scholarly journals Myeloablative intensified conditioning regimen with in vivo T-cell depletion (ATG) followed by allografting in patients with advanced multiple myeloma. A phase I/II study of the German Study-group Multiple Myeloma (DSMM)

2003 ◽  
Vol 31 (11) ◽  
pp. 973-979 ◽  
Author(s):  
Nicolaus Kröger ◽  
Hermann Einsele ◽  
Daniel Wolff ◽  
Jochen Casper ◽  
Mathias Freund ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cell ◽  
Phase I ◽  
Conditioning Regimen ◽  
Cell Depletion ◽  
Study Group ◽  
T Cell Depletion ◽  
German Study

Fludarabine-Busulfan Conditioning and In Vivo T-Cell Depletion with Reduced Dose of ATG Followed by Allografting Induces Durable Responses in Patients with Advanced Multiple Myeloma with No Grade III-IV aGvHD.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3029-3029
Author(s):  
Nizar J. Bahlis ◽  
Douglas A. Stewart ◽  
Mary Lynn Savoie ◽  
Christopher Brown ◽  
Andrew Daly ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cell ◽  
Acute Gvhd ◽  
Chronic Gvhd ◽  
Conditioning Regimen ◽  
Cell Depletion ◽  
Cell Transplant ◽  
T Cell Depletion ◽  
Grade Iii

Abstract Background: We have investigated a conditioning regimen with Fludarabine and intravenous Busulfan with reduced ATG dose in patients with advanced and poor prognosis myeloma exploring the possibility that a low dose ATG may be sufficient enough to prevent severe GvHD without completely suppressing the graft vs myeloma effect. Methods: 15 patients received a conditioning regimen consisting of fludarabine 50mg/m2 on days -6 to -2 and IV BU (Busulfex, ESP Pharma) at a “myeloablative” dose of 3.2 mg/kg daily days -5 to -2 inclusive. All pts received Thymoglobulin (Genzyme) 4.5 mg/kg in divided doses over 3 consecutive days pre-transplant finishing D0, cyclosporine A and methotrexate with folinic acid. Results: The median age was 49 years (range 40–61). 14 (93.3%) patients had stage III (DS) disease with a median β2-microglobulin 3.12 mg/dl (1.82–5.75) and 7/11 (63.6%) in whom FISH studies were available had deletion 13, 5/15 (33.3%) patients had relapsed or progressed within 2 years of prior autologous stem cell transplant and 4 (26.6%) had progressed while on thalidomide /Dex salvage treatment. The disease status prior to allogeneic transplant was partial response (PR) in 6/15 (40%) and progressive disease (PD) in 9/15 (60%). 2/15 had plasma cell leukemia. The median number of bone marrow plasma cells prior to allo-transplant was 16% (range 3%-85%). Donors were matched siblings (MRD) for 13 (86.7%) and alternate donors in 2 (13.3%, unrelated with 2 C antigen mismatch). Cell source was blood in 14/15 (93.3%). Acute GVHD grade II-IV occurred in only 1 patient (6.6%) with no grade III-IV acute GVHD. Chronic GVHD occurred in 9/15 (60%). The TRM was 6.6%. Among 14/15 patients evaluable for response, the overall response rate (CR+PR) was 53.3% (2 CR, 6 PR, 1 MR and 5 PD); 37.5% (1CR, 2PR, 1MR and 4PD) for pts with PD at the time of the transplant and 71.4% (4PR, 1MR and 1PD) for pts with del13. After a median follow-up of 40.9 months (range 36–65.2), the estimated OS and PFS at 4 years for all patients is 38.9% (CI 95%: 13.1–64.7%) and 20.0% (CI 95%: 0–40.3%) respectively. For patients with del13 the estimated OS and PFS at 4 years is 38.1% (CI 95%: 0–77.9%) and 0% respectively. Conclusion: In vivo T-cell depletion with ATG results in a low rate of severe aGvHD with low treatment-related mortality and a substantial number of long-term survivors among patients with advanced multiple myeloma. The detection of deletion 13 by FISH however remains a predictor of short progression free survival. Figure Figure

Modulated Cyclophosphamide-Based In Vivo T-Cell Depletion Promotes Engraftment With Minimal Gvhd and Low Toxicity In Fanconi Anemia Patients

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4561-4561
Author(s):  
Monica S Thakar ◽  
Mark C. Walters ◽  
Brenda M. Sandmaier ◽  
Rainer Storb ◽  
Mary E. D. Flowers ◽  
...  
Keyword(s):  
T Cell ◽  
Fanconi Anemia ◽  
Hematopoietic Cell Transplantation ◽  
Conditioning Regimen ◽  
Cell Depletion ◽  
T Cell Depletion ◽  
Old Patients ◽  
Post Transplant ◽  
Small Series

Building on a successful non-myeloablative conditioning regimen developed in Seattle (Blood 2003), Luznik and O´Donnell et al created a protocol that incorporates post-transplant cyclophosphamide (CY) after human leukocyte antigen (HLA)-haploidentical hematopoietic cell transplantation (HCT) (BBMT 2008). This method both promotes engraftment while selectively-depleting alloreactive donor T cells to prevent graft-versus-host disease (GVHD). We have previously shown that Fanconi Anemia (FA) patients can be treated with CY 60 mg/kg in a conditioning regimen with minimal toxicity (BBMT 2007), thus we adapted this post-HCT CY strategy for in vivo T-cell depletion in patients with FA. Between 2008 and 2012, four patients from three North American centers with FA and severe marrow failure in the absence of HLA-matched donors underwent HLA-haploidentical HCT. All four patients were referred for transplantation with minimal to no transfusion burden and all were in excellent clinical condition with HCT-CI scores of 0-2 and Lansky scores of 90-100%. Median age at transplant was 9.7 (6.9-11.9) years old. Patients were transplanted at a median of 1.6 (range, 0.6 -7.1) years after FA diagnosis. Conditioning consisted of fludarabine (150 mg/m2) and 2 Gy total body irradiation; one patient also received CY (10 mg/kg), which was deleted in subsequent patients to decrease the risk of mucositis. Marrow was infused on day 0, followed by post-grafting immunosuppression with CY (25 mg/kg/day, days +3, +4), mycophenolate mofetil, and cyclosporine, the latter two beginning at day +5 with plans to continue until days +35 and +180, respectively. Full donor engraftment was seen in all patients. Two patients developed acute grade I GVHD and none of the four patients has developed chronic extensive GVHD to date. With a follow-up of 5 years, 1 year, 11 months, and 9 months, all four patients are alive with stable, full donor chimerism, and are transfusion independent. While two patients required cyclosporine beyond day +180, only one patient currently remains on low-dose immunosuppression for treatment of limited chronic skin GVHD, which has now resolved. Our results confirm that modulated post-HCT CY can be used in patients with FA to promote engraftment across histocompatibility barriers. Despite concerns for both excessive toxicity related to CY and severe GVHD related to minimizing the dose of post-transplant CY, none of the FA patients in our small series experienced these problems. Our findings also suggest that transplant should not be delayed when there is lack of an HLA-matched donor. FA patients with few comorbidities and minimal transfusion burden can successfully undergo this HLA-haploidentical HCT approach. Disclosures: Off Label Use: MMF.

scholarly journals Impact of Donor-Derived CD34+ Infused Cell Dose on Outcomes of Patients Undergoing Allo-HCT Following Reduced Intensity Regimen for Myelofibrosis:a Study from the Chronic Malignancies Working Party of the EBMT

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3338-3338
Author(s):  
Tomasz Czerw ◽  
Vittoria Malpassuti ◽  
Simona Iacobelli ◽  
Linda Koster ◽  
Nicolaus Kröger ◽  
...  
Keyword(s):  
T Cell ◽  
Research Funding ◽  
Independent Predictor ◽  
Cell Depletion ◽  
Study Group ◽  
T Cell Depletion ◽  
Cd34 Cells ◽  
Donor Type ◽  
Higher Doses

Introduction: Cellular composition of grafts is believed to be one of the significant determinants of outcomes of reduced-intensity conditioning (RIC) allogenic hematopoietic cell transplantation (allo-HCT). However, inconsistent results of the influence of CD34+ cells dose on the incidence of graft-versus-host disease (GVHD), disease control and survival have been reported in studies published thus far. Allo-HCT remains the only potentially curative treatment modality for eligible patients with myelofibrosis (MF). As patients with this diagnosis were underrepresented or not included in the above mentioned analyses, this EBMT registry study aimed to determine impact of CD34+ cell counts on allo-HCT results in this population. Methods: Six hundred and fifty seven patients with primary or secondary MF transplanted with use of peripheral blood (PB) as a source of stem cells after RIC regimen (Fludarabine/Melphalan, N=536 (82%); Fludarabine/Busulphan, N=121 (18%)) between 2000 and 2016 were included. Stem cell donor type was HLA-identical sibling (MSD; N=249, 38%) or unrelated (UD; N=408, 62%). Use of ex vivo T-cell depletion and post-transplant cyclophosphamide to prevent GVHD were the exclusion criteria. Median patient age was 58 (range, 22-76) years. In-vivo T-cell depletion was used in 526 (80%) of cases. Median transplanted CD34+ dose was 6.6 (2-29) x 10^6 per kg of recipient body weight. Median follow-up was 46 (2-194) months. Patient and transplant characteristics are summarized in Table 1. Results: We did not observe any impact of CD34+ cells dose on outcome variables in the whole study group. However, in an analysis adjusted for donor type, among patients transplanted from a MSD, the 2yr overall survival (OS) probability was 77% for those transplanted with higher doses of CD34+ cells (defined as >7.0 x 10^6/kg) compared to 60% for lower CD34+ counts (below 7.0 x 10^6/kg), P=0.007 (Figure 1). The corresponding probabilities of 2yr non-relapse mortality (NRM) were 16% and 29% (P=0.04), respectively (Figure 2). In multivariate analysis, for patients transplanted from a MSD, higher CD34+ dose was an independent predictor for better survival (HR 0.56; P=0.01) and lower risk of NRM (HR 0.54; P=0.02). We did not find any association between CD34+ counts with probability of engraftment, the incidence of acute (aGVHD) and chronic (cGVHD) nor disease relapse. The effect of cell dose was not seen in the UD cohort. Factors associated independently with an unfavorable outcome in the whole study group were: older patient age and transplantation from CMV seronegative donors to seropositive recipients for OS and NRM and use of an UD and female donor for NRM. Allo-HCT from UD was also an independent predictor for higher incidence of aGVHD and lower probability of engraftment. Use of in vivo T-cell depletion was a protective factor for aGVHD. It was in turn associated with higher risk of relapse. Conclusions: Our analysis suggests a potential survival benefit for MF patients treated with RIC PB-allo-HCT from MSD with higher doses of CD34+ cells (threshold > 7.0 x 10^6/kg). We suggest that this factor should be taken into consideration when planning and performing hematopoietic cell apheresis. Disclosures Kröger: Celgene: Honoraria, Research Funding; DKMS: Research Funding; JAZZ: Honoraria; Medac: Honoraria; Neovii: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Riemser: Research Funding; Sanofi-Aventis: Research Funding. Robin:Novartis Neovii: Research Funding. Chevallier:Daiichi Sankyo: Honoraria; Jazz Pharmaceuticals: Honoraria; Incyte: Consultancy, Honoraria. Mielke:Bellicum: Consultancy, Honoraria, Other: Travel (via institution); EBMT/EHA: Other: Travel support; Miltenyi: Consultancy, Honoraria, Other: Travel and speakers fee (via institution), Speakers Bureau; IACH: Other: Travel support; Jazz Pharma: Honoraria, Other: Travel support, Speakers Bureau; ISCT: Other: Travel support; GILEAD: Consultancy, Honoraria, Other: travel (via institution), Speakers Bureau; Celgene: Honoraria, Other: Travel support (via institution), Speakers Bureau; DGHO: Other: Travel support; Kiadis Pharma: Consultancy, Honoraria, Other: Travel support (via institution), Speakers Bureau. Snowden:Janssen: Honoraria; Mallinckrodt: Honoraria; Kiadis: Membership on an entity's Board of Directors or advisory committees; IDMC: Honoraria; Jazz: Honoraria; Gilead: Honoraria. Blaise:Sanofi: Honoraria; Pierre Fabre medicaments: Honoraria; Molmed: Consultancy, Honoraria; Jazz Pharmaceuticals: Honoraria. Hernandez Boluda:Incyte: Other: Travel expenses paid. McLornan:Jazz Pharmaceuticals: Honoraria, Speakers Bureau; Novartis: Honoraria.

scholarly journals Overall Survival Improvement Following ALLO-SCT in Patients Older THAN 60 YEARS: A Gruppo Italiano Trapianto DI Midollo Osseo (GITMO) Registry Study

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1786-1786
Author(s):  
Michele Malagola ◽  
Nicola Polverelli ◽  
Massimo Martino ◽  
Vicky Rubini ◽  
Maria Teresa Lupo Stanghellini ◽  
...  
Keyword(s):  
T Cell ◽  
Elderly Patients ◽  
Conditioning Regimen ◽  
Disease Status ◽  
Cell Depletion ◽  
Acute Leukemias ◽  
T Cell Depletion ◽  
Over Time ◽  
Selection Of

Abstract The upper age-limit for patients with hematological malignancies eligible for allo-SCT progressed to 70-75 years. As a consequence, an increase of older patients submitted to allo-SCT has been observed worldwide and in Italy as well. This registry-based retrospective study on behalf of GITMO (GITMO AlloEld) describes the transplant activity among elderly patients in Italy, between 2000 and 2017. Thiry GITMO Centers participated to the Study. 2061 allo-SCTS in patients older than 60 years were exported from PROMISE database and 1996 first transplants were analysed. The median age of the patients at transplant was 63,5 years (59,5-77,8). The most commonly transplanted diseases were acute leukemias and myelodisplastic syndromes (67,5%). 28% and 27% of the patients showed a HCT-CI of 1-2 or grater than 3, respectively. The KPS was 100% in 27,2% and 90% in 42,9% of the cases. 32% of the patients received a myeloablative conditioning regimen and 55% of the patients received an in vivo T-cell depletion (either post transplant cyclophosphamide or ATG). With a median follow up of 10,4 years, the OS at 5 years significantly improved during time, moving from 28% between 2000-2005 to 37% between 2012-2017 (p=0,012). This was related to a significant reduction in RI (45% vs 30%, p<0,0001), whereas NRM remained stable over time (33% vs 35%, p=0,5). The following significant differences were observed across the years of the present study: 1) a longer 5 years OS in patients younger than 65 years (34%) vs those older than 70 years (19%) between 2000 and 2011 only (p=0,003) (Figure 1A and 1B); 2) a longer 5 years OS (p<0.001) and a reduced NRM (p=0.02) for HCT-CI 0 vs 1-2 vs >3 between 2000-2011 only (Figure 2A and 2B); 3) a different 5 years OS according to donor type between 2000 and 2011 only (19% for haplo vs 31% for sibling vs 33% for mismatch UD and 38% for MUD; p<0,0001) (Figure 3A and 3B); 4) a reduction in the incidence of extensive cGVHD at 1 year (15,6% between 2000 and 2005 vs 10,3% between 2012 and 2017, p=0,004) (Figure 4). Comparing 2000-2005 vs 2012-2017, the major significant differences of the patients regard: the baseline disease (more AL/MDS: 40% vs 77%; p<0,001); the disease status at SCT (more CR: 29% vs 54%, p<0,0001), the intensity of conditioning (MAC in 14% vs 42%, p<0,001), the use of alkylator-base conditioning regimen (49% vs 91%; p<0,001) and the use of in vivo T-cell depletion (17% vs 43%, p<0,0001). Moreover, the percentage of patients with HCT-CI > 3 moved from 10% to 30% (p<0,001), in parallel with an increase in patients with KPS 100 (10% vs 30%; p<0,001) By multivariate analysis MUD donor or UCB, no response at the time of SCT and male recipient significantly impaired OS, whereas HCT-CI <1, KPS 90-100 and transplant between 2011-2017 significantly improved OS. These retrospective data showed that the transplant procedure for elderly patients became safer and more effective over time, for a reduction of the RI related to a better selection of patients (more acute leukemias in CR) and a better selection of conditionings (more MAC and more alkylators). Nowdays, the HCT-CI score is probably not sufficient for estimate elderly patients probability of OS and NRM. Figure 1 Figure 1. Disclosures Luppi: Abbvie: Honoraria; Novartis: Honoraria; Sanofi: Honoraria; MSD: Honoraria; Gilead Science: Honoraria, Other: Travel grant; Daiichi-Sankyo: Honoraria; Jazz Pharma: Honoraria. Ciceri: IRCCS Ospedale San Raffaele: Current Employment.

Allogeneic Stem Cell Transplantation Using In Vivo T-Cell Depletion in Myeloid Disorders

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 5451-5451
Author(s):  
Muhammad Ameer Saif ◽  
Maryem Zine ◽  
Andrew Turner ◽  
Helena Lee ◽  
Fiona L Dignan ◽  
...  
Keyword(s):  
Overall Survival ◽  
T Cell ◽  
Graft Rejection ◽  
Peripheral Blood ◽  
Chronic Gvhd ◽  
Conditioning Regimen ◽  
Cell Depletion ◽  
Pcr Analysis ◽  
T Cell Depletion

Abstract Introduction: Alemtuzumab is used for in vivo T-cell depletion to reduce graft versus host disease in allogeneic Stem Cell Transplantation (SCT). Profound lymhotoxicity of this monocloncal antibody can potentially increase morbidity and mortality in SCT due to excessive viral infections and increased risk of graft rejection. We retrospectively analysed outcome of patients with myeloid disorders (acute myeloid leukaemia and myelodysplasia) who received in vivo T-cell depletion using Alemtuzumab based conditioning for allogeneic SCT over a period of 3 years in our centre. Methods: Patients were identified from department transplant data base. Data was collected for 73 consecutive patients over a period of three years using patient medical records, clinical work station and electronic patient records. The conditioning regimen included Fludarabine 30mg/m2 x5 (days -7 to -3), Alemtuzumab 10mgx5 (days -8 to -4) and Melphalan 140mg/m2 (day -2). Chimerism analysis was performed by polymerase chain reaction (PCR) to identify short tandem repeats within peripheral blood leucocytes and CD3 fraction. The quantification of donor chimerism was done by using gel photography system and LabWroks software. Viral testing was performed by PCR analysis. Results: Median age for the patients was 59 years (range 41-71). Median duration of follow up was 19 months (4-49 months). The majority of patients (67%) received SCT from a voluntary unrelated donor. Sixty four patients (88%) had AML whilst 9 had myelodysplasia. Sixty five (89%) patients were in morphological complete remission (<5% blasts) at the time of SCT. Median HCT-Comorbidity index was 2 (range 1-5). Median time to neutrophil engraftment was 13 days (range 9-23) and platelet engraftment 14 days (median 8-48). During the course of transplantation, 50 patients were treated for neutropenic fever with broad spectrum antibiotics and 16 for presumed fungal infection. Forty three patients (59%) reactivated cytomegalovirus (CMV), 10 (13%) had Ebstein Barr Virus (EBV) viremia and 4 (5%) were found to have adenovirus on peripheral blood PCR analysis after SCT. Denovo acute graft versus host disease (grade 2-4) required treatment in 12 patients (16%) whilst chronic GVHD was seen in 14% (n=10). 20 patients required donor lymphocyte infusion due to mixed chimerism after SCT. Total incidence of acute GVHD (grade 2-4) was 23% (n=17) and that of chronic GVHD was 15%. Median donor chimerism in peripheral blood leucocyte fraction was 100% at day 30, 60, 90 and 180 after SCT. Chimerism analysis on CD3 compartment showed 100%, 96%, 95.5% and 95% donor fraction respectively at these time points. Predicted overall survival at 2 years was 53% and Event Free Survival 49%. Non relapsed mortality in this cohort was 18% at one year. One patient had primary graft rejection with no secondary graft rejections. Overall survival was not statistically different between those who were treated for viremia (CMV, EBV, adenovirus) when compared to those who did not have viremia (p=0.31). No deaths were attributed to either CMV or EBV. Conclusion: Our retrospective data show that Alemtuzumab based conditioning regimen in myeloid disorders have low incidence of GVHD, very low risk of graft rejection and comparable overall survival to those conditioning regimens which utilize in vivo T-cell depletion strategies other than Alemtuzumab. Moreover, a high incidence of viremia, in our cohort, did not translate into worse overall survival. Disclosures Saif: Novartis: Honoraria; Alexion: Honoraria. Dignan:Jazz pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Pfizer: Honoraria, Speakers Bureau; Therakos: Honoraria, Speakers Bureau. Tholouli:Jazz Pharmaceuticals: Honoraria, Speakers Bureau; MSD: Honoraria, Speakers Bureau; Pfizer: Honoraria, Speakers Bureau.

Reconstitution of CD52-Negative CD4 T Cells after Alemtuzumab-Based T Cell Depleted Allogeneic Hematopoietic Stem Cell Transplantation

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1182-1182
Author(s):  
Eva M Wagner ◽  
Aline N Lay ◽  
Sina Wenzel ◽  
Timo Schmitt ◽  
Julia Hemmerling ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Lymphocytic Leukemia ◽  
Cell Depletion ◽  
Down Regulation ◽  
T Cell Depletion ◽  
Hematopoietic Stem

Abstract The human CD52 molecule is the target of the monoclonal antibody Alemtuzumab, which is used for treating patients with chemo-refractory chronic lymphocytic leukemia as well as for T cell depletion (TCD) in the context of allogeneic hematopoietic stem cell transplantation (HSCT). The molecule is expressed on the surface of lymphocytes, dendritic cells and to a lesser extent on blood-derived monocytes. Previously, investigators have demonstrated that the surface expression of CD52 on T cells is down-regulated after in vitro incubation with Alemtuzumab. By treating purified human CD4 T cells over 4 hours with 10 μg/mL Alemtuzumab in medium supplemented with 10% human AB serum in vitro, we observed a strong decrease of CD52 expression by flow cytometry with a maximum 3–7 days after incubation. The CD52 down-regulation was also found at weaker intensity on CD8 T cells. From previous studies in chronic lymphocytic leukemia patients, it is known that Alemtuzumab treatment also leads to a down-regulation of CD52 on T cells in vivo. However, similar experiments have not been performed in allogeneic HSCT patients receiving Alemtuzumab in vivo for T cell depletion. We therefore analyzed the expression of CD52 on human peripheral blood mononuclear cells isolated at repeated time points from 22 allogeneic HSCT patients after reduced-intensity conditioning with fludarabine and melphalan and in vivo T cell depletion with Alemtuzumab (100 mg). Half of the patients received prophylactic CD8-depleted donor lymphocyte infusions (DLI) to promote immune reconstitution. By flow cytometry, we observed that the CD52 expression on monocytes, B cells, and natural killer cells remained unaltered after transplantation and was not influenced by the application of DLI. In contrast, the majority of CD4 T cells were CD52-negative (median, 72%) after transplantation and they remained CD52-negative in patients who did not receive DLI throughout the first year after HSCT. The permanent lack of CD52 expression could not be explained by a continuous effect of Alemtuzumab, because earlier studies have shown that the antibody is not present in active plasma concentrations beyond day +60 after HSCT. In contrast, patients receiving CD8-depleted DLI demonstrated a significant increase in the proportion of CD52-positive CD4 T cells. In three of our patients (DLI: n=2, non-DLI: n=1) we analyzed the donor chimerism of CD52-positive and CD52-negative CD4 T cells sorted with high purity by flow cytometry. Three months after HSCT (before DLI), the proportion of donor T cells was clearly higher among the CD52-negative compared to the small proportion of CD52-positive cells in all patients (44% vs. 10%, 83% vs. 0%, and 100% vs. 40%). In the patient who did not receive DLI, the donor T cell chimerism remained mixed in the CD52-negative and CD52-positive fractions on days 200 (CD52-negative: 95%; CD52-positive: 15%) and 350 (CD52-negative: 92%; CD52-positive: 65%). In contrast, the two patients receiving CD8-depleted DLI showed a strong increase in the proportion of CD52-positive CD4 T cells that were of complete donor origin. Altogether, CD52 is permanently down-regulated in reconstituting CD4 T cells following HSCT with an Alemtuzumab-based TCD regimen unless DLI are applied. Our data support the idea of an active mechanism for CD52 down-regulation in CD4 T cells that is not related to B cells and natural killer cells and that appears to differently affect donor and host T cells, respectively.

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