to be largely inadequate in reducing platelet activation in the vast majority of patients with ET. The antiplatelet response to low-dose aspirin can be markedly improved by shortening the dosing interval to 12 hours, with no improvement with further reductions (EudraCT 2016-002885-30).

No abstract

[No abstract available