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Introduction: Posterior reversible encephalopathy syndrome (PRES) is a serious neurological syndrome that may develop following immunosuppressive therapy for stem cell transplantation (SCT). We report 8 patients with sickle cell disease (SCD) who developed PRES, which is likely to be related to immunosuppression., Methods: This is retrospective cohort analysis of the SCD registry at the King Faisal Specialist Hospital and Research Center (KFSHRC) in Riyadh, Saudi Arabia. Inclusion criteria included all adults SCD patients who underwent SCT from 2011 until 2022. We explored all cases of PRES in patients with SCT. PRES was diagnosed with MRI imaging showing reversible vasogenic cerebral edema associated with neurological symptoms including severe headache, seizures, encephalopathy, delirium, and visual disturbances., Results: During ten years follow-up (2011-2022) we found 8 patients with PRES (age range between 14 to 37 years at diagnosis) PRES occurred 8 to 124 days following SCT in 7 cases and one patient developed PRES 8 months prior to SCT. All patients were on immunosuppressive medications, including tacrolimus, cyclosporine, sirolimus and or mycophenolate mofetil. Headache, seizures, visual hallucinations, confusion, and drowsiness were the most common presenting symptoms. MRI showed abnormalities in the occipital, parietal and frontal lobes in most cases. Recovery was complete in all patients and no recurrences were noted. Two patients had graft versus host disease (GVHD). We compared risk factors for PRES among the 8 cases and 136 SCT in SCD patients who did not develop PRES. There was a significant association between PRES and imaging abnormalities, including previous bi-hemispheric infarctions ( p  = 0.001), and cerebral microbleeds (CBMs). PRES was strongly associated with presence ( p  = 0.006), size ( p  = 0.016) and number ( p  = 0.005) of CMBs., Conclusion: PRES can develop days to weeks following SCT in patients with SCD, and is associated with immunosuppressive therapy, previous bi-hemispheric infarctions and CMB. Prompt recognition and intervention leads to good recovery., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 BinAmir, AlAhmari, AlQahtani, Mohamed, Alotaibi, AlShamrani, AlSaeed, AlGhanmi, Heji, Alreshaid, AlKawi, AlHazzani, AlZawahmah, Shuaib, Al-Ajlan and AlMohareb.)

Background and Objectives: Prognostic factors reliably predicting outcomes for critically ill adolescent and young adult (AYA) patients undergoing allogeneic hematopoietic cell transplantation (allo-HSCT) are lacking. We assessed transplant and intensive care unit (ICU)-related factors impacting patient outcomes., Patients and Methods: AYA patients who underwent allo-HSCT and required ICU admission at a Tertiary care Centre, during the period of 2003-2013, were included in this retrospective review. This was a non-interventional study. Only outcomes after the first allo-HSCT and index ICU admissions were analyzed. Disease-, transplant-, and ICU-related variables were analyzed to identify risk factors predictive of survival., Results: Overall, 152 patients were included (males, 60.5%); median age at transplantation was 24 years (interquartile range [IQR] 18-32.5); median age at admission to the ICU was 25.8 years (IQR 19-34). Eighty-four percent underwent transplantation for a hematological malignancy; 129 (85%) received myeloablative conditioning. Seventy-one percent of ICU admissions occurred within the first year after allo-HSCT. ICU admission was primarily due to respiratory failure (47.3%) and sepsis (43.4%). One hundred and three patients (68%) died within 28 days of ICU admission. The 1- and 5-year overall survival rates were 19% and 17%, respectively. Main causes for ICU-related death were refractory septic shock with multiorgan failure (n = 49, 32%) and acute respiratory distress syndrome (ARDS) (n = 39, 26%). Univariate analysis showed that ICU mortality was associated with an Acute Physiology and Chronic Health Evaluation (APACHE) II score >20, a sequential organ failure assessment (SOFA score) > 12, a high lactate level, anemia, thrombocytopenia, leukopenia, hyperbilirubinemia, a high international normalized ratio (INR) and acute graft-versus-host disease (GVHD). Multivariate analysis identified thrombocytopenia, high INR, and acute GVHD as independent predictors of mortality., Conclusions: In AYA allo-HSCT patients admitted to the ICU, mortality remains high. Higher SOFA and APACHE scores, the need for organ support, thrombocytopenia, coagulopathy, and acute GVHD predict poor outcomes.

Haploidentical donor (haplo-) hematopoietic stem cell transplantation (HSCT) with post-transplantation cyclophosphamide (PTCy) is now performed on a large scale worldwide. Our patient outcomes did not completely reflect the results published by other groups. We herein present the results of 60 patients with hematologic malignancies treated homogeneously on a modified version of the standard protocol by adding ATG as an additional graft-versus-host disease (GVHD) prophylaxis measure. This was a retrospective analysis of 60 haplo-HSCT recipients using a myeloablative conditioning regimen with antithymocyte globulin and PTCy for GVHD prophylaxis. At 5 years, overall survival was 59.2%, relapse-free survival (RFS) was 48.6%, and chronic GVHD (cGVHD) and relapse-free survival was 40%. The median time to neutrophil and platelet engraftment was 16 days and 28.5 days, respectively. The rates of grade II-IV acute GVHD and extensive cGVHD were 46.7% and 23.3%, respectively. The cumulative incidence of relapse was 30%, nonrelapse mortality was 21.6%, and transplantation-related mortality was 11%. Higher Disease Risk Index and 50% HLA match were associated with lower RFS. Female donor to male recipient and older donor age were associated with an elevated risk of cGVHD. The use of PTCy might not yield the same results in different populations. Many remaining questions need to be addressed in randomized trials, including optimal graft source and donor, date of calcineurin inhibitor initiation, personalized or targeted dose of PTCy, immune reconstitution, and others., (Copyright © 2024 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Background Aims: Graft failure after allogeneic transplant for aplastic anemia is problematic. The risk of graft failure depends on multiple variables, including the preparative regimen, donor type, stem cell dose and source among other variables., Methods: We performed a retrospective analysis of patients with aplastic anemia who underwent matched-sibling allogeneic transplant at a single center., Results: We identified 82 patients who fit the inclusion criteria. One had primary graft failure and was excluded from this analysis. The recipient median age was 22 years. The donor median age was 23 years. The median time from diagnosis to transplant was 1.6 months. The median number of red cell transfusions before transplant was nine. The median number of platelet transfusions before transplant was 18. Thirteen patients developed secondary graft failure, with a cumulative incidence at 5 years of 16% and median time to develop secondary graft failure of 129 days. All patients engrafted with a median time for neutrophil engraftment of 19 days and a median time for platelet engraftment of 22 days. The survival of patients with or without secondary graft failure was not different. Major or bidirectional ABO incompatibility and older recipient age were statistically significantly associated with greater risk of secondary graft failure., Conclusions: Secondary graft failure is a significant complication after allogeneic transplant for SAA. Identification of recipients at risk and mitigating the potential risks of this complication is warranted., Competing Interests: Declaration of Competing Interest The authors have no commercial, proprietary or financial interest in the products or companies described in this article., (Copyright © 2023 International Society for Cell & Gene Therapy. Published by Elsevier Inc. All rights reserved.)

Aim: The outcome of T-cell acute lymphoblastic leukemia (T-ALL) has improved with the use of pediatric-inspired protocols in the adolescents and young adults (AYA) population. There is limited literature regarding the outcome of T-ALL/lymphoblastic lymphoma (LBL) AYA patients treated with pediatric protocols., Methods: A total of 35 T-ALL/LBL-AYA patients ages between 14 and 55 years were treated with AYA-15 protocol., Results: At a median follow-up of 5 years the overall survival, disease-free survival and event-free survival are 71%, 62% and 49.6% respectively. Toxicities were within the expected range., Conclusion: Our single-center experience real-world data in treating T-ALL/LBL-AYA patients with pediatric-inspired protocol demonstrates encouraging results of high survival rate and excellent tolerability for patients aged 18-55 years., (© 2023 Amr Hanbali.)

Dendritic cell (DC) vaccines are promising for immunotherapy, and their production using CD34 + hematopoietic stem cells (HPSCs) from patients with chronic myelogenous leukemia (CML) and healthy donors is well established. However, the generation of CD1a + CD14 - DCs and their functional properties in patients with CML remain elusive. Here, we aimed to study the biology of DCs generated from CD34 -/low HPSCs and evaluate the status of their BCR/ABL translocation, ability to stimulate T cells, and capacity of endocytosis compared to DCs derived from CD34 + HPSCs from both patients with CML and healthy donors. CD1a + CD14 - DCs were generated from CD34 -/low HPSCs and evaluated morphologically and functionally. CD34 + cells are frequently selected for transplantation and the entire CD34 -/low HPSC fraction is wasted. Here, we anticipated the CD34 - HPSC subset to constitute an invaluable source for acquiring DCs for immunotherapy. CD34 + and CD34 - HPSCs were sorted from the bone marrow samples of CML patients and healthy donors and differentiated ex vivo in a similar way. DCs from CD34 - Lin - and CD34 + Lin - HPSCs expressed comparable surface markers (CD80, CD83, CD86, HLA-DR, CD40, and CD54). Functional analysis revealed that DCs acquired from both subsets retained a potent allogeneic T cell stimulatory capacity and an efficient phagocytic ability and showed a similar BCR/ABL translocation status. In conclusion, DCs were successfully differentiated from the CD34 - Lin - cell subset and showed potent functional capacities, indicating their potential for application in immunotherapy and basic research., Competing Interests: None., (AJTR Copyright © 2023.)

The recommended therapy for severe aplastic anemia (SAA) in younger patients with a matched sibling donor (MSD) is allogeneic hematopoietic cell transplantation (allo-HCT). A number of conditioning regimens and protocols have been used for these patients. Here we report a homogeneous cohort of SAA patients receiving a uniform transplantation protocol. This study is a retrospective analysis of 82 consecutive patients with SAA who underwent MSD allo-HCT at a single center. The median duration of follow-up for survivors was 100 months, the 10-year overall survival (OS) was 87.5%, and the 10-year event-free survival was 75.3%. The OS was 97.4% for "mobilized" bone marrow (BM) graft recipients and 78.9% for "nonmobilized" BM graft recipients (P = .01. The cumulative incidence of acute graft-versus-host disease (GVHD) was 25.6%, that of chronic GVHD was 27.16%, and that of graft failure was 16.2%. Recipient age ≥30 years and transplantation at >6 months after SAA diagnosis were associated with a increased risk of events. In the presence of a fully matched sibling donor, allo-HCT with a mobilized BM graft and fludarabine-cyclophosphamide conditioning is an efficacious and safe approach. Early transplantation is associated with a better outcome, emphasizing the importance of not delaying transplantation in these patients. Prospective trials are needed to determine the optimal regimen., (Copyright © 2021 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Background: Treating adolescents and young adults (AYA) patients with acute lymphoblastic leukemia (ALL) using pediatric-inspired protocols have shown improvement in outcomes. Most data available in the literature of such protocols is derived from well-controlled clinical trials. This report aims to provide a real-world experience from using a pediatric-inspired protocol in ALL-AYA population in larger number of patients treated at a national tertiary care referral center., Methods: Newly diagnosed Philadelphia negative ALL-AYA patients ages between 14 and 55 years of age were treated on an institutional protocol (AYA-15 protocol) adopted from a modified version of Children's Cancer Group (CCG) 1900 protocol. At the time of this publication, a total of 79 patients were treated using the AYA-15 protocol between 2015 and 2020). Event-free survival (FFS), disease-free survival (DFS), and overall survival (OS) were analyzed using cumulative incidence and Kaplan-Meier methods., Results: The median age at diagnosis was 18 years (14-51 years) with 63% male patients. Complete remission (CR) at day 28 of induction was achieved in 88.6% of which 73.4% were minimal residual disease (MRD) negative. At a median follow up of 5 years, EFS, DFS and OS were 57.5%, 69.2% and 75.8% respectively. Toxicities were within the expected range with infections and transaminitis being the most common adverse events., Conclusion: Our single-center experience real-world data in treating AYA-ALL patients with pediatric-inspired protocol demonstrates encouraging results of high survival rate and excellent tolerability for patients aged 18-55 years., Competing Interests: We declare that this manuscript has not been published elsewhere and it has not been submitted simultaneously for publication elsewhere. All authors don't have financial disclosure or conflict of interest, (© 2021 Published by Elsevier Ltd.)

Saudi Arabia is the largest of the Arabian Gulf countries with a total population of 33.41 million as of 2017. This report summarizes the experience from four leading tertiary care hematopoietic stem cell transplantation (HSCT) centers in Saudi Arabia representing more than 90% of all HSCTs performed in the country. Between 1984 and 2016, a total of 6,184 HSCTs were performed. Of these, 3,586 HSCTs were performed in adults and 2,598 HSCTs were performed in pediatric patients. Malignancy was the main indication for transplantation (47%). While most transplants were performed from an identical sibling donor, HSCTs from cord blood, unrelated and, more recently, haploidentical donors have also been performed. Relative shortage of HSCT bed capacity is perceived to be a limiting factor in Saudi Arabia. Lately, more HSCT centers are emerging with rapid growth, which may significantly improve the access to HSCT in the country in the near future., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 King Faisal Specialist Hospital & Research Centre. Published by Elsevier Ltd. All rights reserved.)

Secondary acute myeloid leukemia (sAML) includes AML as a complication of an antecedent hematological disorder or a therapy-related AML. Large registry-based data identified sAML as an independent poor-outcome type of AML post allogeneic hematopoietic cell transplantation (allo-HCT). In our study, we tried to define factors affecting outcomes of sAML post allo-HCT, and identify patients with sAML who may truly benefit from allo-HCT. We retrospectively analyzed the data of 64 patients aged (14-61 years) with sAML who received allo-HCT between September 2010 and February 2018 at our institute. Most of the patients were transplanted from matched related donors (MRD; 54, 84.4%). Our results showed that poor-risk cytogenetics were identified in 31 patients (48.4%), and their presence was an indicator of poor overall survival (OS) and disease-free survival (DFS; P -value = .009, and .004, respectively). The cumulative incidence of chronic graft-versus-host disease (cGVHD) was significantly lower in sAML patients with poor-risk cytogenetics ( P -value = .003) resulting in a high risk of death without cGVHD in this group of patients ( P -value = .02). Besides, GVHD relapse-free survival (GRFS) analysis showed that most of our studied patients experienced either relapse or debilitating grade II-IV cGVHD in the first 2 years post allo-HCT. We conclude that sAML patients with poor-risk cytogenetics have a significantly lower DFS post allo-HCT with a high risk of death without active cGVHD., Competing Interests: The authors declare that there is no conflict of interest., (© 2020 The Authors. eJHaem published by British Society for Haematology and John Wiley & Sons Ltd.)

Autosomal recessive mutations in G6PC3 cause isolated and syndromic congenital neutropenia which includes congenital heart disease and atypical inflammatory bowel disease (IBD). In a highly consanguineous pedigree with novel mutations in G6PC3 and MPL , we performed comprehensive multi-omics analyses. Structural analysis of variant G6PC3 and MPL proteins suggests a damaging effect. A distinct molecular cytokine profile (cytokinome) in the affected proband with IBD was detected. Liquid chromatography-mass spectrometry-based proteomics analysis of the G6PC3-deficient plasma samples identified 460 distinct proteins including 75 upregulated and 73 downregulated proteins. Specifically, the transcription factor GATA4 and LST1 were downregulated while platelet factor 4 (PF4) was upregulated. GATA4 and PF4 have been linked to congenital heart disease and IBD respectively, while LST1 may have perturbed a variety of essential cell functions as it is required for normal cell-cell communication. Together, these studies provide potentially novel insights into the pathogenesis of syndromic congenital G6PC3 deficiency., Competing Interests: The authors declare no competing interests., (© 2021 The Author(s).)

Sickle cell disease (SCD) affects more than 300,000 children annually worldwide. Despite improved supportive care, long-term prognosis remains poor. Allogeneic hematopoietic cell transplantation (allo-HCT) is the sole validated curative option, resulting in sustained resolution of the clinical phenotype. The medical literature on allo-HCT for SCD is largely limited to children. Recent studies have evaluated allo-HCT efficacy in adults. Here, we conducted a systematic review/meta-analysis to assess the totality of evidence on the efficacy, or lack thereof, of allo-HCT in treating SCD. We performed a comprehensive literature search using PubMed/Medline, Embase, and Cochrane library databases on November 13, 2019. Four authors independently extracted data on clinical outcomes related to benefits (overall survival [OS] and disease-free survival [DFS]) and harms (acute graft-versus-host disease [aGVHD], chronic graft-versus-host disease [cGVHD], nonrelapse mortality [NRM], and graft failure [GF]). Our search identified a total of 1906 references. Only 33 studies (n= 2853 patients) met our inclusion criteria. We also performed a subset analysis by age. Analyses of all-age groups showed pooled rates of 96% for OS, 90% for DFS, 20% for aGVHD, 10% for cGVHD, 4% for NRM, and 5% for GF. In the pediatric population, pooled rates for OS, DFS, aGVHD, cGVHD, NRM, and GF were 97%, 91%, 26%, 11%, 5%, and 3%, respectively. In adults, pooled rates for OS, DFS, aGVHD, cGVHD, NRM, and GF were 98%, 90%, 7%, 1%, 0%, and 14%, respectively. Our data show that allo-HCT is safe and effective, yielding pooled OS rates exceeding 90%. The high GF rate of 14% in adults is concerning and emphasizes the need to evaluate new strategies., (Copyright © 2020 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Acute myeloid leukemia (AML) with t(8;21)(q22;q22.1);RUNX1-RUNX1T1, one of the core-binding factor leukemias, is one of the most common subtypes of AML with recurrent genetic abnormalities and is associated with a favorable outcome. The translocation leads to the formation of a pathological RUNX1-RUNX1T1 fusion that leads to the disruption of the normal function of the core-binding factor, namely, its role in hematopoietic differentiation and maturation. The consequences of this alteration include the recruitment of repressors of transcription, thus blocking the expression of genes involved in hematopoiesis, and impaired apoptosis. A number of concurrent and cooperating mutations clearly play a role in modulating the proliferative potential of cells, including mutations in KIT, FLT3, and possibly JAK2. RUNX1-RUNX1T1 also appears to interact with microRNAs during leukemogenesis. Epigenetic factors also play a role, especially with the recruitment of histone deacetylases. A better understanding of the concurrent mutations, activated pathways, and epigenetic modulation of the cellular processes paves the way for exploring a number of approaches to achieve cure. Potential approaches include the development of small molecules targeting the RUNX1-RUNX1T1 protein, the use of tyrosine kinase inhibitors such as dasatinib and FLT3 inhibitors to target mutations that lead to a proliferative advantage of the leukemic cells, and experimentation with epigenetic therapies. In this review, we unravel some of the recently described molecular pathways and explore potential therapeutic strategies., (© 2020 by The American Society of Hematology.)

Background: Patients undergoing hematopoietic stem cell transplantation (HSCT) are often referred for physical therapy (PT) to help improve their quality of life. However, to our knowledge there is no clear PT pathway to guide therapists and patients before, during, and after HSCT., Methods: A comprehensive literature review was carried out exploring the role and benefits of PT in HSCT patients. The current evidence was comlimented with recommendations and opinions from the experts in the field, which included PT's and hematology consultants from PTAGVHD and the EMBMT group., Result: A clear pathway and protocol as a working guide for rehabilitation professionals working with the HSCT patient's was developed., Conclusion: This paper not only reviews the current evidence on safe PT practice but also puts forward a protocol and pathway for HSCT rehabilitation, highlights the importance of individualized exercise intervention for HSCT patients, and outlines safe practice guidelines for the physical therapists working in this field., (Copyright © 2019 King Faisal Specialist Hospital & Research Centre. Published by Elsevier Ltd. All rights reserved.)

In adult hematopoietic cell transplantation (HCT), filgrastim-mobilized peripheral blood (G-PB) has largely replaced unstimulated marrow for allografting. Although the use of G-PB results in faster hematopoietic recovery, it is also associated with more chronic graft-versus-host disease (cGVHD). A potential alternative allograft is filgrastim-stimulated marrow (G-BM), which we hypothesized may be associated with prompt hematopoietic recovery but with less cGVHD. We conducted a phase 3, open-label, multicenter randomized trial of 230 adults with hematologic malignancies receiving allografts from siblings after myeloablative conditioning to compare G-PB with G-BM. The primary endpoint was time to treatment failure, defined as a composite of extensive cGVHD, relapse/disease progression, and death. With a median follow-up of 36 months (range, 9.6 to 48), comparing G-BM with G-PB, there was no difference between the 2 arms with respect to the primary outcome of this study (hazard ratio [HR], .91; 95% confidence interval [CI], .68 to 1.22; P = .52). However, the cumulative incidence of overall cGVHD was lower with G-BM (HR, .66; 95% CI, .46 to .95; P = .007) and there was no difference in the risk of relapse or progression (P = .35). The median times to neutrophil recovery (P = .0004) and platelet recovery (P = .012) were 3 days shorter for recipients allocated to G-PB compared with those allocated to G-BM, but there were no differences in secondary engraftment-related outcomes, such as time to first hospital discharge (P = .17). In addition, there were no graft failures in either arm. This trial demonstrates that, compared with G-PB, the use of G-BM allografts leads to a significantly lower rate of overall cGVHD without a loss of the graft-versus-tumor effect and comparable overall survival. Our findings suggest that further study of this type of allograft is warranted., (Copyright © 2016 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.)

Hematopoietic stem cell transplantation (HSCT) activity was surveyed in the 9 countries in the World Health Organization Eastern Mediterranean region that reported transplantation activity. Between the years of 1984 and 2007, 7933 transplantations were performed. The number of HSCTs per year has continued to increase, with a plateau in allogeneic HSCT (allo-HSCT) between 2005 and 2007. Overall, a greater proportion of transplantations were allo-HSCT (n = 5761, 77%) compared with autologous HSCT (ASCT) (n = 2172, 23%). Of 5761 allo-HSCT, acute leukemia constituted the main indication (n = 2124, 37%). There was a significant proportion of allo-HSCT for bone marrow failures (n = 1001, 17%) and hemoglobinopathies (n = 885, 15%). The rate of unrelated donor transplantations remained low, with only 2 matched unrelated donor allo-HSCTs reported. One hundred umbilical cord blood transplantations were reported (0.017% of allo-HSCT). Peripheral blood stem cells were the main source of graft in allo-HSCT, and peripheral blood stem cells increasingly constitute the main source of hematopoietic stem cells overall. Reduced-intensity conditioning was utilized in 5.7% of allografts over the surveyed period. ASCT numbers continue to increase. There has been a shift in the indication for ASCT from acute leukemia to lymphoproliferative disorders (45%), followed by myeloma (26%). The survey reflects transplantation activity according to the unique health settings of this region. Notable differences in transplantation practices as reported to the European Group for Blood and Marrow Transplantation over recent years are highlighted., (Copyright © 2011 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.)

Compelling evidences indicate a key role for regulatory T cells (T(reg)) on the host response to cancer. The Wilms' tumor antigen (WT1) is overexpressed in several human leukemias and thus considered as promising target for development of leukemia vaccine. However, recent studies indicated that the generation of effective WT1-specific cytotoxic T cells can be largely affected by the presence of T(regs). We have generated T-cell lines and clones that specifically recognized a WT1-84 (RYFKLSHLQMHSRKH) peptide in an HLA-DRB1*0402-restricted manner. Importantly, they recognized HLA-DRB1*04-matched fresh leukemic cells expressing the WT1 antigen. These clones exerted a T helper 2 cytokine profile, had a CD4(+)CD25(+)Foxp3(+)GITR(+)CD127(-) T(reg) phenotype, and significantly inhibited the proliferative activity of allogeneic T cells independently of cell contact. Priming of alloreactive T cells in the presence of T(regs) strongly inhibited the expansion of natural killer (NK), NK T, and CD8(+) T cells and had an inhibitory effect on NK/NK T cytotoxic activity but not on CD8(+) T cells. Furthermore, priming of T cells with the WT1-126 HLA-A0201-restricted peptide in the presence of T(regs) strongly inhibited the induction of anti-WT1-126 CD8(+) CTL responses as evidenced by both very low cytotoxic activity and IFN-gamma production. Moreover, these T(reg) clones specifically produced granzyme B and selectively induced apoptosis in WT1-84-pulsed autologous antigen-presenting cells but not in apoptotic-resistant DR4-matched leukemic cells. Importantly, we have also detected anti-WT1-84 interleukin-5(+)/granzyme B(+)/Foxp3(+) CD4(+) T(regs) in five of eight HLA-DR4(+) acute myeloid leukemia patients. Collectively, our in vitro and in vivo findings strongly suggest important implications for the clinical manipulation of T(regs) in cancer patients.