Unrelated donor leukocyte infusions to treat relapse after unrelated donor bone marrow transplantation

Allogeneic stem cell transplantation (SCT) may cure many patients with hematologic malignancies due to both the intensive conditioning therapy, and in many patients, the potent graft-vs-leukemia (GVL) effect of the donor graft. The GVL effect is mediated in large part by mature T-cells contained in the donor graft and has been defined in detail in animal models of transplantation. The GVL activity has been observed in the clinical setting after SCT from both matched siblings and unrelated donors. The best demonstration and most direct evidence of GVL activity in humans come from the use of donor leukocyte infusions (DLI). For patients who relapse with chronic myelogenous leukemia after matched sibling SCT, infusions of leukocytes collected from the original transplant donor will re-establish complete and durable remission in 60-80% of patients. DLI is less effective for more advanced phases of CML and for patients who relapse with diseases other than CML. DLI after matched sibling SCT is complicated primarily by graft-vs-host disease (GVHD), marrow aplasia, and unfortunately, relapse in some cases. There has been little information regarding the use of unrelated DLI (UDLI). Available data now shows that despite initial concerns that UDLI would result in excessive toxicity, it is an effective approach to relapse after unrelated donor marrow grafting. Response rates are similar to those seen after the use of matched sibling DLI, and many remissions remain durable. Graft-vs-host disease is a frequent complication after UDLI though the incidence and severity of GVHD is also similar to the use of matched sibling DLI. It is not clear that the GVL and GVHD effects can be separated, since the majority of responding patients also develop GVHD. The most effective cell dose for UDLI has not been established, though there does not appear to be either a dose-response or dose-toxicity relationship from UDLI. Although second unrelated donor bone marrow transplantation (BMT) may cure a small minority of patients, GVL induction with UDLI offers a safer and potentially more effective therapy for relapsed leukemia, and offers insights in methods to manipulate the human immune system for therapeutic benefit.     

Expansion of tumor-specific CD8+ T cell clones in patients with relapsed myeloma after donor lymphocyte infusion

Donor lymphocyte infusions (DLI) provide effective therapy for patients with multiple myeloma who have relapsed after allogeneic bone marrow transplantation. However, the immunological mechanisms of the graft-versus-myeloma (GVM) effect have not been defined, and the target antigens of this response have not been identified. Molecular analysis of CDR3 Vbeta repertoire after CD4+ DLI demonstrated previously that the development of GVM and graft-versus-host-disease (GVHD) were associated with the clonal expansion of distinct T-cell populations in patient peripheral blood. In the current study, we undertook a molecular and functional characterization of GVM- and GVHD-associated T-cell clones. T-cell clones associated with GVM were detectable by clone-specific PCR at a low level in peripheral blood before DLI and expanded approximately 10-fold after DLI. In contrast, T-cell clones associated with GVHD were not detectable before DLI or before the development of clinical GVHD. Two T-cell clones associated with GVM were isolated and expanded in vitro, allowing their phenotypic and functional characterization. Both GVM clones were derived from donor cells and had a CD3+CD8+CD4- phenotype. One GVM clone specifically recognized patient myeloma cells in an HLA class I-restricted manner, but was not reactive with patient normal bone marrow cells or patient EBV transformed B cells. Taken together, these findings suggest that the GVM response is mediated by donor-derived CD8+ T-cell clones with antimyeloma specificity that may be present before DLI. In contrast, T-cell clones associated with GVHD are expanded de novo after DLI.     

Salvage therapy for relapsed mediastinal B-cell lymphoma with allogeneic HLA-identical related donor bone marrow transplantation, donor lymphocyte infusion and IDEC-C2B8.

Primary B-cell lymphoma of the mediastinum is an aggressive non-Hodgkin's lymphoma with distinct clinicopathologic features. Response rates are between 60-80% following intensive chemotherapy regimens. Poor responders or patients with an early relapse usually do not achieve a prolonged second remission with conventional salvage therapy protocols and therefore qualify for intensive or experimental approaches. Here we describe two patients of same age, gender and stage with primary mediastinal B-cell lymphoma and an early relapse after the first courses of combination chemotherapy and irradiation of the mediastinum. One patient relapsed after a salvage therapy with allogeneic donor-related bone marrow transplantation and donor lymphocyte infusion but responded again with a continuing good partial remission after infusion of the chimeric anti-CD20 antibody IDEC-C2B8. For the other patient an allogeneic bone marrow transplantation was not possible. He finally failed to respond to salvage therapy with IDEC-C2B8 and died of progressive disease. The anti-CD20 antibody IDEC-C2B8 induced a partial remission in a patient with primary mediastinal B-cell lymphoma refractory to other therapeutic approaches, including allogeneic bone marrow transplanatation (alloBMT), donor lymphocyte infusion (DLI) and irradiation. The role of IDEC-C2B8 as a component of salvage regimens appears to be worthy for further evaluation in high-risk patients with primary mediastinal B-cell lymphoma     

Combination chemotherapy of intermediate-dose cytarabine, idarubicin, plus etoposide and subsequent mobilized donor leukocyte infusion for relapsed acute leukemia after allogeneic bone marrow transplantation

The efficacy and side effects of intermediate-dose cytarabine, idarubicin plus etoposide and subsequent donor leukocyte infusion (DLI) were investigated in patients with acute leukemia who relapsed after allogeneic bone marrow transplantation (BMT). Patients were given cytarabine continuous i.v. (1 g/m2 per day x 5), idarubicin i.v. (12 mg/m2 per day x 3), and etoposide i.v. infusion (150 mg/m2 per day x 3). Two days later, G-CSF mobilized donor leukocytes were infused for 2 days. No graft-versus-host disease (GVHD) prophylaxis was given. Between August 1997 and February 2000, 13 patients enrolled (eight acute myeloid leukemia (AML) and five acute lymphoblastic leukemia (ALL)). All patients finished chemotherapy and DLI. Eleven patients (85%) achieved complete remission (CR) at median 27 days after DLI. After median follow up of 10.9 months (2.5-33.3), five of 11 patients who achieved CR relapsed. Overall, six of 13 patients were surviving (6/8 AML and 0/5 ALL, P=0.059). Marrow recovery after chemotherapy and DLI was rapid (12 days for absolute neutrophil count (ANC) >500/microl). Side effects included fever with neutropenia (100%), pneumonia (46%), grade II-IV mucositis (69%), grade III-IV acute GVHD (45%), and extensive chronic GVHD (64%). One patient died from chronic GVHD. Chemotherapy containing intermediate-dose cytarabine and DLI produced a high CR rate in acute leukemia in relapse after allogeneic BMT. A fraction of patients are surviving long term. Side effects were substantial but manageable.     

Treatment of relapsed acute myeloid leukemia after allogeneic bone marrow transplantation with chemotherapy followed by G-CSF-primed donor leukocyte infusion: a high incidence of isolated extramedullary relapse.

For patients with acute myeloid leukemia (AML) relapsed after allogeneic bone marrow transplantation (BMT), donor leukocyte infusion (DLI) as sole therapy has very limited efficacy. We tested the effects of cytoreductive chemotherapy, followed immediately by G-CSF-primed DLI (chemotherapy followed by DLI, Chemo-DLI), in 16 AML patients who relapsed after allogeneic BMT. In all, 10 of these patients achieved complete remission (CR), four of whom remain alive in CR at a median follow-up of 1488 days after DLI. The 2-year overall survival (OS) for the entire cohort was 31%. The 1-year OS for patients with post-BMT remission of 6 months or longer was 55%, compared with 0% for patients with post-BMT remission of less than 6 months, making post-BMT remission duration the only significant prognostic factor for OS (P=0.015). These findings suggest that Chemo-DLI could induce durable remissions in a proportion of relapsed AML patients with relatively long post-BMT remission duration. All five patients who relapsed after achieving CR with Chemo-DLI relapsed at extramedullary sites in the presence of continuous bone marrow remission, suggesting uneven graft-versus-leukemia effects in different parts of the body. Although our data should be interpreted cautiously considering the limited number of patients, isolated extramedullary relapse seems to be common after Chemo-DLI.     

Immunomodulation with dendritic cells and donor lymphocyte infusion converge to induce graft vs neuroblastoma reactions without GVHD after allogeneic bone marrow transplantation

Background:

Mounting evidence points to the efficacy of donor lymphocyte infusion (DLI) and immunisation with tumour-pulsed dendritic cells (DC) in generating graft vs leukaemia reactions after allogeneic bone marrow transplantation (BMT). We assessed the efficacy of DLI and DC in generating potent graft vs neuroblastoma tumour (GVT) reactions following allogeneic BMT.

Methods:

Mice bearing congenic (H2K^a) Neuro-2a tumours were grafted with allogeneic (H2K^b) T-cell-depleted bone marrow cells. Tumour-pulsed donor DC (DC^Neuro2a) were inoculated (on day +7) in conjunction with donor (H2K^b) and haploidentical (H2K^a/b) lymphocytes.

Results:

Murine Neuro-2a cells elicit immune reactions as efficient as B lymphoma in major histocompatibility complex antigen-disparate mice. Lymphopenia induced by conditioning facilitates GVT, and transition to adaptive immunity is enhanced by simultaneous infusion of and DC^Neuro2a and lymphocytes devoid of graft vs host (GVH) activity (H2K^a/b). In variance, the efficacy of DC-mediated immunomodulation was diminished by severe graft vs host disease (GVHD), showing mechanistic dissociation and antagonising potential to GVT.

Conclsions:

The GVHD is not a prerequisite to induce GVT reactivity after allogeneic BMT, but is rather detrimental to induction of anti-tumour immunity by DC-mediated immunomodulation. Simultaneous inoculation of tumour-pulsed donor DC and DLI synergise in stimulation of potent GVT reactions to the extent of eradication of established NB tumours.     

Salvage chemotherapy with donor lymphocyte infusion and STI 571 in a patient relapsing with B-lymphoblastic phase chronic myeloid leukemia after allogeneic bone marrow transplantation

Relapse is the main cause of treatment failure following hematopoietic stem cell transplantation for blastic phase chronic myeloid leukemia. Treatment options including donor lymphocyte infusion, second transplantation, interferon- and re-induction chemotherapy are often unsuccessful. We report a patient with blastic phase chronic myeloid leukemia relapsing after allogeneic stem cell transplantation. The post-transplant leukemia was characterized with B-lymphoid markers and multiple genetic abnormalities including double Ph-chromosomes. The disease was treated with three courses of salvage chemotherapy combined with donor lymphocyte infusion and bcr-abl tyrosine kinase inhibitor. The leukemia proved to be non-responsive both to immune therapy and STI 571. The presented case demonstrates the need for combination approaches in post-transplant relapsed leukemia and discusses the possible contributing mechanisms of STI-571 resistance.     

Donor leukocyte infusion from immunized donors increases tumor vaccine efficacy after allogeneic bone marrow transplantation

Donor T cells play a critical role in mediating both harmful graft-versus-host disease (GVHD) and beneficial graft-versus-tumor effect after allogeneic bone marrow transplantation (BMT). We have recently demonstrated a novel treatment strategy to stimulate specific antitumor activity with preservation of tolerance to host antigens after T cell-depleted allogeneic BMT by vaccination of recipients with irradiated B16 melanoma cells engineered to secrete granulocyte-macrophage colony-stimulating factor. In this murine system, donor leukocyte infusion from a donor immunized with the recipient-derived B16 vaccines enhanced clinical activity of tumor vaccines without exacerbating GVHD. CD4(+) T cells are essential for this enhancement. In vitro analysis of splenocytes from donor leukocyte infusion donor mice demonstrated that immunization of donors with the recipient-derived B16 vaccines elicited potent T-cell proliferation and cytokine responses specific to B16 antigens. These results demonstrate that immunization of donors with recipient-derived tumor vaccines preferentially induces tumor-specific T-cell responses and that vaccination of both donors and recipients can generate potent antitumor immunity without exacerbating GVHD. This strategy has important implications to prevent recurrence of malignancies after BMT.     

Changes in T lymphocyte subsets in mice with CT26 colon tumors after treatment with donor lymphocyte infusion

The objective of this study was to detect changes in T lymphocyte subpopulations in mice with CT26 subcutaneous colon cancer after treatment with donor lymphocyte infusion (DLI) and cyclophosphamide (CP) chemotherapy. A colon cancer model was established by subcutaneous injection of CT26 carcinoma cells into BALB/C mice. The mice were randomized into different treatment groups. We recorded survival times, tumor growth inhibition rates, histopathological changes, and T lymphocyte subsets in peripheral blood of the mice. Mice treated with DLI and CP survived 33.5?±?5.02 days, which was significantly longer than the survival time of untreated control mice (16.7?±?2.98 days, P?<?0.01). In addition, the tumor inhibitory rate was higher in mice treated with DLI and CP (89.3 %) than that in mice treated with CP or DLI alone (67.1 and 34.5 %, respectively). There were higher levels of T lymphocytes that were CD3⁺ and CD4⁺ in mice treated with DLI alone or the combination of CP and DLI (P?<?0.05), and the ratio of CD4⁺/CD8⁺ cells was significantly improved in these mice (P?<?0.05). DLI combined with chemotherapy significantly prolonged survival and inhibited tumor growth in mice with CT26 colon cancer. This treatment might also improve immune function in these mice. Donor spleen cells that include high numbers of allogeneic lymphocytes and a few stem cells could induce a graft-versus-tumor effect, leading to elimination of residual cancer cells. This indicates that it is potentially a feasible adoptive cellular immunotherapy strategy for the management of solid tumors.     

白血病单倍型骨髓移植后T细胞克隆的T细胞受体分子特征

背景与目的:临床及实验研究结果表明,异基因造血干细胞移植后T细胞免疫恢复延迟,单倍型造血干细胞移植免疫重建与临床经过密切相关.本课题通过T细胞受体谱型分析,研究白血病单倍型骨髓移植后细胞免疫重建特点及与移植物抗宿主病(GVHD)相关的T细胞克隆的T细胞受体β链可变区互补决定3区(TCRBV CDR3)分子特征.方法:应用RT-PCR扩增9例不同类型白血病单倍型骨髓移植后患者及5名正常供者的外周血的TCRBV 24个家族的基因序列,并通过基因扫描的方法判断TCRBV家族的克隆表达情况、CDR3克隆性质及测定BV家族的利用率.对于单克隆表达的与GVHD相关T细胞克隆进行序列测定.结果:在移植后10～19个月,TCRBV家族的利用仍处于不均一状态,检测到部分BV家族缺失,部分家族出现寡克隆、单克隆T细胞增殖.在疾病相对稳定的4例患者中,在9～14个BV家族中有表达,且多克隆家族的表达率在50%以上.另5例为疾病处于活动状态,发生Ⅱ～Ⅲ度GVHD或巨细胞病毒(CMV)感染,对BV家族的利用明显减少,多为单克隆或寡克隆表达,多克隆表达率仅30%,未发现共用的单克隆BV家族.其中2例患者在治疗前后不同时间,随着疾病趋于稳定,BV家族的利用增加,CDR3的多克隆群体增加.得到的一组与GVHD直接相关的TCRBV CDR3分子,通过比较未发现共同使用的氨基酸基序.结论:单倍型骨髓移植后10～19个月,在疾病相对稳定期,9～12个BV家族有表达,以多克隆家族表达为主.在疾病活动状态,BV家族表达减少,以单克隆或寡克隆表达为主.与GVHD相关的克隆性T细胞,未发现共同使用的CDR3氨基酸基序.     

Comparative outcomes of T-cell-depleted and non-T-cell-depleted allogeneic bone marrow transplantation for chronic myelogenous leukemia: impact of donor lymphocyte infusion.

PURPOSE: Donor lymphocyte infusion (DLI) can restore complete remission in patients with chronic myelogenous leukemia (CML) who have relapsed after T-cell-depleted (TCD) allogeneic bone marrow transplantation (BMT). The existence of salvage treatment for patients with DLI after TCD allogeneic BMT prompted an evaluation of overall outcome after CD6+ -TCD allogeneic BMT for patients treated during the time when DLI has been available. PATIENTS AND METHODS: We performed a retrospective analysis of outcomes of 46 patients who underwent TCD allogeneic BMT for stable-phase CML and compared these outcomes with those of 40 patients who underwent non-TCD allogeneic BMT. All subjects were patients at one of two neighboring institutions during a period when DLI was available. All patients received marrow from HLA-identical sibling donors, underwent similar myeloablative regimens, and had similar pretreatment characteristics. RESULTS: After BMT, the TCD group had a lower incidence of grade 2 to 4 acute (15% v 37%, P = .026) and chronic graft-versus-host disease (GVHD) (18% v 42%, P = .024) than did the non-TCD group. The 1-year treatment-related mortality rates for the TCD group and the non-TCD group were 13% and 29%, respectively (P = .07). The estimated 3-year probability of relapse (cytogenetic or hematologic) was higher for patients in the TCD group than for patients in the non-TCD group (62% v 24%, P = .0003). Twenty-three patients (20 in the TCD group and three in the non-TCD group) received and were assessable for response to DLI. After DLI, 17 of 20 patients in the TCD group and two of three patients in the non-TCD group achieved complete remission. Donor lymphocyte infusion induced GVHD in nine of 23 patients. Thirty (65%) of 46 patients in the TCD group and 27 (69%) of 39 assessable patients in the non-TCD group remained alive without evidence of disease. The estimated 3-year overall survival rates were similar for the TCD group and the non-TCD group (72% v 68%, respectively; P = .38). At last follow-up, there was no difference in the overall prevalence of GVHD or the proportion of patients requiring immunosuppressive agents between groups. CONCLUSION: These results suggest that the combination of T-cell depletion and post-BMT DLI is a viable treatment option for patients undergoing allogeneic BMT for CML and should be prospectively compared with traditional forms of GVHD prophylaxis.     

Induction of graft-versus-leukemia to prevent relapse after partially lymphocyte-depleted allogeneic bone marrow transplantation by pre-emptive donor leukocyte infusions.

In this prospective study we analyzed pre-emptive donor leukocyte infusions (DLI) in 82 consecutive patients transplanted with partially T cell-depleted grafts for acute myeloid leukemia, acute lymphoid leukemia, chronic myeloid leukemia, refractory anemia with excess of blasts, refractory anemia with excess of blasts in transformation and multiple myeloma. Donors were HLA-identical siblings. Patients without significant acute (>grade 1) and/or chronic GVHD were scheduled to be treated with DLI (35 patients) and 31 actually received DLI. Patients who developed acute GVHD >grade 1 and/or chronic GVHD were not scheduled to receive DLI and served as a comparison group (47 patients). The median interval between BMT and DLI was 22 weeks. The first six patients received 0.7 x 10(8) CD3+ cells/kg body weight (b.w.). Five out of these six patients developed acute GVHD (grade 1: n = 2, grade 3: n = 2 and grade 4: n= 1) which was more frequent and more severe than we had anticipated. In the next 25 patients the number of T lymphocytes was diminished to 0.1 x 10(8) CD3+ cells/kg b.w. which resulted in less frequent and less severe GVHD. Eight patients in this group developed acute GVHD (grade 1: n = 4, grade 2: n = 4) and three patients had limited chronic GVHD. Patients in the DLI group needed more time to establish complete donor chimerism confirmed by a higher number of mixed chimeras at 6 months after BMT. The projected 3-year probability of disease-free survival was 77% for the 35 patients intended to treat with DLI and 45% for the patients of the comparison group (P = 0.024). Relapse rate at 36 months after transplantation was 18% in the patients who were intended to treat with DLI and 44% in the comparison group (P = 0.026). We conclude that pre-emptive DLI is feasible and generates favorable relapse rates in patients who are at high risk for relapse. Furthermore, the incidence and severity of GVHD disease after DLI is dependent on the number of CD3+ cells infused.     

Regulation of alloresponses after bone marrow transplantation using donor T cells expressing a thymidine kinase suicide gene

Donor T cells have a critical role in promoting engraftment after allogeneic bone marrow transplantation (BMT), but also cause graft versus host disease (GVHD). Ex vivo T cell depletion has been an effective strategy to reduce GVHD but has been associated with impaired alloengraftment and host immunity. Using an MHC-mismatched murine model, we have examined an alternative approach to GVHD prevention whereby donor T cells are selectively eliminated in vivo after BMT using transgenic T cells in which a thymidine kinase (TK) suicide gene is targeted to the T cell. Lethally irradiated AKR/J (H-2k) mice transplanted with TCD C57BL/6 (B6)(H-2b) bone marrow (BM) plus B6 TK+ T cells and then treated with GCV post-BMT had significantly less GVHD severity and improved immune reconstitution compared to untreated mice, providing proof of principle that this strategy could mitigate GVHD. To assess the impact of GCV administration on alloengraftment, sublethally irradiated AKR mice were transplanted with TCD B6 BM alone or admixed with limiting numbers (5 x 10(5)) of B6 TK+ T cells. When tested 3-4 weeks post-transplant, control TCD BM mice all rejected their grafts. Conversely, > 80% of GCV-treated mice had sustained donor T cell engraftment comparable to what was observed in untreated animals. Notably, GCV-treated mice were more likely to have mixed T cell chimerism early post-BMT than untreated animals, however, nearly all GCV-treated mice progressed to complete donor T cell engraftment by 2-3 months post-transplant. Preservation of engraftment was critically dependent upon the GCV administration schedule and required that GCV be delayed for at least one week post-transplant. These studies demonstrate that specific incorporation of a suicide gene into donor T cells is a viable strategy that can be employed to reduce GVHD without compromising alloengraftment.     

Minor histocompatibility antigen-specific T cells with multiple distinct specificities can be isolated by direct cloning of IFNgamma-secreting T cells from patients with relapsed leukemia responding to donor lymphocyte infusion.

Graft-vs-leukemia reactivity after donor lymphocyte infusion (DLI) can be mediated by donor T cells recognizing minor histocompatibility antigens (mHags) on recipient hematopoietic cells. To study the diversity of cells involved in this immune response, hematopoietic cell reactive T cells were directly clonally isolated from peripheral blood of patients entering complete remission after DLI. T cells were briefly stimulated with bone marrow cells from patients pretransplant, and IFNgamma-secreting T cells were directly clonally isolated, and expanded. Cytotoxic T-lymphocyte (CTL) clones from individual patients used multiple distinct HLA-restricting molecules and varied in reactivity against patient-derived normal and/or malignant hematopoietic cells. For each patient, CTL clones specific for known immunodominant mHags as well as distinct unknown mHags were found. Within individual patients, CTL clones using the same HLA-restricting element could show differential recognition patterns, indicating further diversity in mHag reactivity. CTL clones from individual patients exhibiting identical specificities could show oligoclonal origin. In conclusion, the direct cloning technique shows that the response to hematopoietic cells after DLI is directed against multiple distinct mHags, including but not limited to known immunodominant mHags, implying that immunotherapy with T cells against multiple mHag specificities may be more effective in eradicating malignant cells.     

The outcome and characteristics of patients with relapsed adult T cell leukemia/lymphoma after allogeneic hematopoietic stem cell transplantation

Treatment options for patients with adult T cell leukemia/lymphoma (ATLL) who have relapsed disease after allogeneic hematopoietic stem cell transplantation (allo‐HSCT) are limited. To clarify which patients with ATLL are likely to benefit from these treatment options and to define patient populations for novel treatments, we performed a nationwide retrospective analysis of 252 Japanese patients who had relapsed ATLL after allo‐HSCT. Some long‐term survivors remained after tapering and withdrawal of immunosuppressive agents. Thirty‐six patients who received donor lymphocyte infusion had a better overall survival (OS) in comparison to those who did not [hazard ratio (HR), 0.63; 95% confidence interval (CI), 0.43‐0.93; P = .02], suggesting the efficacy of a graft‐versus‐ATLL (GvATLL) effect even after relapse. Multivariate analysis demonstrated that skin lesions at initial relapse of ATLL were independently associated with higher OS (HR, 0.41; 95% CI, 0.22‐0.74; P = .003), indicating that the skin is a susceptible target organ of GvATLL. This study suggested that enhancement of a GvATLL effect is a potential therapeutic option for relapsed disease after allo‐HSCT. Further investigations of incorporation of immune‐based approaches with new molecular target drugs into the therapeutic options of patients with ATLL before and after transplantation are warranted.     

髓腔内造血干细胞移植联合供者淋巴细胞输注对GVHD和GVL的影响

 目的　观察髓腔内供者淋巴细胞输注（IBM-DLI）对急性淋巴细胞白血病小鼠异基因外周造血干细胞移植（allo-PBSCT）后移植物抗宿主病（GVHD）和移植物抗白血病效应（GVL）的影响。方法　雌性C57BL／6小鼠为受鼠建立白血病模型,接受全身照射(TBI)预处理后,输注雄性BABL/C小鼠来源的经rhG-CSF动员后的外周造血干细胞,分别经尾静脉（IV）和髓腔内进行DLI,2天后腹腔注射环磷酰胺（CTX）,观察移植后小鼠的生存状态和GVHD发生情况,应用流式细胞仪检测受鼠体内嵌合体形成和CD+4 CD+25调节性T细胞（Treg）比例。结果　IBM-DLI组的受鼠GVHD发生比例和死于白血病的小鼠比例均较IV-DLI组明显减低（P＜0.01）;移植后第7天各组受鼠骨髓中供鼠来源的细胞比例均在95 ％以上;与IV-DLI组比较,脾细胞中Tregs比例在IBM-DLI组明显升高（P＜0.01）。结论　与IV-DLI相比,IBM-DLI有利于减轻GVHD的发生,并保留GVL效应,其机制可能与受鼠体内Tregs细胞比例增高有关。