在小鼠异基因骨髓细胞移植中超抗原SEB诱导的耐受特征

目的:研究在异基因骨髓细胞移植中葡萄球菌肠毒素B(SEB)诱导的耐受强度和细胞学特征。方法:选用C57BL/J小鼠作为受体,BALB/c小鼠作为供体。所有受体小鼠在接受6×107骨髓细胞前均接受6.0Gy60Coγ射线的照射,随机分成3组:组1为只接受6.0Gy60Coγ射线照射的对照组(照射对照组,RI);组2为照射后注射生理盐水(移植对照组,Tran.);组3为照射后注射60μgSEB(SEB组)。180d后由组2和组3实验鼠获得两组C57BL/L-BALB/c嵌合体小鼠。用流式细胞术分析移植后30~180d受体小鼠体内CD4 T、CD8 T、CD3 /NK1.1 NKT淋巴细胞亚群的数量和MHCH-2Kb、H-2Kd抗原表达的百分率,用MLR方法测定嵌合体小鼠淋巴细胞对ConA和异源性抗原的反应性。结果:(1)接受大剂量骨髓细胞移植后,注射SEB和注射生理盐水的两组小鼠均可存活180d以上,SEB组小鼠呈现出BALB/c供体小鼠的颜色特征(白色);Tran.组小鼠呈现出其灰白色。(2)SEB组嵌合体小鼠对ConA的反应性明显低于RI组和Tran.组;对异源性抗原的应答高于Tran.组。(3)SEB组小鼠外周血中CD4 T细胞的数量在移植后30~60d明显下降,随后增加;CD8 T细胞的数量不变。CD3 /NK1.1 NKT细胞的数量,从接受移植后30d开始增加,随着时间的延长而递增,到180d达到5.71%。存活180d的嵌合体小鼠,体内供体小鼠特有的MHCH-2Kd抗原的表达率高达80.95%,自体MHCH-2Kb抗原表达的百分率只占1.45%。(4)与SEB组相反,Tran.组小鼠CD8 T细胞的数量持续下降;CD3 /NK1.1 NKT细胞的数量的增加只在移植后180d上升达到5.07%。结论:在异基因骨髓细胞移植中,SEB诱导的耐受性比单纯骨髓移植诱导的耐受性强。SEB诱导的耐受性与移植早期特异性CD4 T细胞数量的减少和NKT细胞数的持续增加有关。反应性的降低表现为T细胞对ConA反应性的下降。     

髓腔内骨髓移植诱导异基因小鼠皮肤移植耐受的研究

探讨髓腔内骨髓移植(IBM-BMT)对异基因小鼠皮肤移植耐受的诱导效果。受鼠为雌性C57BL/6(H-2b,B6)小鼠,于第0天接受60Coγ射线全身照射(TBI),4 h内输注雄性BALB/c(H-2d)小鼠来源的骨髓细胞(BMC),2 d后腹腔注射环磷酰胺(CTX)。通过皮肤移植、混合淋巴细胞反应(MLR)检测耐受状态,并通过骨髓染色体分析了解BMC的植入程度。结果显示,接受IBM-BMT的B6小鼠对BALB/c小鼠的皮肤移植物平均存活时间(MST)超过300 d,显著长于其余两组(P<0.001);MLR结果证明,实验组B6小鼠获得供体特异性耐受,在耐受小鼠骨髓中可检测到一定比例的Y染色体存在。以上表明髓腔内骨髓移植可以保证异基因骨髓细胞的植入并形成混合嵌合状态,从而有效地诱导免疫耐受。     

未成熟树突状细胞诱导异基因嵌合体的形成

目的：证实供体来源的未成熟树突状细胞（imDCs）主支免疫受体小鼠后可诱导形成基因嵌合体。方法：应用供体（C57BL／6）来源的骨细胞在体外培养出imDCs，灭活后静脉输注受体小鼠（BALB／c），并于输注后不同时间输注供体来源的骨髓细胞，检测异基因嵌合体的形成。同时比较imDCs一次免疫与多次免疫对诱导嵌合体形成的影响。结果：在imDCs免疫后3d输注骨髓细胞可诱导基因嵌体合体的形成，并持续100d以上；在免疫后5d注射骨髓细胞只能形成短暂的（＜21d）、低水平（＜1％）的嵌合状态；7d后则完全不能形成嵌合。应用一次和多次imDCs免疫均能诱导形成异基因嵌合体，且维持时间均大于100d，但其嵌合程度有显著性统计学差异（P＜0．05）。结论：应用供体来源的imDCs主动脉免疫受体可诱导形成异基因嵌合体。     

同种异体大鼠嵌合体动物模型的建立及意义

目的:探讨建立同种异体大鼠嵌合体动物模型的方法,初步研究嵌合体与耐受的关系。方法:采用两种诱导方法处理受体Wistar大鼠(♀) :Ⅰ组大鼠亚致死TBI(11Gy) ;Ⅱ组大鼠TBI(7Gy) ,两组均在4小时内输入SD大鼠(♂)BMC(8×10 7) ,Ⅱ组于2天后腹腔注射CTX(5 0mg kg)。分别于BMT后2 0、4 0天通过PCR方法检测SD大鼠源性BMC在Wistar大鼠体内植活情况,并通过皮肤移植、DTH和MLR检查,判断其耐受情况。结果:经上述处理两组大鼠外周血均可测出SD大鼠源性嵌合体,皮肤移植、DTH和MLR检查显示对SD大鼠产生特异性耐受,但Ⅰ组大鼠生存情况明显不如Ⅱ组。结论:应用7GyTBI +腹腔注射CTX(5 0mg kg) +供体BMT可成功建立同种异体大鼠嵌合体模型,诱导特异性免疫耐受。     

同种MHC基因胸腺转移诱导小鼠心肌移植耐受

目的：通过胸腺内注射表达外源性主要组织相容性抗原复合物（MHC）抗原质粒PXN（N2－B19－H－2Kb），诱导异基因小鼠心肌移植耐受。方法：给BALB／C小鼠胸腺内注射质粒PXN（N2－B19－H－2Kb），将外源性的编码C57BL／6小鼠MHCI类抗原的H－2KbcDNA转移到BALBC／C小鼠胸腺，2周后行C57BL／6小鼠心肌移植。用聚合酶链反应（PCR），反转录聚合酶链反应（RT－PCR），单克隆抗体免疫萤光染色流式细胞仪检测BALB／C小鼠胸腺细胞DNA，mRNA和MHC蛋白质表达。结果：BALB／C小鼠胸腺细胞表面有外源性MHC分子表达，转染效率为5．1％，胸腺内注射质粒PXN（N2－mg－H－2Kb）能明显延长移植小鼠心肌的存活时间，平均17d，对照为8d（P＜0．01）。结论：同种MHC基因转移至受体鼠胸腺可以诱导特异性的免疫耐受。     

小鼠皮肤移植耐受诱导及微嵌合体检测

目的　探求简便易行、安全有效、有临床应用前景的移植耐受诱导方法，研究微嵌合体的形成情况及其与移植耐受的关系。方法　雄性ＢＡＬＢ／ｃ 和雌性Ｃ５７ＢＬ／６ 小鼠作为皮肤移植的供体和受体，移植前对受体小鼠单独或联合应用５Ｇｙ（５００ｒａｄ ，１Ｇｙ ＝ １００ｒａｄ） 全身照射，０ ．１ ｍｌ 抗淋巴细胞血清注射，３ ×１０７ 供体骨髓细胞静脉输注，１５０ｍｇ／ｋｇ 体重环磷酰胺腹腔注射。应用多聚酶链式反应（ＰＣＲ） 检测微嵌合体的形成。结果　单纯照射不能延长移植物的存活，也没有微嵌合体形成，而其它各实验组的皮肤移植物存活时间均较对照组明显延长，混合淋巴细胞反应和迟发型超敏反应也表现为供者特异性的降低，多种组织的微嵌合体检查均呈阳性。结论　采用比较温和的非照射的预处理方法，也可获得一定程度的免疫耐受，达到延长移植物存活的目的；移植前输注供体骨髓细胞能够促进微嵌合体的形成及移植物的存活。     

同基因造血干细胞移植免疫重建诱导小鼠皮肤移植耐受

背景：器官移植耐受的最佳效果是能够诱导对移植抗原的特异性免疫耐受。 目的：探讨小鼠异基因皮肤移植后,通过受体同基因造血干细胞移植重建免疫系统诱导移植皮肤免疫耐受的可行性。 方法：取BALB/c小鼠骨髓。以C57BL/6小鼠为供体,BALB/c小鼠为受体,进行异基因皮肤移植;32只受体鼠随机均分为4组：移植对照组、环孢素A组、照射组和骨髓移植组。 结果与结论：照射组小鼠10 d内全部死亡,外周血白细胞数呈持续性降低;而骨髓移植组小鼠长期存活,白细胞数全身照射后6 d降到最低,之后持续性增高,照射后21 d与环孢素A组比较差异无显著性意义(P > 0.05),移植皮肤存活时间显著长于其他各组(P < 0.01),其淋巴细胞浸润及组织结构破坏明显减少,小鼠脾细胞对供体小鼠脾细胞增殖反应显著降低。说明同基因骨髓细胞移植重建免疫系统可显著延长小鼠移植皮肤存活时间,可诱导供者特异性免疫耐受。     

同基因造血干细胞移植延长同种异体小鼠皮肤移植物存活时间的实验研究

为了研究同基因造血干细胞移植诱导器官移植免疫耐受的可行性。建立小鼠异基因皮肤移植模型,术后2周给予FK506腹腔注射,3周起行全身照射及同基因骨髓移植,观察记录小鼠和移植物存活情况,以流式细胞检测受体GFP嵌合表达,混合淋巴细胞反应、迟发型超敏反应检测诱导耐受的特异性和效能。实验组小鼠移植物存活时间达(29.14±4.92)d,显著长于对照组(P<0.05);GFP在BMT后4周、6周嵌合程度达到82%、91%;实验组MLR、DTH结果与对照组差异显著,提示诱导耐受具有高度特异性和高效性。同基因造血干细胞移植联合免疫抑制剂治疗可以有效诱导小鼠皮肤移植的免疫耐受。     

未成熟树突状细胞诱导建立异基因嵌合体及延长移植物存活的可能机制

目的：研究应用供体来源的未成熟树突状细胞(inDCs)注射受体小鼠后，诱导形成异基因嵌合体及延长移植物存活的机制。方法：(1)应用供体(C57BL／6)来源的骨髓细胞，在体外培养出imDCs，灭活后体内输注或体外直接刺激受体小鼠(Balb/C)的脾细胞，观察脾细胞对供体细胞的应答反应；(2)取已建立异基因嵌合体并有效延长移植物存活的受体小鼠的脾细胞，观察其对供体细胞刺激的应答反应；(3)通过半定量RT—PCR检测不同免疫状态下Th1／Th2型细胞因子的表达情况。结果：应用imDCs体外预刺激脾细胞或体内注射imDCs受鼠的脾细胞，均呈现对供鼠脾细胞刺激的特异性低应答，这种低应答主要出现在受鼠脾细胞在供鼠脾细胞刺激后的72小时内；建立异基因嵌合体并延长移植物存活的受鼠对来自供鼠脾细胞的刺激也表现为低应答，而对于无关第三者脾细胞的刺激仍保持较高水平，二者比较，统计学处理有显著性差异(P＜0．05)；在诱导形成异基因嵌合体及延长移植物存活的过程中，一定程度上显示出Th1／Th2模式的偏移。结论：应用供体来源的imDCs注射给受体，诱导形成异基因嵌合体和延长移植物存活的机制可能与imDCs诱导受体T细胞无能有关，而且此过程中在一定程度上表现为Th1向Th2方向的免疫偏移。     

雌激素处理DCs在诱导小鼠同种皮肤移植免疫耐受中的作用

目的：研究雌二醇（17β-estradiol, E₂）处理的供体骨髓来源树突细胞（dendritic cells, DCs）在诱导小鼠同种异基因皮肤移植免疫耐受中的作用。方法：体外培养小鼠骨髓来源DCs，然后用E₂处理。受体小鼠在皮肤移植前经尾静脉分别输注经E₂处理的供体小鼠DCs、供体小鼠成熟DCs以及不成熟DCs，输注PBS为对照组。1周后对受体小鼠进行同种异基因皮肤移植，手术后观察皮肤存活情况，应用流式细胞术检测手术前后受体小鼠外周血中CD4+CD25+调节性T细胞百分率的变化。结果：在同种异基因皮肤移植中，受体小鼠尾静脉输注经E2处理的DCs组与对照组和不成熟DCs组比较，移植皮肤存活时间显著延长，较不成熟DCs组存活时间平均延长10.6 d（P<0.01）；与对照组和不成熟DCs组比较，E₂处理组外周血中CD4+CD25+ 调节性T细胞百分率明显升高（P<0.01）。结论：在同种异基因小鼠皮肤移植模型中，E₂处理的供体小鼠DCs可以延长移植皮肤存活时间。     

抗TCRαβ单抗联合供体骨髓细胞输注诱导小鼠皮肤移植耐受的研究

探讨抗TCRαβ单克隆抗体联合大剂量供体骨髓细胞输注方法对同种异基因小鼠皮肤移植耐受诱导的促进作用。第 0天 ,C5 7BL/ 6 (H 2 b,B6 )小鼠尾静脉注入 2× 10 8BALB/c (H 2 d,B/c )来源的骨髓细胞 ,同时腹腔注射抗TCRαβ单克隆抗体5 0 0 μg ;第 6天进行皮肤移植 ;在不同的时间对B6小鼠进行迟发型超敏反应 (DTH )、混合淋巴细胞反应 (MLR )等耐受状态进行检测 ,并进行MLR的IL 2逆转实验、过继转移实验和嵌合状态分析以初步探讨耐受形成机制。结果显示 ,经抗TCRαβ单克隆抗体联合大剂量供体骨髓细胞输注处理的B6小鼠的供体皮肤移植物平均存活 5 0 4d ,显著长于其他各组 (P <0 0 0 1)。相对于正常对照组小鼠 ,耐受B6小鼠在DTH和MLR中均表现出显著的低反应性 (P <0 0 0 1)。IL 2逆转实验结果表明克隆无能参与了移植耐受的形成。体内、外过继转移实验均显示耐受B6小鼠脾细胞中存在抑制细胞活性。嵌合体检查结果表明在耐受B6小鼠的胸腺和脾脏中均形成了混合嵌合体 ,在皮肤移植后第 15、 30和 70天时脾脏内供体来源嵌合体水平依次为 15 86 % ,10 5 7%和 1 77% ,胸腺中依次为 8 19% ,5 72 %和 1 87% ,嵌合体水平随时间而下降。这些表明 ,抗TCRαβ单抗联合大剂量供体骨髓细胞输注可以在异基因成年小?     

免疫毒素用于自体骨髓移植治疗白血病的实验研究及初步临床

目前自体骨髓移植被越来越多地用于白血病治疗,然而在缓解期从病人抽取的骨髓细胞可能含有残留的肿瘤细胞,当大剂量放、化疗后回输给病人,将来有可能引起白血病复发。现在有很多方法可以用来去除这些瘤细胞,免疫毒素是安全有效的方法之一。本文报道了由抗CD2、CD5和CD8单抗与蓖麻毒素组成的抗T免疫毒素,抗CD9、CD10单抗与蓖麻毒素组成的抗C-ALL免疫毒素在体外对靶细胞的特异性细胞毒作用,及用于临床净化骨髓的初步结果。     

IL-3对小鼠骨髓来源树突状细胞分化发育的影响

比较 GM- CSF IL- 4与 IL- 3 IL- 4两种方法培养制备的树突状细胞 (Dendritic cell,DC)在形态、产量、免疫表型和抗原摄取能力方面的差异。用 GM- CSF IL- 4和 IL- 3 IL- 4分别诱导小鼠骨髓来源的前体细胞分化为成熟树突状细胞 ,通过相差显微镜、扫描电镜、激光共聚焦扫描显微镜进行形态观察 ,流式细胞术分析细胞免疫表型和摄取抗原能力。结果表明 ,IL- 3 IL- 4诱导的 DC产量高 ,细胞纯度好 ,形态上与 GM- CSF IL- 4诱导的DC类似 ;细胞免疫表型显示高表达 MHC 类分子 ,但低表达或不表达 CD80、CD86 ;IL- 3 IL- 4诱导的 DC具有强大的摄取抗原能力。 IL- 3替代 GM- CSF可诱导低表达共刺激分子的耐受型 DC     

供体骨髓细胞促进大鼠心脏移植耐受及机制的研究

经门静脉给予受体LEW大鼠3×10~8个DA大鼠供体脾细胞,2d后腹腔注射80mg/kg的环磷酰胺,第4天由舌静脉输注1×10~8骨髓细胞。2周后实施心脏移植手术。观察、记录移植物的存活时间,通过过继性转移实验,MLR、CTL活性测定及嵌合体分析,探讨耐受机制。结果表明,异基因心脏移植物的存活时间进一步延长;该耐受状态可被过继性转移;MLR、CTL活性表明,受体大鼠的免疫应答被特异性抑制;嵌合体水平提高。结论:异基因骨髓细胞输注可加深由脾细胞和环磷酰胺诱导的大鼠心脏移植耐受,该耐受与嵌合体水平、抑制细胞的存在有关。输注骨髓细胞对于改善、维持耐受状态,延长大鼠心脏移植物存活时间是一有效的方法。     

Patient Perspectives Regarding Allogeneic Bone Marrow Transplantation in Myelofibrosis

Hematopoietic stem cell transplantation (HCT) is a curative treatment for patients with myelofibrosis (MF); however, many HCT-eligible patients decline this potentially life-saving procedure. The reasons behind this decision are not clear. We sought to survey patients with MF to understand their perspective on HCT. A 63-question survey was posted on myeloproliferative neoplasm patient advocacy websites. A total of 129 patients with MF responded to the survey. Among these patients, 49 (41%) were referred for HCT, and 41(32%) attended the transplantation consult. Of the patients who attended the transplantation consult, 24 (59%) did not plan on going on to HCT, and 16 (41%) intended to proceed with HCT. Reasons for the decision to not undergo transplantation included the desire to not be ill, desire to not spend time in the hospital, and concerns about overall quality of life. Specifically, concerns related to financial impact and the risk of graft-versus-host disease (GVHD) were expressed. Patients who decided to proceed with HCT felt that this would extend their survival and allow them to be around family for longer. This is the first survey to investigate patient perceptions regarding HCT for MF. Less than one-half of the patients were referred for HCT, and of those, less than one-half planned on proceeding with the transplantation, suggesting that many patients do not receive this life-saving procedure. Further exploration of the basis of patients’ reluctance to proceed with HCT is warranted.     

Fatal Pulmonary Microsporidiosis Due to Encephalitozoon cuniculi Following Allogeneic Bone Marrow Transplantation for Acute Myelogenous Leukemia

Microsporidia are ubiquitous obligate eukaryotic intracellular parasites that are now felt to be more akin to degenerate fungi than to protozoa. Microsporidia can be highly pathogenic, causing a broad range of symptoms in humans, especially individuals who are immunocompromised. The vast majority of human cases of microsporidiosis have been reported during the past 20 years, in patients with HIV/AIDS, while only relatively rare cases have been described in immunocompetent individuals. However, microsporidia infections are being increasingly reported in patients following solid-organ transplanation, where the main symptom has been diarrhea. The authors report the first case of pulmonary microsporidial infection in an allogeneic bone marrow transplant recipient in the United States and only the second case in the world. The patient, with a history of Hodgkin disease followed by acute myelogenous leukemia received a T-cell-depleted graft, but succumbed to respiratory failure 63 days post transplantation. An open lung biopsy, taken just before death, was originally thought to show toxoplasmosis. The correct diagnosis of microsporidiosis was made postmortem by light and electron microscopy. DNA polymerase chain reaction analysis confirmed the diagnosis and furthermore revealed it to be the dog strain of the microsporidia species Encephalitozoon cuniculi. Although to date rarely diagnosed, microsporidial infection should also be considered in the differential diagnosis of, e.g., unexplained pulmonary infection in bone marrow transplant patients.     

Leptin Signaling Protects NK Cells from Apoptosis During Development in Mouse Bone Marrow

Increasing evidence indicates a role of leptin in immune response, but it remains largely unclear whether leptin signaling is involved in regulating NK cell development in the bone marrow （BM）. In this study, we have characterized NK cell differentiation and maturation in the BM of leptin-receptor deficient db/db mice at a prediabetic stage. Although the BM cellularity was similar to the control value, the total number of NK cells was severely reduced in mutant mice. Flow cytometric analysis of db/db BM cells revealed significantly decreased frequencies of developing NK cells at various stages of differentiation. BM db/db NK cells displayed markedly increased apoptosis but maintained normal cell cycling status and proliferative capacity. Moreover, recombinant leptin could significantly enhance the survival of NK cells from wild-type mice in cultures. Further examination on NK cell functional activity showed that db/db NK cells exhibited normal intrinsic cytotoxicity with significantly increased IL-10 production. Taken together, our findings suggest that leptin signaling regulates NK cell development via enhancing the survival of immature NK cells in mouse BM.     

Filgrastim following HLA-Identical Allogeneic Bone Marrow Transplantation: Long-Term Outcomes of a Randomized Trial

Human recombinant granulocyte colony stimulating factor reduces the duration of neutropenia following HLA-identical allogeneic bone marrow transplantation. However, its use remains controversial due to the risk of increasing the incidence of acute graft-versus-host disease (GVHD) and slower platelet recovery. To clarify these risks, we conducted a prospective randomized placebo-controlled trial of filgrastim 5 µg/kg/day i.v. from day 7 post-transplant until neutrophil recovery in 145 consecutive adults undergoing HLA-identical allogeneic bone marrow transplantation, with cyclosporine and methotrexate as GVHD prophylaxis. The primary endpoint was the incidence of acute GVHD; hematological recovery, nonrelapse mortality, and post-transplant complications were secondary endpoints. Filgrastim had no significant effect on the incidence of acute GVHD, platelet recovery, platelet transfusion requirements, chronic GVHD, or survival. Filgrastim accelerated granulocyte recovery significantly (with absolute neutrophil counts >.5?×?10⁹/L achieved after a median of 16 days versus 23 days for placebo; P < .0001), and reduced both early nonrelapse mortality (2.9% versus 10.5%; P = .042) and the duration of i.v. antibiotic therapy (18 days versus 26 days; P = .001) and hospitalization (27 versus 34 days; P = .017). In conclusion, in this setting, filgrastim reduced significantly the duration of neutropenia, i.v. antibiotic therapy, hospitalization, and early nonrelapse mortality, without increasing the risk of acute and chronic GVHD or relapse, or delaying platelet recovery.     

兔骨髓成骨细胞同种异体移植免疫反应的初步观察

以观察新生兔骨髓诱导分化为成骨细胞的能力 ,探讨同种异体成骨细胞移植的可行性 ,为进一步的研究奠定基础。取新生新西兰大白兔胫骨骨髓 ,分离后加入条件培养液体外培养。传 5代后对细胞进行形态学、碱性磷酸酶 (ALP )染色及体外矿化能力的检测。将冻存复苏的细胞以明胶海绵吸附 ,植入异体成年兔皮下、肌肉内 ,第 2、 4、 8、 12周时取材观察 ,分析其成骨能力及免疫排斥反应情况。结果显示体外诱导培养的骨髓成骨细胞是一较纯的细胞系 ,以带突起的梭形细胞为主 ,ALP染色阳性 ,连续培养 4 0d可见矿化结节形成。异体植入的成骨细胞大部分存活 ,4周后开始有类骨基质形成 ,并可见不规则的矿化骨组织 ,植入细胞周围仅见少量的淋巴细胞和嗜酸粒细胞浸润。骨髓基质细胞具有多向分化的潜力 ,异体植入的细胞仍保持基本的生物学功能 ,免疫排斥反应比较轻微 ,提示细胞异体移植是可行的     

Dynamic of Bone Marrow Fibrosis Regression Predicts Survival after Allogeneic Stem Cell Transplantation for Myelofibrosis

We correlate regression of bone marrow fibrosis (BMF) on day 30 and 100 after dose- reduced allogeneic stem cell transplantation (allo-SCT) in 57 patients with primary or post–essential thrombocythemia/polycythemia vera myelofibrosis with graft function and survival. The distribution of International Prognostic Scoring System (IPSS) risk score categories was 1 patient with low risk, 5 patients with intermediate-1 risk, 18 patients with intermediate-2 risk, and 33 patients with high risk. Before allo-SCT, 41 patients (72%) were classified as XXX [myclofibrosis (MF)]-3 and 16 (28%) were classified as MF-2 according to the World Health Organization criteria. At postengraftment day +30 (±10 days), 21% of the patients had near-complete or complete regression of BMF (MF-0/-1), and on day +100 (±20 days), 54% were MF-0/-1. The 5-year overall survival rate at day +100 was 96% in patients with MF-0/-1 and 57% for those with MF-2/-3 (P = .04). There was no difference in BMF regression at day +100 between IPSS high-risk and low/intermediate-risk patients. Complete donor cell chimerism at day +100 was seen in 81% of patients with MF-0/-1 and in 31% of those with MF-2/-3. Patients with MF-2/-3 at day +100 were more likely to be transfusion-dependent for either RBCs (P = .014) or platelets (P = .018). Rapid BMF regression after reduced-intensity conditioning allo-SCT resulted in a favorable survival independent of IPSS risk score at transplantation.