供者CD4＋CD25＋CD127-调节性T细胞与儿童异基因造血干细胞移植后急性移植物抗宿主病相关研究

目的：探讨供体移植物CD4＋CD25＋CDl27-调节性T细胞（_rreg细胞）表达水平对儿童异基因造血干细胞移植（allo—HSCT）后急性移植物抗宿主病（aGVHD）的影响。方法：采用流式细胞术检测供体淋巴细胞中CD4＋CD25＋CDl27-Treg细胞比例,回顾性分析83例allo—HSCT患儿移植物Treg细胞与移植后aGVHD．其中50例恶性疾病．33例良性疾病。结果：83例患儿allo．HSCT均获造血重建,其中51例发生O～Ⅰ度aGVHD,32例发生Ⅱ-Ⅳ度aGVHD。发生0～Ⅰ度aGVHD与Ⅱ-Ⅳ度aGVHD患儿移植物Treg细胞比例有统计学差异（3．0％-＋0．8％比2．5％±1．O％,P=0．030）。中位随访时间286（69～496）d,50例恶性疾病患儿中8例复发,复发与非复发患儿移植物Treg细胞无显著差异（3．2％±0．8％比2．8％±0．8％,P=0．549）。结论：高水平供体移植物Treg细胞有助于降低儿童all0．HSCT后aGVHD发生率,且未增加移植后复发风险;移植物Treg细胞表达量对预测aGVHD有一定意义。     

难治性白血病异基因骨髓移植后软组织肿瘤的危险因素及治疗的研究

难治性白血病的预后极差，目前惟一有望的治疗选择为异基因造血干细胞移植（allo—HSCT），可使20％-30％患者获得长期生存机会。复发是导致移植失败的主要原因之一。近两年来我们对17例急性白血病（AL）进行了allo—HSCT，其中6例为难治性或晚期白血病患者。6例中1例早期死亡为严重移植物抗宿主病（GVHD），4例先后发生髓外软组织肿瘤（EMD），1例无病生存。本研究着重描述了4例allo—HSCT后发生EMD患者的状况和治疗，并对EMD发生的危险因素及其治疗现状进行了文献综述。     

异基因造血干细胞移植患者血清抗HLA抗体检测的意义

目的研究血清抗HLA抗体与异基因造血干细胞移植（allo．HSCT）后移植物被排斥、疾病复发及移植物抗宿主病（GVHD）的关系。方法20例allo—HSCT患者在移植前与移植后1、3、6个月动态检测抗HLA抗体。结果移植前抗HLA抗体≥30％与〈30％的患者发生原发植入失败比较无显著性差异（P〉0．05）;在成功植入的17例患者中,移植前和（或）移植后抗HLA抗体I〉30％的5例患者均发生移植物被排斥或疾病复发,而抗HLA抗体均〈30％的12例患者中仅有1例发生,两者有显著性差异（P〈0．005）。移植后抗HLA抗体呈动态升高的3例患者均在植入后且抗HLA抗体〉130％时发生移植物被排斥和疾病复发,而呈动态降低的5例患者仅有1例在植入后发生移植物被排斥。移植前和（或）移植后抗HLA抗体≥30％的5例患者均未发生GVHD;而抗HLA抗体〈30％的12例患者中有9例发生急性和（或）慢性GVHD,发生率75％,两者有显著性差异（P〈0．005）。结论对allo．HSCT受者在移植前、后动态检测抗HLA抗体有助于预测移植物被排斥、疾病复发与GVHD的发生,抗HLA抗体〉130％或呈动态升高者继发植入失败或疾病复发的发生率高,而GVHD发生率较低。     

异基因造血干细胞移植术后移植物抗宿主病的研究进展

造血干细胞移植（HSCT）特别是异基因造血干细胞移植（allo—HSCT）越来越多地用于治疗恶性血液系统疾病,而移植后出现的移植物抗宿主病（GVHD）是allo-HSCT的主要并发症和死亡原因之一。移植物抗宿主病按发生时间分为急性移植物抗宿主病（aGVHD）和慢性移植物抗宿主病（cGVHD）。     

50例造血干细胞移植感染及经验性抗感染治疗分析

目的：探讨造血干细胞移植（HSCT）后感染的发生率、病原菌分布情况及经验性治疗方法。方法：对50例患者HSCT后感染及相应治疗的临床资料进行综合分析。结果：50例患者HSCT后，在ANC≥0．5×10^9／L前出现感染的有44例（88％），在ANC≥2．0×10^9／L前出现感染的有14例（28％）。采用我院选用的经验性治疗方案，即一线为碳青霉烯类单药或加用氨基糖甙类；二线选三代头孢菌素加用万古霉素；三线选了另一种碳青霉烯类加两性霉素B／伊曲康唑治疗。最终仅有3例患者因同时并发有重度移植物抗宿主病或植入失败导致的特殊感染而死亡。结论：我院采用的抗感染治疗的三线使用方案对于治疗HSCT后粒细胞缺乏／减少状态下发热患者是相当有效的。     

造血干细胞移植肝脏并发症临床研究

目的：总结造血干细胞移植（HSCT）后肝脏并发症的临床类型、病因、预后、及防治策略。方法：回顾性分析2001-2006年接受HSCT的279例血液病患者中肝脏并发症的病因、危险因素、及预后并着重分析肝静脉闭塞病（HVOD）患者的临床表现、实验室检查、预后及危险因素。结果：279例HSCT患者中99例发生肝脏并发症（发生率35．48％）,其中23例发生HVOD（发生率8．24％）,62例发生涉及肝脏的移植物抗宿主病（GVHD）,其他14例包括药物性肝损害8例,戊型肝炎2例,活动性乙型肝炎2例,胆汁淤积性肝炎1例,肝真菌病1例。截止随访结束死亡36例。23例HVOD患者,9例于移植后100d内死亡,其中7例死于HVOD引起的多脏器功能衰竭（MOF）（63．6％）。经统计学分析HSCT后肝脏并发症的危险因素有异基因造血干细胞移植（allo—HSCT）,无关供者（UD）移植,移植前有肝炎病毒感染,肝功能异常及并发真菌感染。患肝脏并发症的HSCT患者的总生存率明显低于其他组。结论：肝脏并发症是HSCT后降低患者总生存时间的一重要因素。其中HVOD尤为严重且危险。HVOD的预防,控制肝炎病毒感染以及针对肝脏并发症高危因素筛选高危患者选择适当预处理及GVHD预防方案,有助于降低肝脏并发症的发生率,降低HSCT患者移植后的死亡率。     

异基因造血干细胞移植后肾脏病变3例临床分析

目的探讨异基因外周血造血干细胞移植（HSCT）后肾脏病变的诊断与治疗。方法对3例异基因造血干细胞移植相关肾脏病变患者的诊治情况进行分析。结果 3例患者肾脏病变的原因分别为药物损害、白血病复发合并严重感染、慢性移植物抗宿主病膜性肾病。例1调整免疫抑制剂、例3联合应用免疫抑制剂骁悉及甲基泼尼松龙,分别无病存活36、23个月;例2治疗无效死亡。结论 HSCT患者出现蛋白尿等肾脏病变时,应及时明确发病原因,采用相应的诊疗措施,必要时应及时进行肾穿刺活检;联合应用免疫抑制剂疗效较好。     

异基因造血干细胞移植治疗高危恶性血液病

目的 分析HLA配型相合同胞供者异基因造血干细胞移植（allo-HSCT）治疗高危恶性血液病的疗效及影响疗效的相关因素。方法 回顾性分析90例有高危因素的恶性血液病患者,其中急性髓细胞白血病（AML）43例,急性淋巴细胞性白血病（ALL）28例,急性混合细胞性白血病（AHL）2例;移植前处于第1次完全缓解期（CR1）11例,均为Ph染色体阳性,第二次及以上CR期23例,未缓解／复发39例;骨髓增生异常综合征（MDS）-难治性贫血伴原始细胞增多或难治性贫血伴原始细胞增多一转化型17例。预处理方案采用全身照射加环磷酰胺（CY／TBI）方案11例,白消安加环磷酰胺方案79例。干细胞来源包括骨髓移植（BMT）27例,外周血造血干细胞移植（PBSCT）30例,BMT＋PBSCT33例;移植物抗宿主病（GVHD）预防采用经典环孢素A加短程甲氨蝶呤（MTX）。平均随访时间为15个月。结果 至随访终点,62．2％（56／90）存活,55．5％（50／90）无病存活,31．1％（28／90）复发。HSCT后预计4年累积总体生存率（OS）为45．5％,无病生存率（DFS）为34．9％。移植前处于CR、未缓解／复发和MDS患者HSCT后4年的累积0s分别为54．0％、28．2％和70．1％（P=0．027）。发生0～Ⅰ和Ⅱ～Ⅳ度GVHD的患者HSCT后的4年OS分别为57．6％和26．7％（P=0．015）,而患者性别、年龄、移植前有无脑膜白血病、预处理方案、干细胞来源均不是OS,DFS及复发的影响因素。多因素分析表明,移植前处于CR期者长期生存率明显提高,而ALL长期生存率明显低于AML／MDS。结论 对有高危因素的血液系统恶性肿瘤患者,选择allo—HSCT可使部分患者延长无病生存乃至根治。移植前处于CR期者长期生存率明显提高,ALL复发率明显高于AML／MDS。对于急性白血病挽救性治疗争取在取得CR后移植;对于MDS患者一经诊断,无需化疗,可尽早移植。     

非去T细胞单倍型相合的造血干细胞移植31例临床分析

目的 探讨HLA单倍型相合造血干细胞移植（HSCT）对恶性血液病的疗效及其预后。方法 总结2002年7月至2006年7月在我院治疗的31例恶性血液病患者（标危组11例,高危组20例）接受HLA单倍型相合HSCT临床资料,分析急性移植物抗宿主病（aGVHD）发生及其相关因素。结果 31例患者中30例获得稳定的造血重建,移植后中性粒细胞〉0．5×10^9／L及血小板〉20×10^9／L的中位时间分别为13d和22d,发生Ⅱ-Ⅳ度aGVHD的累积发生率为61．3％,慢性GVHD的累积发生率为41．9％。标危组33个月累积无病生存率（DFS）为62．3％,高危组33个月的DFS为35．0％。移植物中CD3^＋T细胞数量和供受体HLA—A、B、DR位点不相合的程度是影响aGVHD发生的主要因素。结论 HLA单倍型相合的HSCT对于恶性血液病是一种有效的治疗方法,移植物中CD3^＋T细胞数量和HLA—A、B、DR位点不相合的程度是影响单倍型相合的HSCT的aGVHD发生的主要因素。     

异基因造血干细胞移植治疗高龄恶性血液病的疗效分析

目的探讨异基因造血干细胞移植治疗年龄较大的白血病患者安全性和疗效。方法采用HSCT治疗10例45—63岁恶性血液病患者,HLA6／6位点相合8例,5／6位点相合2例。以清髓性方案预处理4例,减低强度方案预处理6例。HLA不全相合患者加用ATG。采用环孢素联合霉酚酸酯预防移植物抗宿主病（GVHD）。结果本组10例受者均获造血重建。中性粒细胞绝对计数≥0．5×10^9／L,血小板≥20×10^9／L的中位时间分别为移植后12（9～16）天和15（12～21）天。3例发生了急性GVHD（30％）,Ⅱ度以上2例。可评估的9例患者中2例出现了慢性GVHD（22％）。复发2例,死亡3例。可评估的2年无病生存率为70％。结论造血干细胞移植对于高龄白血病患者是一种有效、安全的根治疗法。     

Extramedullary vs medullary relapse after autologous or allogeneic hematopoietic stem cell transplantation (HSCT) in multiple myeloma (MM) and its correlation to clinical outcome

Risk-adapted treatment of multiple myeloma (MM) includes autologous (auto-) and allogeneic (allo-) hematopoietic stem cell transplantation (HSCT). Case reports on extramedullary (EM) compared to bone marrow (BM) relapse after HSCT suggest a dismal prognosis. We compared the outcome of 78 MM patients relapsing after auto- (group A: n = 53) or allo- (group B: n = 25) HSCT, stratified into BM (64 patients) vs EM (14 patients) relapse. The relapse-specific groups were also compared with respect to risk factors, including age, beta2-microglobulin, pretreatment, cytogenetics and stage. EM relapse sites were lungs (5), soft tissue (4), pericardium (2), bone (1), skin (1) and CNS (1). As of May 2004, the overall (OS) and progression-free (PFS) survival after HSCT in patients relapsing from EM sites was not significantly different from BM relapse patients, both after auto- and allo-HSCT. Although MM patients relapsing from EM sites after allo-HSCT used to be regarded as having few therapeutic options, we observed encouraging responses to donor lymphocyte infusions (DLI). Treatment responses to DLIs were observed in 5/9 (56%) BM relapse patients, and in 3/4 (75%) EM relapse patients. These observations suggest that EM relapse after HSCT is common and needs an individualized diagnostic and therapeutic approach in MM during clinical follow-up after HSCT.     

Occurrence of Pneumocystis jiroveci pneumonia after allogeneic stem cell transplantation: a 6-year retrospective study

Pneumocystis jiroveci pneumonia (PCP) has become a rare opportunistic infection due to the efficacy of prophylactic regimens. We conducted a 6-year retrospective study at our institution. A total of 13 cases of PCP were diagnosed among 519 patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) (2.5%). In three patients, PCP occurred within the first 5 months following HSCT. These severely immunocompromised patients were receiving prophylaxis and had concomitant aspergillosis that caused rapid death in two of them. In 10 other patients, PCP occurred a median of 14.5 months after HSCT. In all these patients, PCP prophylaxis had been discontinued, mainly because of the suspected bone-marrow toxicity of the prophylactic regimen. Median CD4+ T cell count was 131/microl at diagnosis. Seven of these 10 patients were receiving immunosuppressive therapy for chronic graft versus host disease and three had a relapse of their hematological malignancy. One patient died from PCP despite high doses of cotrimoxazole. We conclude that PCP is still occurring after allogeneic HSCT, mainly as a late complication in patients in whom PCP prophylaxis had been prematurely discontinued. Long-term PCP prophylaxis should be maintained in patients receiving immunosuppressive drugs, and in those with low CD4+ T cell counts or a relapse of their hematological malignancy.     

血液系统恶性疾病异基因造血干细胞移植后WT1基因动态检测的意义

目的 初步探索在各类血液系统恶性疾病异基因造血干细胞移植(allo-HSCT)后,动态检测WT1基因表达水平对监测微小残留病(MRD)及预测临床复发的意义.方法 采用实时定量(RQ)-RT-PCR技术动态检测31例allo-HSCT后患者的WT1基因表达(共计102份骨髓标本),测定其WT1 mRNA及内参基因ABL mRNA拷贝数.结果 复发组和未复发组WT1基因中位表达水平分别为0.80%、0.17%,两者间差异有统计学意义(P<0.01).动态检测复发组WT1基因表达,显示WT1基因表达在临床复发前或伴随临床复发时可有明显的升高(均>1.0%),复发时WT1基因表达水平较复发前一次明显升高(P<0.05).结论 应用RQ-RT-PCR技术动态检测WT1基因表达,可能是移植后监测MRD及预测复发的一种有希望的手段.     

HBsAg阳性患者异基因造血干细胞移植后的临床研究

目的 探讨HBsAg阳性患者接受异基因造血干细胞移植(allo-HSCT)后的肝脏不良事件的发生及影响该类患者长期存在的危险因素.方法 回顾性分析本所2001年3月至2006年11月接受allo-HSCT治疗的26例HBsAg阳性患者的临床资料.造血干细胞来源:18例为HLA配型相合同胞,7例为HLA配型不合亲缘供者,1例为无关供者.所有患者移植前后均排除丙型肝炎病毒感染.2例移植前HBV DNA阳性,其余均表达阴性.结果 26例患者急性移植物抗宿主病(Agvhd)累积发生率为50.0%.在可评估的20例中,5例发生了慢性GVHD,累积发生率25.0%.移植后出现肝功能异常共有15例(57.7%).出现肝功能受损的病因主要为:乙型肝炎及肝脏GVHD.移植后乙型肝炎再燃5年累积发生率33.4%,发生中位时间为82(65～159)d.拉米夫定预防性应用13例,1例发生乙型肝炎事件;未给药组为11例,7例发生乙型肝炎事件,两者累积发生率差异有统计学意义(P=0.006);预防用药组未发生一例肝衰竭,未预防用药组发生4例肝衰竭.死亡原因:5例肝衰竭,3例肺部感染,2例移植后疾病复发.26例患者中共有10例死亡,5年生存率(OS)为59.0%.多因素分析最终确定与OS发生相关的危险因素为肝衰竭(P=0.000).结论 HBsAg阳性患者接受allo-HSCT治疗后常出现肝功能异常表现,其首要病因为乙型肝炎,所导致的肝衰竭严重影响患者预后.而对HBsAg阳性患者预防性应用拉米夫定能够有效预防移植后乙型肝炎的复燃.     

The influence of diagnostic bronchoscopy on clinical outcomes comparing adult autologous and allogeneic bone marrow transplant patients

STUDY OBJECTIVES: To review our experience with diagnostic bronchoscopy in the evaluation of pulmonary infiltrates in adult hematopoietic stem cell transplantation (HSCT) recipients in the era of Pneumocystis prophylaxis and cytomegalovirus antigen testing. The study focused on diagnostic yields and the influence of bronchoscopic findings on pharmacologic therapy and mortality, comparing allogeneic (allo) HSCT patients to autologous (auto) HSCT patients. DESIGN: Case series review. SETTING: Tertiary care academic urban medical centers. PATIENTS: All adult allo-HSCT and auto-HSCT patients undergoing bronchoscopy for the evaluation of pulmonary infiltrates from January 1997 to September 2001. MEASUREMENTS AND RESULTS: The review identified 169 bronchoscopies that had been performed on HSCT patients, representing 12.5% of all HSCT patients (allo-HSCT patients, 125 bronchoscopies; auto-HSCT patients, 44 bronchoscopies). Bronchoscopy was requested more often in allo-HSCT patients (18.7%) compared to auto-HSCT patients (6.6%). Findings at bronchoscopy provided a specific diagnosis more frequently in allo-HSCT patients (50%) compared to auto-HSCT patients (34%). For both allo-HSCT and auto-HSCT patients, most diagnoses were obtained by BAL alone, whereas transbronchial biopsy (TBBx) provided additional specific information in < 10% of cases. For select patients (n = 27), surgical lung biopsy following bronchoscopy provided unique diagnoses in 47 to 50% of cases. Information from bronchoscopy influenced clinical decisions more often in allo-HSCT patients (50%) than in auto-HSCT patients (36%), and allowed for the discontinuation or addition of antimicrobial, corticosteroid, or antineoplastic agents to treatment. Complications from bronchoscopy occurred in 9% of all HSCT patients (n = 15), and were associated with higher in-hospital mortality rates in allo-HSCT patients (82%; n = 9) compared to auto-HSCT patients (50%; n = 2). The overall in-hospital mortality rates for allo-HSCT and auto-HSCT patients having bronchoscopy was similar (38% vs 27%, respectively; p = 0.25), and establishing a specific diagnosis by bronchoscopy did not improve the in-hospital mortality rate for allo-HSCT or auto-HSCT patients. CONCLUSIONS: Bronchoscopy may provide clinically useful information in the evaluation of adult allo-HSCT and auto-HSCT recipients with pulmonary infiltrates. The results of testing BAL fluid samples alone suggested an etiology in most cases, whereas the findings of TBBx provided unique diagnoses infrequently. Further studies are warranted to improve the utility of diagnostic bronchoscopy in the evaluation of HSCT patients.     

异基因造血干细胞移植治疗白血病76例临床观察

目的观察不同来源的异基因造血干细胞移植治疗白血病的疗效并探讨主要并发症的处理方案。方法对2001年9月至2007年3月第四军医大学西京医院血液科76例白血病患者行异基因造血干细胞移植治疗,其中慢性粒细胞白血病34例,急性髓性白血病24例,急性淋巴细胞白血病15例,T细胞淋巴瘤/白血病3例。人类白细胞抗原(HLA)全相合的同胞供者57例,1个HLA位点不合同胞供者3例,HLA单倍型半相合同胞供者7例,非血缘供者9例。预处理方案采用改良的马利兰联合环磷酰胺(BUCY)或改良的环磷酰胺联合全身放疗及阿糖胞苷或鬼臼乙叉甙(CyTBI Ara-c/VP-16)方案。采用标准的环孢素A(CsA)联合短期甲氨蝶呤(MTX)方案预防移植物抗宿主病(GVHD);无关供者移植加用抗人胸腺细胞球蛋白,单倍型半相合移植同时加用CD25单克隆抗体。结果96.1%(73/76)获得植入。24.7%(18/73)出现急性GVHD,32.9%(24/73)出现慢性GVHD;合并重症肝静脉闭塞病2例;并发纯红细胞性再生障碍性贫血5例。随访3~72个月,现存活56.6%(43/76),43.4%(33/76)在移植后1~36个月时死亡,19例死于白血病复发,14例死于移植相关并发症。结论多种来源的异基因造血干细胞移植是治疗白血病的有效方法,于慢性粒细胞白血病慢性期、急性白血病缓解期移植效果较好,移植前处于高危难治状态的病例复发率仍较高。     

Allogeneic hematopoietic stem cell transplantation with fludarabine, melphalan, and total body irradiation as a conditioning for elderly patients with myeloid malignancies

A variety of reduced-intensity conditionings have been used in the reported studies of allogeneic hematopoietic stem cell transplantation (HSCT) for elderly patients with myeloid hematological malignancies. This study retrospectively analyzed the outcome of allogeneic HSCT for 10 patients aged 50 years or older with myeloid hematological malignancies after conditioning with fludarabine (125 mg/m(2)), melphalan (140 mg/m(2)) and total body irradiation (TBI; 8 Gy). Median age of the patients was 56.5 years, and diagnoses included acute myelogenous leukemia, advance myelodysplastic syndrome, and secondary myelofibrosis. Sources of stem cells were bone marrow from sibling (n=4) or unrelated donor (n=6). Both overall and disease-free survival rates were 40.0% (95% CI: 10.6~69.4%). Causes of death were relapse (n=2), fungal infection (n=2), and secondary malignancies (n=2). Because of a high incidence of transplant-related mortality, further refinement of this conditioning is required.     

165例急性白血病死亡原因回顾

目的:分析探讨165例急性白血病(非M3)的死因。方法:回顾165例急性白血病(非M3)死亡病例,总结急性白血病主要死亡原因及死亡时的疾病状态。结果:116例急性非淋巴细胞性白血病(非M3)的主要死因为感染(45.7%)和出血(28.4%),其次为中枢神经系统(8.6%)和肺部弥漫性损害(6.9%),44.0%病例死于疾病的复发阶段,28.4%在发病早期,25.0%在未缓解期内,仅2.6%死于完全缓解阶段。49例急性淋巴细胞性白血病的主要死因为感染(34.7%)、出血(30.6%)和浸润(26.5%),最常见的感染形式为败血症,出血和浸润最易累及的部位分别为颅内和中枢神经系统,多数病例死于疾病的早期(45.0%)和复发阶段(51.0%)。结论:感染、出血和浸润是急性白血病(非M3)的三大主要死因。     

异基因造血干细胞移植治疗Fms样酪氨酸激酶3基因内部串联重复(FLT3-ITD)阳性的急性髓性白血病的疗效分析

 目的 分析异基因造血干细胞移植(allo-HSCT)治疗伴有Fms样酪氨酸激酶3基因内部串联重复(FLT3-ITD)阳性的急性髓性白血病(AML)的疗效,探讨不同移植方式及疾病状态对该类患者预后的影响。方法 2006年10月至2012年10月在苏州大学附属第一医院行allo-HSCT的AML患者共314例,其中FLT3-ITD阳性54例,回顾性分析allo-HSCT对FLT3-ITD阳性AML患者的临床疗效。结果 54例FLT3-ITD阳性患者3年总生存(OS)率为56%, 3年无白血病生存(LFS)率为47%。其中同胞人类白细胞抗原(HLA)全相合及亲缘HLA单倍型相合造血干细胞移植的患者3年OS率分别为56%和60%,3年LFS率为45%和54%。两组在OS时间及LFS时间方面的差异均无统计学意义(χ²=0.074,P=0.786; χ²=0.006,P=0.941)。47例(87.0%)患者移植前本病处于首次完全缓解(CR1),7例(13.0%)患者移植前本病处于非CR1期。处于CR1期的患者的生存显著优于非CR1期患者。结论 allo-HSCT是FLT3-ITD阳性AML患者的有效治疗方法,亲缘HLA单倍型相合造血干细胞移植与同胞HLA全相合移植疗效相似。疾病复发是影响其疗效的主要因素。
        

Analysis of chimerism in patients with hematologic malignancies after allogeneic hematopoietic stem cell transplantation

Serial monitoring of chimerism after allogeneic hematopoietic stem cell transplantation (HSCT) can be performed easily and rapidly using PCR-based assays analyzing informative tandem repeat genetic markers. Sequential analysis of individual chimerism status was performed in 34 patients who underwent myeloablative allo-HSCT using a commercial multiplex short tandem repeat (STR) kit. Mixed chimerism (MC) was found in 14 of the patients for more than one month. The incidence of MC seemed to be dependent on the type of disease or pretransplantation regimen. There was no significant difference in relapse rates between MC and complete donor chimerism (CC) in all patients. However, the relapse rate was significantly higher in MC than in CC among patients with acute leukemia. The severity of acute graft-versus-host disease (aGVHD) was significantly reduced in the patients with MC. Most of the MC patients with hematologic malignancies had transient mixed T-lymphoid chimerism, and CC was achieved within 6 months after HSCT in such cases. Patients with MC beyond 6 months after HSCT and patients with reappearance of autologous signals (MC after CC) may have an enhanced risk of relapse.