Infections due to alphaherpesviruses in early post-transplant period after allogeneic haematopoietic stem cell transplantation: Results of a 5-year survey

BackgroundInfections caused by human α-herpesviruses usually have a benign course with recurrencies. However, they may become dangerous in immunocompromised hosts. In this case, molecular methods constitute a reliable diagnostic tool enabling rapid assessment of the efficacy of antiviral treatment strategies.ObjectivesWe estimated the frequency of alphaherpesviral DNAemia and the viral load during early post-transplantation period after alloHSCT; we also analyzed association of the DNAemia and chosen parameters of the patients.Study designA cohort of 190 alloHSCT recipients from two hospitals in Warsaw, Poland, was examined weekly during 100-day early post-transplantation period using quantitative real time PCR assays. A total of 2475 sera samples were evaluated for the presence of α-herpesviral DNA in patients, of whom 117 (62%) received unrelated grafts, while the remaining 73 (38%) received grafts from sibling donors. All patients received standard antiviral prophylaxis with acyclovir. In the examined group, anti-HSV-1, anti-HSV-2 and anti-VZV IgGs were examined prior to transplantation,ResultsWithin the study period, DNA of α-herpesviruses was detected in 44 patients (23.2%). Most patients tested positive for HSV-1 DNA (43 patients, 22.6%), single patient for HSV-2, and no patient positive for VZV. Clinical symptoms such as pneumonia, skin changes, elevated levels of aminotransferases were observed in five patients, four of these patients presented symptoms of GvHD at the same time. (2,6%). Statistics shows that GvHD (P < 0.001) and matched unrelated donor as a source of HSCT (P = 0.048) are associated with the development of HSV-1 DNAemia.ConclusionsAlthough our data demonstrate frequent reactivation of HSV-1 in the early post-transplant period, the rate of symptomatic infections was low. We did not find association between HSV-1 viremia and mortality, but significant association with GvHD and donor source was observed.     

Long-term outcome of myeloablative allogeneic stem cell transplantation for multiple myeloma.

Allogeneic stem cell transplantation (alloSCT) has been used in the hopes of harnessing the curative potential of the graft-versus-myeloma effect. This study examines the long-term outcomes of a large cohort of patients with myeloma who were treated with myeloablative alloSCT at a single center. Comparisons are made with those who were treated with autologous stem cell transplantation (ASCT). Between January 1989 and February 2002, 158 patients age10 years post myeloablative alloSCT, similarly there are long-term survivors post-ASCT. Myeloablative alloSCT should not be considered standard treatment, and should only be considered in the context of a clinical trial.     

CTLA-4 polymorphism and clinical outcome post allogeneic hematopoietic stem cell transplantation

CTLA-4 inhibitory molecule plays an important role in regulating T cell activation. It is considered a crucial element in keeping the immune balance and has been implicated in cancer, autoimmunity and transplantation immunology. Inconsistent observations are reported regarding its association with hematopoietic stem cell transplantation (HSCT). Genotyping of CTLA-4 was performed in recipients and their HLA-matched donors for +49A/G and CT60 polymorphisms (80 and 94 pairs, respectively) using PCR-RFLP. No association was encountered between both polymorphisms in patients and donors and acute or chronic graft versus host disease. Significant association was observed between recipient +49A/G G allele and lower disease-free survival and overall survival compared to AA genotype (HR: 2.17, p = 0.03, 95% CI: 1.05–4.48 and HR: 2.54, p = 0.01, 95% CI: 1.16–5.54), respectively. Our results suggest that CTLA-4 genotyping may predict outcome in patients post HSCT. To validate our results, further studies on a larger cohort are needed.     

清肿瘤性异基因造血干细胞移植

标准的清髓性异基因造血干细胞移植(allo-HSCT)对于需代替治疗的造血与免疫系统的非恶性疾病,应当是合理或足够的;然而,对于恶性血液病患者,清除患者骨髓造血组织,成功重建异体正常造血与免疫系统,并不一定能完全治愈恶性血液病,因为白血病(干)细胞并非只限骨髓中存在,它可浸润骨髓之外的其他任何组织。临床实践证实,allo-HSCT后仍然有30%左右的患者疾病复发,特别是具有高危因素或难治复发患者复发率可高达40%～70%以上。这些复发的白血病细胞几乎全系源自患者移植前本身的白血病细胞,其中半数患者以髓外部位复发开始,有证据提示,清髓性移植并没有完全杀灭患者体内的白血病细胞,特别是那些对化放疗不敏感或栖居在髓外"庇护所"中的白血病干细胞,最终导致疾病复发。因此笔者提出并建立了一个清肿瘤性异体造血干细胞移植(TAHSCT)的概念,在临床上对其进行了初步的探讨。其内容贯穿于移植技术全过程的各个环节,但主要为应用个体化清肿瘤性预处理方案和加强移植后免疫治疗。     

Association of vitamin D receptor polymorphisms with the outcome of allogeneic haematopoietic stem cell transplantation

Recently, vitamin D receptor (VDR) polymorphism has been identified as an additional genetic factor associated with the outcome after allogeneic haematopoietic stem cell transplantation (HSCT) from HLA-matched sibling donors. In the present study, VDR ApaI, TaqI and FokI alleles were typed using single strand conformation polymorphism in 123 Polish recipients and their sibling or alternative donors to test the associations of VDR polymorphisms with HSCT outcome. Four VDR genotypes were identified as risk factors of acute graft-versus-host disease (aGVHD). Donor ApaI AA (OR = 7.245, P = 0.009), source of HSC (OR = 7.001, P = 0.007), transplantation from an alternative donor (OR = 6.630, P = 0.007) and donor FokI FF (OR = 4.473, P = 0.025) significantly contributed to the development of grades II-IV aGVHD, while recipient ApaI aa (OR = 3.233, P = 0.069), recipient FokI FF (OR = 2.558, P = 0.077) and female to male transplants (OR = 2.955, P = 0.099) were found to be less significant factors. In addition, the presence of ApaI aa genotype in the recipient was found to be associated with increased likelihood of death (P = 0.0228). The present study contributes to the studies demonstrating a role of VDR polymorphisms in HSCT outcome. In addition to previously described correlations of ApaI a allele and occurrence of severe grades III-IV aGVHD and (linked with ApaI aa) recipient TaqI TT genotype with aGVHD, the novel associations of recipient and donor FokI FF genotype and the increased aGVHD risk and recipient ApaI aa with survival were identified.     

Monitoring of Epstein-Barr virus load after hematopoietic stem cell transplantation for early intervention in post-transplant lymphoproliferative disease

Epstein-Barr virus (EBV)-associated post-transplant lymphoproliferative disease is a life-threatening complication following hematopoietic stem cell transplantation. A quantitative polymerase chain reaction to evaluate EBV-genome copy numbers based on a nested polymerase chain reaction and an end-point dilution was used. Applying this assay EBV load was prospectively screened weekly in 123 patients after transplantation. The results demonstrate that EBV reactivations with more than 1,000 EBV-genome copies measured in 10(5) peripheral blood mononuclear cells were observed in 31 patients (25.2%). Three patients developed lymphoproliferative disease with extremely high EBV-genome copies in peripheral blood mononuclear cells (>100,000 copies/10(5) cells) and plasma. After combined antiviral and immune therapy two of three patients showed a dramatic decrease of EBV load and survived, while the third patient died of lymphoma. A subclinical EBV reactivation was observed in 24 cases (19.5%) with EBV-genome copies in 10(5) peripheral blood mononuclear cells ranging between 2,500 and mostly 10,000. After reduction of immunosuppression the EBV levels normalized. In four patients, the high copy number of > or =80,000 copies/10(5) peripheral blood mononuclear cells and plasma positivity prompted us to start pre-emptive therapy with rituximab and cidofovir for prevention of lymphoproliferative disease. After drug administration the high EBV load was reduced remarkably. Ninety-two patients (74.8%) who had < or =1,000 copies/10(5) peripheral blood mononuclear cells did not develop EBV-associated lymphoproliferative disease. In conclusion, monitoring of EBV load is a sensitive and useful parameter in the surveillance of EBV reactivation for early intervention in EBV-associated lymphoproliferative disease as well as for follow-up of the efficacy of therapy.     

白消安在非亲缘异基因造血干细胞移植预处理中的应用

背景：口服白消安剂型胃肠道吸收不稳定,影响异基因造血干细胞疗效且毒性增加。静脉剂型白消安在国内最近几年用于临床,但在非亲缘异基因移植预处理中应用的相关报道甚少。 目的：探讨静脉剂型白消安在非亲缘异基因造血干细胞移植预处理中应用的疗效并观察其毒副作用。 方法：14例非亲缘异基因干细胞移植采用静脉剂型白消安联合环磷酰胺预处理方案,18例亲缘异基因干细胞移植采用口服白消安联合环磷酰胺预处理方案,观察两组造血重建、植入率等疗效指标及胃肠道反应、口腔黏膜炎、出血性膀胱炎、肝功能损害、移植物抗宿主病等相关毒性指标。 结果与结论：两组患者植入率均为100%。静脉剂型组肝脏毒性、口腔黏膜炎发生率明显低于口服剂型组(14% vs. 67%,7% vs. 55%),差异均有显著性意义(P < 0.01),而胃肠道反应、出血性膀胱炎、造血重建、急性移植物抗宿主病、局限性移植物抗宿主病等方面差异均无显著性意义(P > 0.05)。结果可见静脉剂型白消安应用于非亲缘异基因造血干细胞移植预处理可获得满意疗效,且毒副反应少。     

Clinical tolerance in allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (HSCT) has been a curative therapeutic option for a wide range of immune hematologic malignant and non-malignant disorders including genetic diseases and inborn errors. Once in the host, allogeneic transplanted cells have not only to ensure myeloid repopulation and immunological reconstitution but also to acquire tolerance to host human leukocyte antigens via central or peripheral mechanisms. Peripheral tolerance after allogeneic HSCT depends on several regulatory mechanisms aimed at blocking alloimmune reactivity while preserving immune responses to pathogens and tumor antigens. Patients transplanted with HSCT represent an ideal model system in humans to identify and characterize the key cellular and molecular players underlying these mechanisms. The knowledge gained from these studies has allowed the development of novel therapeutic strategies aimed at inducing long-term peripheral tolerance, which can be applicable not only in allogeneic HSCT but also in autoimmune diseases and solid-organ transplantation. In the present review, we describe Type 1 regulatory T cells, initially discovered and characterized in chimeric patients transplanted with human leukocyte antigen-mismatched HSCT, and how their presence correlates to tolerance induction and maintenance. Furthermore, we summarize different cell therapy approaches with regulatory T cells, designed to facilitate tolerance induction, minimizing pharmaceutical interventions.     

KIR-ligand mismatch in allogeneic hematopoietic stem cell transplantation

KIR-ligand mismatch in the graft-versus-host (GVH) direction between donor and recipient in allogeneic stem cell transplantation (ASCT) may trigger NK cell alloreactivity. Such KIR-ligand mismatch has been associated with improved survival after haploidentical ASCT for acute myeloid leukemia (AML). Its role in unrelated ASCT has been more controversial. In an analysis of 190 unrelated ASCTs for hematological malignancies, we observed that KIR-ligand mismatch was associated with increased transplantation related mortality (TRM) and decreased overall survival. The increased TRM was a consequence of a higher rate of infections. Thus, the presence of alloreactive NK cells can potentially interfere with effective immunity to infections in the early post-transplantation period. Here, we review the discrepancies in published reports on KIR-ligand mismatch in unrelated ASCT.     

间充质干细胞改善移植肾功能的Meta分析

BACKGROUND:In recent years, with the use of new immunosuppressive agents, the survival rate of renal graft is greatly improved, but accompanied by lots of side effects and unchanged long-term graft survival. Mesenchymal stem cells (MSCs) have aroused people’s great interest, while their efficacy in kidney transplantation remains controversial. OBJECTIVE:To evaluate the efficacy of MSCs transplantation on post-transplant renal graft function with a systematic review. METHODS:PubMed, EMBASE, the Cochrane Library database, the Cochrane Central Register of Controlled Trials, Wanfang database and China National Knowledge Infrastructure (CNKI) were searched until November 2015. Revman 5.3 was used for statistical analysis. RESULTS AND CONCLUSION:A total of 6 randomized controlled trials were included, including 1 166 patients. Meta-analysis results showed that at 1, 2 weeks and 1 month after kidney transplantation, the posttransplantation estimated glomerular filtration rates in the MSC-treated group were significantly higher than those in the control group (P < 0.05). At 1, 3, 6, 12 months after kidney transplantation, the posttransplantation serum creatinine levels showed no significant difference between the MSC-treated group and the control group (P > 0.05). To conclude, MSC-based immunosuppression regimen is superior to current standard immunotherapy in improving renal graft function in the early stage after kidney transplantation, but the clinical efficacy is diminished in the later period. Therefore, further investigation using large-scale randomized controlled trials is warranted.     

异基因造血干细胞移植治疗两例粘多糖累积症患儿

目的 探索造血干细胞移植治疗粘多糖累积症(mucopolysaccharidosis,MPS)的效果.方法 两例MPS患儿分别为MPS-Ⅰ H型和MPS-Ⅵ型,移植时年龄为23个月和18个月,均采用白舒菲20 ms/kg+环磷酰胺200 ms/ks进行预处理,干细胞分别来自9/10相合的无关供体和全相合同胞供体.结果 移植后11 d中性粒细胞达到0.5×109/L,14 d短串联重复序列.聚合酶链反应证实100%血细胞来自供体,移植后3个月疾病相关的酶活性分别达到70 mnol/h·mg和66 nmol/h·mg,移植后2年酶活性仍然维持在50.9nmoL/h·mg和44.5 nmol/h·mg.MPS-Ⅵ型患儿移植过程相当顺利,目前已随访28个月,健康状况良好.尽管MPS-Ⅰ H患儿移植中曾两次因肺炎合并急性心功能衰竭,但经紧急气管插管、机械通气等综合治疗后好转,随访至今也已25个月,目前心肺功能明显改善,肝脏缩小至正常大小,角膜混浊明显减轻,手指僵硬也有所改善.结论 异基因造血干细胞移植可用于治疗MPS-Ⅰ、MPS-Ⅵ;尽早移植可望减少移植相关并发症;移植所产生的临床效果需要更长时间的随访.     

Assessment of lineage-specific chimerism after allogeneic stem cell transplantation

IntroductionDonor lineage-specific chimerism of hematopoietic cells enables very precise monitoring of engraftment in selected cell lines after allogeneic stem cell transplantation (allo-SCT).Materials and methodsThe study group consisted of 12 acute leukemia patients who underwent allo-SCT in the Department of Hematology and Bone Marrow Transplantation in Katowice, Poland. Lineage-specific chimerism was assessed in B cells (CD19+ CD38−/+), plasma cells (CD19+ CD38++), T cells (CD3+ or CD7+ CD56−), monocytes (CD14+), and immature progenitor cells deriving from myeloid line (CD34+CD19). We also assessed erythrocyte chimerism by flow cytometry.ResultsAll patients engrafted. 8 out of 10 patients presented normal donor hematopoiesis. Lineage specific chimerism in these patients corresponded with chimerism analysis in unsorted material and with undetectable minimal residual disease (MRD). Relapse of the underlying disease was diagnosed in 2 patients. In both cases loss of donor chimerism occurred in leukemia specific cell line and corresponded with detectable MRD. One patient with secondary graft failure presented decreasing lineage specific chimerism in all subpopulations, with negative MRD status. In 10 patients normal hematopoiesis of donor-origin was assessed by flow cytometry. In one case no donor-derived erythrocytes were detected and the diagnosis of pure red cell aplasia was set.ConclusionsLineage specific chimerism as a method of high sensitivity and specificity allows for precise assessment of donor chimerism especially in clinically ambiguous situations. Assessment of erythrocyte chimerism by flow cytometry is a reliable method of monitoring erythroblastic line engraftment. Presented results are preliminary and the study is being continued.     

Uncovering the multifaceted roles played by neutrophils in allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is a life-saving procedure used for the treatment of selected hematological malignancies, inborn errors of metabolism, and bone marrow failures. The role of neutrophils in alloHSCT has been traditionally evaluated only in the context of their ability to act as a first line of defense against infection. However, recent evidence has highlighted neutrophils as key effectors of innate and adaptive immune responses through a wide array of newly discovered functions. Accordingly, neutrophils are emerging as highly versatile cells that are able to acquire different, often opposite, functional capacities depending on the microenvironment and their differentiation status. Herein, we review the current knowledge on the multiple functions that neutrophils exhibit through the different stages of alloHSCT, from the hematopoietic stem cell (HSC) mobilization in the donor to the immunological reconstitution that occurs in the recipient following HSC infusion. We also discuss the influence exerted on neutrophils by the immunosuppressive drugs delivered in the course of alloHSCT as part of graft-versus-host disease (GVHD) prophylaxis. Finally, the potential involvement of neutrophils in alloHSCT-related complications, such as transplant-associated thrombotic microangiopathy (TA-TMA), acute and chronic GVHD, and cytomegalovirus (CMV) reactivation, is also discussed. Based on the data reviewed herein, the role played by neutrophils in alloHSCT is far greater than a simple antimicrobial role. However, much remains to be investigated in terms of the potential functions that neutrophils might exert during a highly complex procedure such as alloHSCT.     

Lung transplantation for bronchiolitis obliterans after allogeneic hematopoietic stem cell transplantation

Bronchiolitis obliterans (BO) is a late onset complication of allogeneic hematopoietic stem cell transplantation (HSCT), and treatment outcome is dismal if it does not respond to immunosuppressive therapy. A 21-year-old male diagnosed with acute myeloid leukemia received an allogeneic HSCT from human leukocyte antigen- identical sibling donor. Twenty one months after transplantation, he developed progressive dyspnea and was diagnosed BO. Despite standard immunosuppressive therapy, the patient rapidly progressed to respiratory failure and Novalung® interventional lung-assist membrane ventilator was applied in the intensive care unit. Three months after the diagnosis of BO, the patient underwent bilateral lung transplantation (LT) and was eventually able to wean from the ventilator and the Novalung®. Since the LT, the patient has been under a strict rehabilitation program in order to overcome a severe lower extremity weakness and muscle atrophy. Histologic findings of the explanted lungs confirmed the diagnosis of BO. Nine months after the LT, the patient showed no signs of rejection or infectious complications, but still required rehabilitation treatment. This is the first LT performed in a patient with BO after allogeneic HSCT in Korea. LT can be an effective therapy in terms of survival for patients with respiratory failure secondary to development of BO following HSCT.     

Predicting outcome in hematological stem cell transplantation

This review summarizes recent results investigating the role of certain cytokine gene polymorphisms, including those of TNF-alpha, IFN-gamma, IL-6, IL-10 and IL-1 receptor antagonist (IL-1Ra), in allogeneic stem cell transplantation. It discusses their role in predicting outcome and the development of a genetic risk index for graft versus host disease (GvHD) in HLA-matched sibling transplants. By the comparative use of an in vitro human skin explant model, initial results suggest that certain cytokine gene polymorphisms may be associated with more severe disease.     

Association of IL-6 gene polymorphism with the outcome of allogeneic haematopoietic stem cell transplantation in Czech patients

Interleukin-6 (IL-6) is an important pro-inflammatory mediator implicated in immune-mediated complications of allogeneic haematopoietic stem cell transplantation (aHSCT). In accord with previous reports, this preliminary study on 56 donor-recipient pairs revealed IL-6-174 single nucleotide polymorphisms as a risk factor for the development of acute graft-versus-host disease and decreased survival after aHSCT.     

Transfusion protocols in hematopoietic stem cell allogeneic transplantation]

Hematopoietic stem cell (HSC) allogeneic transplantation is now commonly used as a therapeutic tool in patients with certain types of hematologic malignancies. Such patients, on account of severe pre-graft conditioning regimens, present with severe marrow aplasia justifying specific transfusion care. Given a complex immunological situation (immediately after transplantation, co-existence of two cell populations with different immunohematological characteristics), transfusion protocols must rest on clear and well-defined recommendations. Recent transfusion recommendations in settings of HSC allogeneic transplantation have defined criteria for the choice of blood products (red blood cell concentrates, plasma and platelet concentrates) depending on recipient and graft immunohematological characteristics (minor/major/mixed ABO compatibility/incompatibility and time of transplantation). Transfusion instructions are summarized in a synthesis document entitled : "Instructions for transfusion following HSC allogeneic transplantation". This document specifies the immunohematological characteristics of blood products and various transfusion protocols (systematic irradiation, negative CMV, etc.). This document is used by the teams who distribute blood products, for selection purposes, as well as by the medical transfusion team when they perform ultimate pre-transfusion control steps.     

Reticulocyte maturation parameters are reliable early predictors of hematopoietic engraftment after allogeneic stem cell transplantation.

Early detection of donor-derived hematopoietic restoration after allogeneic stem cell transplantation (allo-SCT) is a crucial issue in the management of heavily immunocompromised patients. The aim of this prospective study was to validate our previously defined cutoff values for reticulocyte maturation parameters as early predictors of hematopoietic engraftment. Importantly, the effect of clinical variables in reticulocyte engraftment was also sought. For this purpose, we prospectively studied 136 consecutive patients undergoing allo-SCT from related (n = 89) or unrelated (n = 47) donors. High fluorescence reticulocytes (RETH), immature reticulocyte fraction (IRF), mean fluorescence index (MFI), and mean reticulocyte volume (MRV) were automatically measured in peripheral blood samples drawn on a daily basis. We previously defined reticulocyte engraftment when MFI > or =10, RETH > or =3%, IRF > or =10%, and MRV > or =110 fL. Median neutrophil engraftment was 18 days (range, 10-35 days); for reticulocyte parameters, the values were 14 days for IRF (range, 7-45 days), 14 days for MFI (range, 7-43 days), 15 days for RETH (range, 7-43 days), and 21 days for MRV (range, 9-74 days). These differences reached statistical significance for MFI and IRF when compared with standard neutrophil recovery, even when analyzing siblings or unrelated donors separately. In univariate analysis, donor-recipient ABO disparity adversely influenced erythroid engraftment (P = .04 for IRF, P = .03 for MFI), but the infusion of >2.9 x 10(6)/kg of CD34+ cells was associated with a shorter time to reach erythroid engraftment (P = .02 for IRF and MFI). In Cox regression analysis, > or =100/microL neutrophils and IRF > or =10% were predictive parameters for standard neutrophil engraftment. Based on these findings, we suggest that serial measurement of IRF or MFI should be routinely used to trace hematopoietic restoration after allo-SCT because these preceded standard neutrophil recovery by a median of 4 days and are therefore very useful to make clinical decisions.     

自体分选造血干细胞和异体脐带间充质干细胞移植治疗神经系统变性疾病

背景：将自体分选造血干细胞和异体脐带间充质干细胞技术应用于临床,试图寻找一种新的治疗神经系统变性疾病的可行方法。 目的：探讨自体分选CD34⁺造血干细胞和异体脐带间充质干细胞治疗神经系统变性病的可行性。 方法：入选神经系统变性病患者21例,其中运动神经元病15例,脊髓小脑共济失调6例。取4 mL的脐带间充质干细胞或自体分选干细胞液经腰穿注射到患者蛛网膜下腔,每次注射的细胞数1.0×10⁷。于干细胞治疗后3个月进行评分。 结果与结论：15例运动神经元病患者,治疗总有效率为80%,治疗前后的脊髓侧索硬化功能分级量表和自我评估问卷评分差异有显著性意义(P < 0.05);6例脊髓小脑共济失调患者,按ICARS评分,4例病情等级下降,治疗总有效率为77%。21例中4例有轻度低颅压性头痛(腰穿后),14例采用脐带间充质干细胞治疗的患者中2例在治疗后2 h出现短暂发热,其余患者治疗后未见明显不良反应。结果初步表明自体分选造血干细胞和异体脐带间充质干细胞治疗神经系统变性病临床疗效肯定,安全可行。     

Effects of ABO incompatibility in allogeneic hematopoietic stem cell transplantation

IntroductionThe impact of ABO mismatch on outcomes following allo-HSCT remains controversial. In this study, our aim is to define the effect of ABO mismatch on post-transplant outcomes, engraftment kinetics and complications in a large cohort.Patients and methodsWe retrospectively identified 1000 patients who underwent allo-HSCT from either bone marrow or peripheral blood stem cells at our center between 1988 and 2016. P < 0.05 was considered statistically significant.ResultsFive hundred and ninety (59%) patient-donor pairs were ABO matched, 164 (16.4%) were ABO major mismatched (MM), 191 (19.1%) were ABO minor MM, and 55 (5.5%) were ABO bi-directionally MM. ABO matched pairs were more common in transplants from related donors (P < 0.001) and using bone marrow as a stem cell source (P < 0.001). In minor ABO MM transplantations, mild delayed hemolytic reaction occurred more frequently compared to major and bidirectional ABO MM transplantations (47% vs 35% and 18%, P < 0.001). Neutrophil engraftment was slightly delayed in ABO MM patient-donor pairs when compared ABO matched donor pairs according to median engraftment time in all group (167/410, 41% vs 204/590, 35%, P = 0.046). Pure red cell aplasia was diagnosed in 6 patients (1%). Higher risk of death was shown in ABO MM transplants compared to ABO matched transplants in overall survival (OS) analysis (HR:1.201, 95% CI:1.004–1.437, P = 0.045). The non-relapse mortality (P = 0.546) and cumulative incidences of acute graft versus host disease (aGVHD) and chronic (c) GVHD were comparable between ABO MM and ABO matched patient-donor pairs (for aGVHD, P = 0.235; for cGVHD, P = 0.137).ConclusionABO MM transplants were associated with decreased OS and slightly delayed neutrophil engraftment. NRM and the risk of GVHD were not related to ABO incompatibility.