Harnessing and honing mesenchymal stem/stromal cells for the amelioration of graft-versus-host disease

Allogeneic hematopoietic stem cell transplantation is a deterministic curative procedure for various hematologic disorders and congenital immunodeficiency.Despite its increased use,the mortality rate for patients undergoing this procedure remains high,mainly due to the perceived risk of exacerbating graft-versushost disease(GVHD).However,even with immunosuppressive agents,some patients still develop GVHD.Advanced mesenchymal stem/stromal cell(MSC)strategies have been proposed to achieve better therapeutic outcomes,given their immunosuppressive potential.However,the efficacy and trial designs have varied among the studies,and some research findings appear contradictory due to the challenges in characterizing the in vivo effects of MSCs.This review aims to provide real insights into this clinical entity,emphasizing diagnostic,and therapeutic considerations and generating pathophysiology hypotheses to identify research avenues.The indications and timing for the clinical application of MSCs are still subject to debate.

Pathophysiology of acute graft-versus-host disease from the perspective of hemodynamics determined by dielectric analysis

BACKGROUND Numerous reports have demonstrated that the pathophysiology of graft-versushost disease(GVHD)during hematopoietic stem cell transplantation(HSCT)is closely related to vascular endothelial disorders and coagulation abnormalities.We previously presented the discovery of a principle and the development of a novel instrument for measuring whole blood coagulation.This was achieved by assessing the variations in the dielectric properties of whole blood.AIM To investigate how GVHD affects the changes of dielectric properties of whole blood in patients with HSCT.METHODS We examined the changes of dielectric properties of whole blood and erythrocyte proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis sequentially in patients with HSCT and compared it with clinical symptoms and inflammatory parameters of GVHD.RESULTS During severe GVHD,the dielectric relaxation strength markedly increased and expression of band3 decreased.The dielectric relaxation strength normalized with the improvement of GVHD.In vitro analysis confirmed that the increase of relaxation strength was associated with severe erythrocyte aggregates,but not with decreased expression of band3.CONCLUSION Severe erythrocyte aggregates observed in GVHD may cause coagulation abnormalities and circulatory failure,which,together with the irreversible erythrocyte dysfunction we recently reported,could lead to organ failure.

Cytokines are early diagnostic biomarkers of graft-versus-host disease in liver recipients

BACKGROUND： Graft-versus-host disease （GVHD） is associated with high mortality. Early diagnosis is essential to start treatment and to improve outcomes. Because of the inflammatory nature, we hypothesis that cytokine profile of patients with GVHD may serve as diagnostic markers. The present study was to evaluate the role of cytokine profile in the diagnosis of GVHD. METHODS： An immunoassay was used to detect 29 cytokines simultaneously in the serum; the measuring sensitivity of all cytokines was pg/mL. Healthy subjects undergoing annual routine physical examinations served as negative controls; 23 patients with hepatocellular carcinoma （HCC） who had undergone liver transplantation （the LT group） comprised the test subjects. A total of 22 kidney recipients with biopsyconfirmed GVHD （the RT group） were included for comparison. HCC patients with radical surgery （the HCC group, n=22） served as positive control. The liver contents of the three cytokines, IL-2, IL-18, and IFN-γ, were detected with immunohistochemistry. Serum granzyme B and perforin were measured by flow cytometry.RESULTS： Of the 29 cytokines, the levels of IL-2 and IL-18 were increased significantly in liver recipients with GVHD compared with healthy controls （P〈0.05）. The serum levels of these three cytokines in the healthy, HCC, LT, and RT groups were IL-2： 0.90±0.02, 4.14±0.61, 5.10±0.89, and 1.48±0.09 pg/mL; IL-18： 80.61±9.35, 109.51±10.93, 230.11±12.92, and 61.98±7.88 pg/mL; IFN-γ： 24.06±3.88, 24.84±3.21, 40.37±5.88, and 15.33±4.72 pg/mL, respectively. Immunohistochemistry showed that these 3 cytokines expressions in the liver were parallel to the serum cytokine. After standard anti-GVHD treatment, the expressions of IL-2, IL-18, and IFN-y were de- creased in the liver （P〈0.05）. Serum granzyme B and perforin were significantly increased in GVHD patients （P〈0.05）. CONCLUSIONS： IL-2, IL-18 and IFN-γ were from liver and might serve as biomarkers for monitoring GVHD develop- ment and the effects of anti-GVHD treatment. Granzyme B and perforin may play a role in increasing IL-2, IL-18, and IFN-y levels in GVHD patients.

Fulminant gastrointestinal graft-versus-host disease concomitant with cytomegalovirus infection:Case report and literature review

Here,we report a case of fulminant gastrointestinal graft-versus-host disease(GI-GVHD) with cytomegalovirus(CMV) infection in 44-year-old woman.Despite the difficulties associated with the treatment of GIGVHD and GI-CMV disease,the mucosal findings and the clinical course showed marked improvements during long-term clinical observation.The endoscopic findings were remarkable,with diffuse sloughing mucosa in the stomach and highly active inflammation and deep discrete ulcers throughout the colon.Changes in the CMV quantitative polymerase chain reaction results were correlated with the endoscopic mucosal findings and were useful for assessing the efficacy of the treatment.Although a definite diagnosis of GI-GVHD is generally made by endoscopy with biopsy,the gross appearance of this disease can vary depending on the endoscopy.In this paper,we also conduct a literature review of patients with GI-GVHD.

Umbilical Cord Blood-derived Mesenchymal Stem Cells Ameliorate Graft-Versus-Host Disease Following Allogeneic Hematopoietic Stem Cell Transplantation through Multiple Immunoregulations

Summary： Although mesenchymal stem cells （MSCs） are increasingly used to treat graft-versus-host disease （GVHD）, their immune regulatory mechanism in the process is elusive. The present study aimed to investigate the curative effect of third-party umbilical cord blood-derived human MSCs （UCB-hMSCs） on GVHD patients after allogeneic hematopoietic stem cell transplantation （allo-HSCT） and their immune regulatory mechanism. Twenty-four refractory GVHD patients after allo-HSCT were treated with UCB-hMSCs. Immune cells including T lymphocyte subsets, NK ceils, Treg cells and dendritic cells （DCs） and cytokines including interleukin-17 （IL-17） and tumor necrosis factor-alpha （TNF-α） were monitored before and after MSCs transfusion. The results showed that the symptoms of GVHD were alleviated significantly without increased relapse of primary disease and transplant-related complications after MSCs transfusion. The number of CD3^＋, CD3＋CD4^＋ and CD3＋CD8^＋ cells decreased significantly, and that of NK cells remained unchanged, whereas the number of CD4^＋ and CD8^＋ Tregs increased and reached a peak at 4 weeks; the number of mature DCs, and the levels of TNF-α and IL-17 decreased and reached a trough at 2 weeks. It was concluded that MSCs ameliorate GVHD and spare GVL effect via immunoregulations.

Comparison of the meibomian gland dysfunction in patients with chronic ocular graft-versus-host disease and Sjogren's syndrome

AIM: To investigate the abnormalities in the meibomian gland in patients with dry eye disease(DED) associated with chronic ocular graft-versus-host disease(coGVHD) in comparison with Sj?gren's syndrome(SS), a major form of aqueous deficient DED and meibomian gland dysfunction(MGD), a common cause of evaporative DED.METHODS: A total 135 eyes of 135 subjects included in this study: patients with DED associated with coGVHD(n=30), patients with SS(n=35), patients with MGD(n=35), and normal controls(n=35). All participants completed the Ocular Surface Disease Index(OSDI) questionnaire, ocular surface examination [Schirmer test, tear film breakup time(TFBUT), and ocular surface staining], and meibomian gland assessment [meiboscore(gland dropout detected on meibography using infrared camera of the Keratograph 5 M), meibum expressibility score(MES), meibum quality score(MQS), lid margin abnormality]. In addition, correlations of meibomian gland characteristics with ocular surface parameters as well as disease severity score were investigated in coGVHD group.RESULTS: The coGVHD group showed significantly higher meiboscore, MES, and MQS than the other 3 groups(all P<0.05). In the coGVHD group, parameters of meibomian gland showed a significant correlation each other and those of ocular surface. The correlation between meibomian gland parameters and severity score of co GVHD was also established(meiboscore, r=0.62; MES, r=0.47; MQS, r=0.47; lid margin abnormality score, r=0.55; all P<0.05).CONCLUSION: Patients with DED associated with co GVHD show poorer gland morphology and worse glandfunction than other types of DED. In addition, meibomian gland damage is not only associated with ocular surface damage but also disease severity of coGVHD.

Diagnosis and treatment of acute graft-versus-host disease after liver transplantation:Report of six cases

BACKGROUND Graft-versus-host disease(GVHD)following liver transplantation(LT)is an unpredictable complication with poor outcome.However,consensus regarding the diagnosis and therapeutic regimen for the disease is yet lacking.The present study summarized the clinical experience on the diagnosis and treatment of acute GVHD(aGVHD)following LT and reviewed the pertinent literature.CASE SUMMARY Between January 1^(st),2000 and December 31^(st),2020,a total of 1053 LT were performed in the First Affiliated Hospital of Xi’an Jiaotong University.Six recipients developed aGVHD with clinical symptoms of fever,rash,diarrhea,and pancytopenia.The incidence of aGVHD was 0.57%.The median time from LT to the clinical presentation of aGVHD was 22.17 d.The median time from the beginning of the clinical symptom to histopathological diagnosis was 7.5 d.All six cases underwent treatment of immunosuppressant adjustment,corticosteroids,human normal immunoglobulin,and antithymocyte globulin/IL-2 antagonists.Despite intensive treatment strategies,4 patients were deceased due to sepsis,multiple organ failure,and cerebral hemorrhage.The remaining two cases were discharged as treatment successfully.However,one died because of tuberculosis infection on the 6 th month of follow-up,the other one was alive healthy during 30 mo of follow-up.CONCLUSION The rapid diagnosis of aGVHD is mainly based on the time from the first symptom,histopathological features,and the donor T-lymphocyte chimerism.Our cases report highlights massive corticosteroid therapy and age difference between donors and recipients could accelerate to aGVHD.Moreover,gut microbial interventions and donor-targeted serotherapy may provide novel therapeutics.

Immune Regulatory Cell Biology and Clinical Applications to Prevent or Treat Acute Graft-Versus-Host Disease

The most common approaches to prevent and treat graft-versus-host disease (GVHD) are intended to deplete or suppress the T cells capable of mediating or supporting alloresponses;however, this renders the recipients functionally T cell deficient and hence highly susceptible to infections and tumor recurrence. Depletion is often accomplished through the use of broadly reactive antibodies, while functional impairment is typically achieved by pharmacological agents that require long-term administration (usually six months or more), have significant side effects, and may not result in tolerance (i.e., nonresponsiveness) of donor T cells to conditioning regimen-resistant host alloantigen-bearing cells. As our knowledge of immune system homeostasis has increased, cell populations with immune regulatory function have been identified and characterized. Although such cell populations are typically present in low frequencies, methods to isolate and expand these cells have permitted their supplementation to the donor graft or infusion late post-transplant in order to stifle GVHD. This review discusses the biology and preclinical proof of concept of GVHD models, along with GVHD outcomes that focus exclusively on immune regulatory cell therapies that have progressed to clinical testing.

Nanoparticle-encapsulated allogeneic T cells mitigate graft-versus-host disease but retain graft-versus-leukemia activity

Aim Allogeneic hematopoietic stem cell transplantation （HSCT） has curable potential for hematopoietic malignancies through graft-versus-leukemia （GVL） effects but is often associated with life-threatening graft-versus-host disease （GVHD）. Donor T cells play an important role in the pathological process of GVHD. In this study, to determinate immunoisolation through encapsulating T cells with biomaterials could be a promising approach to atten- uate GVHD. Methods T cells were isolated from spleens of donor C57B1/6 mice by magnetic cell separation and coated by layer-by-layer in chitosan and alginate. BALB/c recipient mice were established by GVHD mode and leukemia mode. Xenogen IVIS imaging system was used for live animal imaging. Donor BMCs and T cell subsets were analyzed by flow cytometry. Results In this study, we successfully encapsulated T cells of mice in multilay- ers of chitosan and alginate. In vitro studies showed that the encapsulation did not change the phenotype of T cells as defined through the following parameters： size, viability, proliferation, antibody binding, cytokine secretion, and cytotoxicity. Mice transplanted with encapsulated allogeneic T cells exhibited less severe acute GVHD and pro- longed survival. The mice showed a lower GVHD score, less liver damage, a smaller CD8/CD4 T cell ratio, and a higher number of donor BM-derived cells following transplantation with encapsulated donor T cells. When this GVHD model was combined with implantation of A20 lymphoma cells, GVL of encapsulated T cells was not com- promised, while GVHD was still suppressed and the mouse survival also prolonged. Conclusion These studies demonstrate that encapsulation of T cells with bio-degradable materials could attenuate the severity of GVHD but re- taine GVL, which presents a novel and potentially safer and effective approach of allogeneic HSCT for future clini- cal application.

Oral granuloma in a pediatric patient with chronic graft-versus-host disease:A case report

BACKGROUND Oral mucositis is often observed with graft-versus-host disease(GVHD);however,the occurrence of oral granuloma is rare.The rapid increase in granulomatous lesions should be distinguished from malignant tumors in patients with GVHD because malignant diseases can develop in those patients.This case is the youngest pediatric patient with granuloma associated with GVHD.CASE SUMMARY The patient was a 1-year and 5-mo-old girl who presented to our department for the management of oral nodules.At the age of 5 mo,she was diagnosed with primary immunodeficiency disease,cord blood transplant was performed at 11 mo and bone marrow transplant at 1 year of age.After transplantation,GVHD and oral mucositis developed,and tacrolimus was administered.Interestingly,nodules appeared on the lower lip and buccal mucosa,which spontaneously disappeared.Then,a new nodule appeared on the left lateral border of the tongue.Resection was performed and the histopathological diagnosis was granuloma.The origin of these nodules were considered to be the fibroblasts activated under inflammation caused by GVHD because the calcineurin inhibitor tacrolimus acted on their proliferation.CONCLUSION It is very important to distinguish oral granulomatous lesions from malignancies if GVHD is present at the base and if immunosuppressive agents and steroids are being administered.

Expressions of Tissue Factor and Tissue Factor Pathway Inhibitor in Patients with Acute Graft-versus-host Disease after Allogeneic Hematopoietic Stem Cell Transplantation

This study examined the expressions of human serum tissue factor （TF） and tissue factor pathway inhibitor （TFPI） in patients with acute graft-versus-host disease （aGVHD） after allogeneic hematopoietic stem cell transplantation （allo-HSCT） and their clinical significance. The serum TF and TFPI levels were detected by ELISA in 28 allo-HSCT recipients before and after the transplanta-tion and the changes of TF and TFPI levels were dynamically monitored at different phases of the disease. No significant differences in the serum TF and TFPI levels were found in allo-HSCT recipi-ents in the absence of aGVHD or with gradeⅠaGVHD before and after the transplantation. The lev-els of serum TF and TFPI were substantially increased in the patients with gradeⅡ aGVHD at the peak of aGVHD （P〈0.05） and they were even higher in the patients with grade Ⅲ–Ⅳ aGVHD （P〈0.01）. When the conditions became stable after treatment with immunosuppressive agents, the serum TFPI level was decreased to the baseline level （P〉0.05） and the TF level was lowered but still higher than the baseline level （P〈0.05）. It was concluded that the levels of serum TF and TFPI were increased significantly in the patients with grade Ⅱ–Ⅳ aGVHD after allo-HSCT and decreased markedly after the treatment. Monitoring the levels of serum TF and TFPI in the patients with allo-HSCT is important to predict the occurrence, outcome and prognosis of aGVHD.

Modified Vecchietti’s vaginoplasty with Remeex^(■) system in patient with chronic graft-versus-host disease

We present a case report of a chronic graft-versus-host disease manifestation in 33-year-old patient with an unusual complication of vaginal stenosis with complete obstruction after allogeneic bone marrow transplantation for myelocytic leukemia. The patient complained on a progressive dyspareunia and sexual intercourse inability. She has received hormone replacement therapy due to the ovarian failure after the chemotherapy treatment. The hormonal treatment was used in continuous combined manner and hematocolpos wasn’t seen during an abdominal ultrasound examination. The reconstructive surgery was performed by the modified Vecchietti’s neovagina technique with a Remeex&reg;system after histological confirmation of main diagnosis. The immediate postoperative course was uneventful with gradual normalization of sexual function.

OMISSION OF DAY +11 METHOTREXATE DOES NOT APPEAR TO INFLUENCE INCIDENCE AND SEVERITY OF GRAFT-VERSUS- HOST DISEASE AFTER ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANTATION

Objective: To explore the influence of omission of the day +11 dose of methotrexate (MIX) on the incidence and severity of graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Methods: From April 1997 to October 2002, 80 leukemia patients (46 men and 34 women aged from 12 to 56 years with a median age of 35) underwent allo-HSCT at our BMT unit. Among them, 58 patients received grafts from HLA-identical siblings, 8 from HLA one major antigen mismatched siblings and 14 from HLA-matched unrelated donors. All patients received a modified cyclosporine and short-course MTX regimen for GVHD prophylaxis, which included MTX 15 mg on day +1, and 10 mg on days +3 and +6 (MTX day +11 dose omitted) and cyclosporine given daily. Results: The overall incidence of grade I~IV acute GVHD was 57.5% (46/80 patients), with grade II~IV acute GVHD in 28 patients (35%) and grade III~IV acute GVHD in 7 patients (8.8%). Among 58 patients receiving grafts from HLA-identical siblings, 24 patients developed grade I~IV acute GVHD (41.4%), with grade II~IV acute GVHD in 13 patients (22.4%) and grade III~IV acute GVHD in 4 patients (6.9%). 2l out of 22 patients receiving grafts from HLA one major antigen mismatched siblings and HLA-matched unrelated donors developed grade I~IV acute GVHD (95.5%), with grade II~IV acute GVHD in 14 patients (63.6%) and grade III~IV acute GVHD in 3 patients (13.6%). Chronic GVHD occurred in 38 out of 56 evaluable patients (67.9%), with extensive form in 15 patients (26.8%) and limited form in 23 patients (41.1%). With a median follow-up of 960 days (range 180~1980 days), the probability of leukemia-free survival at 3 years was 61.3% for all patients. Conclusion: Our results suggest that the day +11 MTX can be omitted without a major deleterious effect on the incidence and severity of graft-versus-host disease after HLA-identical sibling transplantation as well as HLA one major antigen mismatched sibling and HLA-matched unrelated donor transplantation.

CT增强扫描鉴别异基因骨髓移植术后腹部GVHD和机遇性感染（英文）

目的:比较骨髓移植术后腹腔移植物抗宿主病(GVHD)和机遇性感染的CT表现以确定有助于鉴别诊断的CT特点。方法:纳入25例腹腔GVHD和15例腹腔机遇性感染患者,机遇性感染包括巨细胞病毒性感染(n=4)、真菌性感染(n=6)及细菌性感染(n=5)。对所有病人进行CT扫描。CT征象包括肠壁增厚、异常黏膜增强、肠管扩张、大量积液、胆管扩张、腹水以及邻近肠系膜条状征。分析病变的位置和范围。对两组病人的CT征象进行对照分析。结果:在胃肠道不连续性多发分布多见于GVHD;而连续性分布多见于机遇性感染(P<0.05)。胆管扩张是GVHD最常见的肠道外病变,然而非常少见于机遇性感染(P<0.05)。皮肤斑丘疹见于60%的GVHD,但是不见于机遇性感染(P<0.05)。对没有皮肤病变的病人,肠管病变的不连续分布和胆管扩张更多见于GVHD。结论:GVHD和机遇性感染的CT征象有较大重叠,尽管如此,一些临床和CT征象,例如皮肤斑丘疹、胆管扩张和肠管病变的不连续多发分布有利于诊断GVHD。

不完全相合造血干细胞移植中GVHD的预测研究:模拟HLA抗原结构的比较与应用

采用通用的微量淋巴细胞毒实验和序列测定方法对拟进行造血干细胞移植的患者及供体进行HLA分型 ;用计算机分子模拟手段 ,从HLA分子三维结构方面探讨预测移植物抗宿主病 (GVHD)发生程度 ,以预测移植后GVHD的发生情况。结果发现 ,8例供受体中 ,3例为半匹配移植 ,其中 2例发生了Ⅳ度GVHD ,1例发生了Ⅱ度GVHD ;3例为两个抗原不相合移植 ,其中 1例发生了Ⅱ度GVHD ,2例发生了Ⅱ度GVHD ;2例患者为一个抗原不相合移植 ,分别发生了Ⅰ度、Ⅱ度GVHD ;GVHD的发生程度与HLA不相合抗原RMSD差异的大小呈正相关。提示异基因造血干细胞移植时 ,GVHD发生程度与HLA分子三维结构的差异有密切关系 。

脂肪源间充质干细胞治疗aGVHD分子机制的初步研究

目的初步探讨成人脂肪源间充质干细胞(adultadiposetissue-derivedmesenchymalstemcells,AMSC)治疗急性移植物抗宿主病(acutegraft-versus-hostdisease,aGVHD)的分子机制。方法3例行异基因造血干细胞移植术后发生aGVHD患者,以每公斤体质量2×106个细胞剂量静脉输注AMSC;应用RT-PCR扩增患者AMSC使用前后外周血单个核细胞的TCRVβ24个亚家族的CDR3,了解患者TCRVβT细胞的分布情况;应用尼龙毛柱分离外周血T淋巴细胞再经CD8磁珠分选出CD8+T淋巴细胞,应用流式细胞术检测发生aGVHD患者使用AMSC前后外周血CD8+T细胞亚群的变化。结果患者发生aGVHD时,有TCRVβ3及其他亚家族基因表达,输注AMSC后,GVHD得以有效控制,Vβ不表达;当患者GVHD复发时,Vβ3基因又表达,治疗后不表达;与输注AMSC前相比,输注AMSC后,CD8+T细胞中的CD8+CD28-亚群显著上调(P<0.05),同时,患者的aGVHD得以有效控制。结论AMSC治疗aGVHD的分子机制可能与其抑制TCRVβ亚家族基因表达有关,TCRVβ3可能是AMSC作用的靶基因;同时,AMSC治疗aGVHD的作用机制可能与其上调CD8+CD28-T细胞亚群有关,CD8+T细胞可能是AMSC作用的靶细胞。

活化半相合混合骨髓移植GVHD反应的动物实验研究

目的:观察活化半相合混合骨髓移植的GVHD反应。方法:以急性放射病615小鼠模型为受鼠,615×C57BL/6杂交F1代小鼠为半相合供鼠。半相合鼠骨髓和脾细胞中混合一定比例的同基因脾细胞,经白细胞介素-2体外活化后,进行活化半相合混合骨髓移植。观察移植后小鼠死亡率、白细胞系造血重建、脾结节、体内混合淋巴细胞培养、嵌合体及病理学改变,比较不同移植方式的GVHD反应。结果:活化半相合骨髓移植组与未活化半相合骨髓移植组具有明显的GVHD反应。供受鼠3:1活化半相合混合骨髓移植不能明显降低GVHD反应,供受鼠脾细胞比例1:1和2:1移植组可以明显减轻GVHD反应。表现为外周血自细胞及骨髓造血恢复快,体内混合淋巴细胞反应降低及嵌合体百分率升高。结论:活化半相合混合骨髓移植方式可以降低GVHD反应,并与同基因和异基因脾细胞比例有关。

异基因骨髓移植后GVHD的皮肤病损组织学特点

本文介绍异基因骨髓移植后，移植物抗宿主病（ＧＶＨＤ）的皮肤病损组织学特点。通过病例的活检和尸检的皮肤病变，指出ＧＶＨＤ是以皮肤病损为特征，而且皮肤的症状出现最早，故皮肤活检确诊ＧＶＨＤ是十分重要的。认为表皮内出现木乃伊小体、淋巴细胞浸润及基底细胞变性、液化坏死，这三点是诊断ＧＶＨＤ皮肤病损的主要病理形态依据。同时，本文根据皮损特点提出有关ＧＶＨＤ诊断的注意点。

干细胞在自身免疫性疾病和GVHD的注册临床研究

近年来,干细胞治疗自身免疫性疾病和GVHD成为研究热点,为及时了解国内外干细胞治疗该类疾病的临床研究动态,为干细胞在这类疾病的临床研究提供参考信息。本文对近年来在美国NIH临床试验网站注册登记的相关临床研究进行简要综述。

Severe graft-versus-host disease post allogeneic hematopoietic stem cell transplantation due to loss of HLA heterozygosity in recipient lymphocytes after full graft rejection

Germ cell tumors complicated by hematological malignancy(HM)are a rare clinical phenomenon.Allogeneic hematopoietic stem cell transplantation(allo-HSCT)is a potentially effective therapy,but graft-versus-host disease(GVHD)is a life-threatening complication.We report a case of a 13-year-old female patient diagnosed with germ cell tumors followed by acute lymphoblastic leukemia.After chemotherapy,she received allo-HSCT and her chimerism rate decreased rapidly to near zero by 6 months without evidence of HM recurrence.However,she developed severe,multiorgan GVHD-like manifestations.DNA analysis revealed the pathogenesis of GVHD to be loss of HLA heterozygosity in recipient hematopoietic cells.