CMV Immunity Status in Older (>50 Years Old) Subjects after Non-Myeloablative or Reduced Intensity Regimen for Hematopoietic Cell Transplantation (HCT): A Comparison with a Younger Cohort after Ablative HCT.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3246-3246
Author(s):  
Ghislaine Gallez-Hawkins ◽  
Lia Thao ◽  
Simon F. Lacey2 ◽  
Joybelle Martinez ◽  
Anne E. Franck ◽  
...  
Keyword(s):  
Immune Response ◽  
Stem Cell ◽  
T Cell ◽  
Cell Transplantation ◽  
Immune Reconstitution ◽  
Cmv Infection ◽  
Cd8 Cells ◽  
Group 2 ◽  
Reduced Intensity ◽  
Group 1

Abstract Immunity declines with age as demonstrated by cell-mediated and humoral responses to alloantigens. The susceptibility of these elderly subjects to endogenous virus infection, such as human cytomegalovirus (HCMV) reactivation, is a particular concern during the process of hematopoietic stem cell transplantation (HCT) and immune reconstitution. In this report, the host contribution to stem cell engraftment and differentiation was evaluated by comparing the HCMV immune response in older subjects (> 50 y.o.) to a younger (< 50 y.o.) transplant population. This was a retrospective analysis of a subset of data collected prospectively and with IRB approval for characterization of the CMV immune response of allogeneic transplant patients. Within the dataset, two groups of patients were compared. Group 1 consisted of 10 patients >50 y.o. who had received reduced intensity or non-myeloablative conditioning regimen, and Group 2 consisted of 13 patients <50 y.o., most of whom had received a myeloablative regimen. Because 9 of 10 in Group 1 had had CMV reactivation, Group 2 was selected from the subset of younger patients with known post-transplant CMV infection. CMV infection was defined as either a positive CMV blood culture using shell vial assay or a positive CMV PCR on plasma. Subjects were assessed on days 40, 90, 120, 150, 180, and 360 post-HCT by CMV-specific tetramer-binding assay using CD8 cells, assays for intracellular INF-g response of CD4 and CD8 cells, and a T-cell receptor excision circle (TREC) assay. There were no significant differences observed in the CD4+/IFN-g+ cell responses to CMV antigen nor were the rates of activated CD4+/CD69+/IFN-g+ cells different between the groups. Group 1 was also characterized by a robust CD8+/IFN-g+ response to HLA-specific CMV peptides, and all subjects had ≥ 2cells/μl by day 150 post-HCT. The frequency of CMV tetramer positive cells (≥ 2cells/μl) was 50% in Group 1 by day 90 post-HCT and was not statistically different from Group 2. The T cell renewal in the thymus as measured by the TREC spanned over 0 -- 92 copies/μg of total cellular DNA in Group 1 and from 0 – 129 copies/μg in Group 2 during the first year post-HCT (n.s.). In conclusion, CMV immune reconstitution in older transplant subjects, who undergo a reduced intensity or non-myeloablative regimen, is robust and, in this small sampling, did not differ from that observed in a younger adult group.

scholarly journals CMV Infection and CMV-Specific Immune Reconstitution Following Haploidentical Stem Cell Transplantation: An Update

2021 ◽  
Vol 12 ◽  
Author(s):  
Xiao-Hua Luo ◽  
Yan Zhu ◽  
Yu-Ting Chen ◽  
Li-Ping Shui ◽  
Lin Liu
Keyword(s):  
Stem Cell ◽  
T Cell ◽  
Stem Cell Transplantation ◽  
Cell Transplantation ◽  
Immune Reconstitution ◽  
Ex Vivo ◽  
Cellular Immunotherapy ◽  
Cmv Infection ◽  
Haploidentical Stem Cell Transplantation

Haploidentical stem cell transplantation (haploSCT) has advanced to a common procedure for treating patients with hematological malignancies and immunodeficiency diseases. However, cure is seriously hampered by cytomegalovirus (CMV) infections and delayed immune reconstitution for the majority of haploidentical transplant recipients compared to HLA-matched stem cell transplantation. Three major approaches, including in vivo T-cell depletion (TCD) using antithymocyte globulin for haploSCT (in vivo TCD-haploSCT), ex vivo TCD using CD34 + positive selection for haploSCT (ex vivo TCD-haploSCT), and T-cell replete haploSCT using posttransplant cyclophosphamide (PTCy-haploSCT), are currently used worldwide. We provide an update on CMV infection and CMV-specific immune recovery in this fast-evolving field. The progress made in cellular immunotherapy of CMV infection after haploSCT is also addressed. Groundwork has been prepared for the creation of personalized avenues to enhance immune reconstitution and decrease the incidence of CMV infection after haploSCT.

scholarly journals High Graft CD8 Cell Dose Predicts Improved Survival and Enables Better Donor Selection in Allogeneic Stem-Cell Transplantation With Reduced-Intensity Conditioning

2015 ◽  
Vol 33 (21) ◽  
pp. 2392-2398 ◽  
Author(s):  
Ran Reshef ◽  
Austin P. Huffman ◽  
Amy Gao ◽  
Marlise R. Luskin ◽  
Noelle V. Frey ◽  
...  
Keyword(s):  
Overall Survival ◽  
Stem Cell ◽  
T Cell ◽  
Stem Cell Transplantation ◽  
Cell Transplantation ◽  
Unrelated Donor ◽  
Cd8 Cells ◽  
Cd8 Cell ◽  
The Impact ◽  
Reduced Intensity

Purpose To characterize the impact of graft T-cell composition on outcomes of reduced-intensity conditioned (RIC) allogeneic hematopoietic stem-cell transplantation (alloHSCT) in adults with hematologic malignancies. Patients and Methods We evaluated associations between graft T-cell doses and outcomes in 200 patients who underwent RIC alloHSCT with a peripheral blood stem-cell graft. We then studied 21 alloHSCT donors to identify predictors of optimal graft T-cell content. Results Higher CD8 cell doses were associated with a lower risk for relapse (adjusted hazard ratio [aHR], 0.43; P = .009) and improved relapse-free survival (aHR, 0.50; P = .006) and overall survival (aHR, 0.57; P = .04) without a significant increase in graft-versus-host disease or nonrelapse mortality. A cutoff level of 0.72 × 108 CD8 cells per kilogram optimally segregated patients receiving CD8hi and CD8lo grafts with differing overall survival (P = .007). Donor age inversely correlated with graft CD8 dose. Consequently, older donors were unlikely to provide a CD8hi graft, whereas approximately half of younger donors provided CD8hi grafts. Compared with recipients of older sibling donor grafts (consistently containing CD8lo doses), survival was significantly better for recipients of younger unrelated donor grafts with CD8hi doses (P = .03), but not for recipients of younger unrelated donor CD8lo grafts (P = .28). In addition, graft CD8 content could be predicted by measuring the proportion of CD8 cells in a screening blood sample from stem-cell donors. Conclusion Higher graft CD8 dose, which was restricted to young donors, predicted better survival in patients undergoing RIC alloHSCT.

CD8-Depleted Donor Lymphocyte Infusions Can Boost Immune Reconstitution after Haploidentical Stem Cell Transplantation Following Reduced-Intensity Conditioning Regimen.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3138-3138 ◽  
Author(s):  
Paolo Corradini ◽  
Anna Raganato ◽  
Cristiana Carniti ◽  
Matteo Carrabba ◽  
Farina Lucia ◽  
...  
Keyword(s):  
Stem Cell ◽  
T Cell ◽  
High Risk ◽  
Stem Cell Transplantation ◽  
Cell Transplantation ◽  
Immune Reconstitution ◽  
Acute Gvhd ◽  
Mean Value ◽  
Reduced Intensity Conditioning ◽  
Reduced Intensity

Abstract Haploidentical stem cell transplantation (SCT) can be used in relapsed haematological malignancies for patients lacking a matched sibling or unrelated donor. Major barriers of this strategy are the poor immune reconstitution and the high risk of relapse. Here, we report results of a phase I–II trial evaluating early add-backs of CD8-depleted donor lymphocytes (DLIs) (from 1x10^4 up to 1x10^5 cells/kg starting at day+45 up to day +105 at monthly intervals) after a reduced intensity conditioning (RIC) regimen [thiotepa (10 mg/kg), fludarabine (120 mg/sqm), cyclophosphamide (60 mg/kg) and TBI (2 Gy)]. Ex-vivo and in-vivo TCD were carried out by CD34+ cell selection using the CliniMACS device and alemtuzumab (15mg/m2, day-2), respectively. Twenty-one patients [n= 10 NHL (n=5 CLL, n=5 high-grade NHL), n=7 HL, n=1 MM, n=1 ALL, n=2 AML] were transplanted with advanced disease: 16 (76%) failed a previous autograft and 13 (62%) had refractory disease. A median of 10.4x10^6/Kg CD34+, 1x10^4/kg CD3+, 10x10^4/kg CD19+, 0.9 x10^4/kg NK+ were infused. All patients engrafted with full donor chimerism from day +90. At a median follow-up of 12 months (range, 4–41 months), 12 of 21 pts are alive (7 CR, 2 PR and 3 PD) and 9 died [n=3 infection with GVHD (+610, +187, +253), n=6 disease]. The estimated 2-year overall survival was 49%: pts transplanted in remission had better outcome (83% versus 31%, p=0.13). The estimated 2-year cumulative incidence of TRM and relapse were 27% and 58%, respectively. CMV reactivation and hospital readmissions for opportunistic infections occurred in 76% and 57% of patients, respectively. For CD8 depletion of donor leukaphereses, a new depletion protocol using clinical grade CD8 microbeads (Miltenyi) was applied. This procedure is efficient to reduce the content of CD8 T cells by 3 logs while the median cell recovery of CD3+, CD4+, CD56+/CD3+, CD 20+ was 60%, 86%, 54%, 72%, respectively. Before DLIs, only 2 of 21 patients (10%) developed acute GVHD (no grade III–IV). A total of 36 CD8-depleted DLIs were administered to 17 pts without any acute toxicity. Following DLIs, 6 pts (35%) developed acute GVHD (grade II) and 5 (30%) chronic GVHD (n=2 limited, n=3 extensive). Overall, the incidence of acute GVHD is higher (50% vs 22%, p=0.33) in pts receving larger numbers of donor cells (10–15x10^4/kg versus 3–5x10^4/kg CD8-depleted DLIs). The median values of CD4+/uL, CD8+/uL and NK+ were 100, 280 and 680 at 4 months and 220, 200, 500 at 6 months after SCT in patients receiving CD8-depleted DLIs. Measurable TREC/ucg DNA (mean value 316; mean value donors 3740) and polyclonal T cell repertoire, evaluated by spectratyping, were observed at 9 months in patients younger than 40 years and/or without GVHD. Our results suggest that: haploidentical SCT with RIC regimen provides high engraftment rate T-cell addback allows the achievement of more than 100/uL CD4+ at 4 months after SCT in the majority of patients Survival rate is promising in patients who had transplantation in remission suggesting that this strategy should be evaluated earlier in high risk haematological diseases.

Imaging the Differential Engraftment of GFP-Expressing Spleen and Bone Marrow Cells in Various Organs after Reduced-Intensity Stem Cell Transplantation in Mice Model.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3228-3228
Author(s):  
Yuji Heike ◽  
Zhijian Yang ◽  
Huaiyu Ma ◽  
Robert Hoffmann ◽  
Yuriko Morita ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Stem Cell Transplantation ◽  
Cell Transplantation ◽  
Pelvic Bone ◽  
Donor Cells ◽  
Cd34 Cells ◽  
Group 2 ◽  
Reduced Intensity ◽  
Group 1

Abstract [Background] Reduced-intensity allogeneic stem cell transplantation is of critical importance in the treatment of hematological malignancies. The object of this experiment is to establish fludrabine-based reduced-intensity allogeneic stem cell transplantation model using donor cells labeled with GFP and image the engraftment process of donor cells in various organs. [Materials and Methods] GFP transgenic C57/BL6 mice (GFP-Tgm) were used as donors and C57/BL6 × DBA F1 mice (BDF1) were used as recipients. Recipient mice were pretreated with fludarabine (Flu) 150 mg/kg/day × 6 days i.p. and cyclophosphamide (CPA) 150 mg/kg/day × 2 days i.p. On day 0, 107 GFP splenocytes (Group 1) and GFP bone marrow cells (Group 2) were injected in the tail vein. Whole body and intravital imaging were used to visualize the migration of GFP-Tgm cells into various organs including the brain, femur, intestine, liver, lung, ovary, pelvic bone, ribs, skin, skull, spine, spleen and uterus on days-7 and -14. The macro images were obtained with the Olympus OV100 Small Animal Imaging System. GFP-Tgm cell migration, particularly CD34+ cells in the various organs was also analyzed by flow cytometry (FACS) using APC-labeled anti-CD34 monoclonal antibodies. [Results and Discussion] On day-7, the migration of donor GFP-Tgm cells in peripheral lymph nodes, intestine, lung, ovary, skin and uterus were detected in both groups. Migration of GFP-Tgm cells in the femur, pelvic bone, ribs and skull were clearly detected in Group 2, but not in Group 1. On day-14 GFP donor cells were imaged in the lung, ovary, skin and uterus both groups. However, GFP-Tgm cells were no longer imaged in the intestine in Group 2 except in Payer patches. In both groups the GFP-Tgm cells were strongly detected in the femur, pelvic bone, skull and spine on day-14. We also analyzed the migration of CD34+ GFP-Tgm cells by FACS analysis. On day-14, the percentage of GFP-Tgm cells in the bone marrow and spleen was, respectively, 14% and 53% in Group 1, and 10% and 13% in Group 2. The percentage of CD34+ GFP-Tgm cells among total CD34+ cells in the bone marrow was 10% in Group 1 and 14% in Group 2, and in the spleen was 24% and 19%, respectively. Those results suggested that in this model, donor bone marrow and spleen cells, but not purified CD34+ cells, have different engraftment kinetics in various organs including the intestine, which is a target organ for graft-versus host disease. These results clearly suggest that caution should be paid to evaluate engraftment kinetics of infused cells, at least in mice model.

Full Haplotype Mismatch Stem Cell Transplantation: Myeloablative with T-Cell Depletion Vs. Reduced Intensity Conditioning without T-Cell Depletion

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3533-3533 ◽  
Author(s):  
Heeje Kim ◽  
Woo-Sung Min ◽  
Ki-Seong Eom ◽  
Byung-Sik Cho ◽  
Seung-Ah Yahng ◽  
...  
Keyword(s):  
Stem Cell ◽  
T Cell ◽  
High Risk ◽  
Cell Depletion ◽  
Reduced Intensity Conditioning ◽  
T Cell Depletion ◽  
Group 2 ◽  
Reduced Intensity ◽  
Group 1

Abstract Abstract 3533 Some groups have continuously tried to reveal the possible role of full-haplotype mismatch stem cell transplantation (SCT) in patients who lack a compatible donor. However, the long-term event-free survival (EFS) rate after high-grade mismatch SCT using conventional myeloablative conditioning with T-cell depletion (TCD), even in complete remission (CR), is still only in the range of 10–30%. Most patients who were transplanted had heavily pretreated acute leukemia. The most important obstacle to overcome is the high rate of infection-related mortality associated with delayed immunological recovery in the setting of full-haplotype mismatch SCT, specifically by way of complete depletion of donor T cells in the graft. In contrast, by using unmanipulated donor cells and less aggressive conditioning regimens without TCD, most groups in Asia have reported EFS >40%. We investigated the role of reduced-intensity conditioning without TCD in HLA-mismatched related-donor SCT, specifically in patients with high-risk acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) who received unmanipulated granulocyte colony stimulating factor (G-CSF)-mobilized peripheral blood stem cells (PBSCs). SCT was performed in 32 consecutive patients. We compared two different protocols: one with more intensive conventional conditioning with TCD (group 1), and one with reduced intensity without TCD (group 2). The protocols differed between the two groups with respect to total body irradiation (1200 cGy in group 1 vs. 800 cGy in group 2) as well as busulfex, fludarabine, and anti-thymocyte globulin (ATG; thymoglobulin, Genzyme) treatments. No patient in group 1 received post-transplant graft versus host disease (GvHD) prophlyaxis or G-CSF. In contrast, all patients in group 2 received 1.25 mg/kg/day ATG for 4 consecutive days, together with our standard GvHD prophylaxis regimen of methotrexate (5 mg/m2 intravenous bolus on days 1, 3, 6, and 11) and tacrolimus starting at day –1. All patients received G-CSF-mobilized PBSCs. The median number of CD34+ cells infused was 14.2 (range, 4.3–20.6) × 106/kg for group 1 and 6.0 (range, 3.6–8.5) × 106/kg for group 2. The median numbers of CD3+ cells infused were 0.03 (range, 0.015–0.057) × 106/kg and 870 (range, 84–1260) × 106/kg, respectively. G-CSF was administered subcutaneously to all patients in group 2 at a dose of 5 mg/kg/day, from day 7 after transplantation until neutrophil recovery. GvHD, relapse, non-relapse mortality (NRM), overall survival, EFS, reconstitution of immunity, and natural killer (NK) cell alloreactivity were compared between the groups. The median patient age was 33 (range, 17–48) years for group 1 and 39 (range, 19–63) years for group 2. The median follow-up for surviving patients was 18 months (range, 8–100). The majority of patients had intermediate or unfavorable cytogenetic features. The transplanted patients were all successfully engrafted. The median times to neutrophil (>0.5 × 109/kg) and platelet (>20 × 109/kg) recovery were 12 and 13 days in group 1, and 11 and 10 days in group 2. The overall rates of acute and chronic GvHD were 50% and 33%, and 80% and 92% in groups 1 and 2, respectively. Of note, NRM differed significantly between the groups: 46.2% in group 1 vs. 9.5% in group 2 (P = 0.0014). The estimated probability of EFS at 2 years was 15.3% for group 1 vs. 59.2% for group 2 (P = 0.05). We did not find NK alloreactivity in any of the patients, based on the NK-killer cell immunoglobulin-like receptor (KIR) disparity between donor and recipient. However, we noted a significant difference in EFS between C1/C1 homozygotes and C1/C2 heterozygotes according to the donor NK-KIR ligands (P = 0.0175). Recovery of CD4+ cell numbers at 3 months after SCT showed a markedly different pattern between the groups, with a median of 4 cells/μl (range, 2–7) in group 1 vs. 311 cells/μl (range, 56–1226) in group 2. Our findings suggest that full-haplotype mismatch SCT using a Korean-adapted protocol is a feasible therapeutic strategy for patients with high-risk AML/MDS, specifically in CR, provided that there is a further defined plan for the investigation of NK/T-cell alloreactivity. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Improving Cytomegalovirus-Specific T Cell Reconstitution after Haploidentical Stem Cell Transplantation

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Xiao-Hua Luo ◽  
Ying-Jun Chang ◽  
Xiao-Jun Huang
Keyword(s):  
Stem Cell ◽  
T Cell ◽  
Stem Cell Transplantation ◽  
Cell Transplantation ◽  
Cmv Infection ◽  
Graft Versus Host ◽  
Stem Cell Source ◽  
Haploidentical Stem Cell Transplantation ◽  
Donor T Cells ◽  
Conditioning Regimens

Cytomegalovirus (CMV) infection and delayed immune reconstitution (IR) remain serious obstacles for successful haploidentical stem cell transplantation (haplo-SCT). CMV-specific IR varied according to whether patients received manipulated/unmanipulated grafts or myeloablative/reduced intensity conditioning. CMV infection commonly occurs following impaired IR of T cell and its subsets. Here, we discuss the factors that influence IR based on currently available evidence. Adoptive transfer of donor T cells to improve CMV-specific IR is discussed. One should choose grafts from CMV-positive donors for transplant into CMV-positive recipients (D+/R+) because this will result in better IR than would grafts from CMV-negative donors (D−/R+). Stem cell source and donor age are other important factors. Posttransplant complications, including graft-versus-host disease and CMV infection, as well as their associated treatments, should also be considered. The effects of varying degrees of HLA disparity and conditioning regimens are more controversial. As many of these factors and strategies are considered in the setting of haplo-SCT, it is anticipated that haplo-SCT will continue to advance, further expanding our understanding of IR and CMV infection.

scholarly journals Association between preconditioning absolute lymphocyte count and transplant outcomes in patients undergoing matched unrelated donor allogeneic hematopoietic stem cell transplantation with reduced-intensity conditioning and anti-thymocyte globulin

2021 ◽  
Vol 12 ◽  
pp. 204062072110637
Author(s):  
Jeongmin Seo ◽  
Dong-Yeop Shin ◽  
Youngil Koh ◽  
Inho Kim ◽  
Sung-Soo Yoon ◽  
...  
Keyword(s):  
Stem Cell ◽  
T Cell ◽  
Stem Cell Transplantation ◽  
Cell Transplantation ◽  
Cell Depletion ◽  
Unrelated Donor ◽  
Reduced Intensity Conditioning ◽  
Matched Unrelated Donor ◽  
T Cell Depletion ◽  
Reduced Intensity

Background: Allogeneic stem cell transplantation (alloSCT) offers cure chance for various hematologic malignancies, but graft- versus-host disease (GVHD) remains a major impediment. Anti-thymocyte globulin (ATG) is used for prophylactic T-cell depletion and GVHD prevention, but there are no clear guidelines for the optimal dosing of ATG. It is suspected that for patients with low absolute lymphocyte counts (ALCs), current weight-based dosing of ATG can be excessive, which can result in profound T-cell depletion and poor transplant outcome. Methods: The objective of the study is to evaluate the association of low preconditioning ALC with outcomes in patients undergoing matched unrelated donor (MUD) alloSCT with reduced-intensity conditioning (RIC) and ATG. We conducted a single-center retrospective longitudinal cohort study of acute leukemia and myelodysplastic syndrome patients over 18 years old undergoing alloSCT. In total, 64 patients were included and dichotomized into lower ALC and higher ALC groups with the cutoff of 500/μl on D-7. Results: Patients with preconditioning ALC <500/μl were associated with shorter overall survival (OS) and higher infectious mortality. The incidence of acute GVHD and moderate-severe chronic GVHD as well as relapse rates did not differ according to preconditioning ALC. In multivariate analyses, low preconditioning ALC was recognized as an independent adverse prognostic factor for OS. Conclusion: Patients with lower ALC are exposed to excessive dose of ATG, leading to profound T-cell depletion that results in higher infectious mortality and shorter OS. Our results call for the implementation of more creative dosing regimens for patients with low preconditioning ALC.

New Developments in Allotransplant Immunology

Hematology ◽  
2003 ◽  
Vol 2003 (1) ◽  
pp. 350-371 ◽  
Author(s):  
A. John Barrett ◽  
Katayoun Rezvani ◽  
Scott Solomon ◽  
Anne M. Dickinson ◽  
Xiao N. Wang ◽  
...  
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
T Cell ◽  
Stem Cell Transplantation ◽  
Cell Transplantation ◽  
Immune Reconstitution ◽  
Cytokine Gene ◽  
Post Transplant ◽  
Cytokine Milieu ◽  
Cytokine Gene Polymorphisms

Abstract After allogeneic stem cell transplantation, the establishment of the donor’s immune system in an antigenically distinct recipient confers a therapeutic graft-versus-malignancy effect, but also causes graft-versus-host disease (GVHD) and protracted immune dysfunction. In the last decade, a molecular-level description of alloimmune interactions and the process of immune recovery leading to tolerance has emerged. Here, new developments in understanding alloresponses, genetic factors that modify them, and strategies to control immune reconstitution are described. In Section I, Dr. John Barrett and colleagues describe the cellular and molecular basis of the alloresponse and the mechanisms underlying the three major outcomes of engraftment, GVHD and the graft-versus-leukemia (GVL) effect. Increasing knowledge of leukemia-restricted antigens suggests ways to separate GVHD and GVL. Recent findings highlight a central role of hematopoietic-derived antigen-presenting cells in the initiation of GVHD and distinct properties of natural killer (NK) cell alloreactivity in engraftment and GVL that are of therapeutic importance. Finally, a detailed map of cellular immune recovery post-transplant is emerging which highlights the importance of post-thymic lymphocytes in determining outcome in the critical first few months following stem cell transplantation. Factors that modify immune reconstitution include immunosuppression, GVHD, the cytokine milieu and poorly-defined homeostatic mechanisms which encourage irregular T cell expansions driven by immunodominant T cell–antigen interactions. In Section II, Prof. Anne Dickinson and colleagues describe genetic polymorphisms outside the human leukocyte antigen (HLA) system that determine the nature of immune reconstitution after allogeneic stem cell transplantation (SCT) and thereby affect transplant outcomethrough GVHD, GVL, and transplant-related mortality. Polymorphisms in cytokine gene promotors and other less characterized genes affect the cytokine milieu of the recipient and the immune reactivity of the donor. Some cytokine gene polymorphisms are significantly associated with transplant outcome. Other non-HLA genes strongly affecting alloresponses code for minor histocompatibility antigens (mHA). Differences between donor and recipient mHA cause GVHD or GVL reactions or graft rejection. Both cytokine gene polymorphisms (CGP) and mHA differences resulting on donor-recipient incompatibilities can be jointly assessed in the skin explant assay as a functional way to select the most suitable donor or the best transplant approach for the recipient. In Section III, Dr. Nelson Chao describes non-pharmaceutical techniques to control immune reconstitution post-transplant. T cells stimulated by host alloantigens can be distinguished from resting T cells by the expression of a variety of activation markers (IL-2 receptor, FAS, CD69, CD71) and by an increased photosensitivity to rhodamine dyes. These differences form the basis for eliminating GVHD-reactive T cells in vitro while conserving GVL and anti-viral immunity. Other attempts to control immune reactions post-transplant include the insertion of suicide genes into the transplanted T cells for effective termination of GVHD reactions, the removal of CD62 ligand expressing cells, and the modulation of T cell reactivity by favoring Th2, Tc2 lymphocyte subset expansion. These technologies could eliminate GVHD while preserving T cell responses to leukemia and reactivating viruses.

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