scholarly journals The Proportion of CD52/GPI Negative T Cells Early Following Alemtuzumab Conditioned Haematopoetic Stem Cell Transplantation Is an Independent Risk Factor for Acute GvHD

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4543-4543
Author(s):  
Francesca Kinsella ◽  
Charlotte F Inman ◽  
Duncan Murray ◽  
Wayne Croft ◽  
Jianmin Zuo ◽  
...  

T cell depletion with in vivo alemtuzumab is used to ameliorate the graft versus host response and permit donor engraftment in allogeneic haematopoietic stem cell transplantation (allo-HSCT). Previous reports have shown that T cells lacking CD52 are often detectable during the period of early immune reconstitution with this protocol, but the clinical relevance of this cellular population is not understood. In a cohort of 67 consecutive patients undergoing allo-HSCT between 2013-2016 we investigated the phenotype and function of the CD52-negative T cell fraction and related their presence to clinical outcome. 47 patients (70%) had a myeloid disease (AML or MDS) while 20 patients had lymphoid disease. All patients received in vivo alemtuzumab (10mg/day from day -5 for 5 days). 63 (94%) received reduced intensity conditioning chemotherapy, while 4 (6%) received a myeloablative regimen. All patients received post-transplant ciclosporin A for GvHD prophylaxis. 6 (9%) also received methotrexate, while 2 (3%) patients also received mycophenolate mofetil. Overall survival at 2 years was 68% and relapse free survival was 48%. 29% patients experienced acute GvHD (grade 2 or above) and 15% developed chronic GvHD. CD52-negative T cells demonstrated low binding of FLAER, indicating downregulation of the glycophosphatidylinositol (GPI) anchor, although we did not detect any mutations in the PIG-A gene as is typically seen in patients with PNH. CD52-negative T cells were almost exclusively CD4+ and exhibited a dominant memory phenotype with only small numbers of CD25+ CD127lowFoxp3+ regulatory T cells. They exhibited enhanced cytotoxic responses to T cell receptor stimulation in vitro. Early after allo-HSCT, the presence of a significant population of CD52 negative T cells (comprising >51% of the T cell fraction) was found to be an independent risk factor for acute GvHD. This was confirmed in a validation cohort of 28 patients obtained between 2017-2018. These data suggest that CD52/GPI-negative T cells arise from the selective pressure of alemtuzumab in the setting of lymphopenia and homeostatic proliferation. To our knowledge this is the first study to show that CD52 negative T cells have a reduced regulatory T cell fraction, and have an association with acute GvHD. This suggests that the CD52-negative T cell fraction may represent a 'footprint' of the early alloreactive response focused within the CD4+ population, or contribute to an immune environment with reduced T cell tolerance. These data help to delineate the nature of T cell escape from alemtuzumab surveillance providing new insights into the early alloreactive immune response. Furthermore, this study informs the use of alemtuzumab in conditioning regimens for upcoming cellular immunotherapies. Disclosures No relevant conflicts of interest to declare.

2022 ◽  
Vol 11 (1) ◽  
pp. 270
Author(s):  
Martina Hinterleitner ◽  
Clemens Hinterleitner ◽  
Elke Malenke ◽  
Birgit Federmann ◽  
Ursula Holzer ◽  
...  

Immune cell reconstitution after stem cell transplantation is allocated over several stages. Whereas cells mediating innate immunity recover rapidly, adaptive immune cells, including T and B cells, recover slowly over several months. In this study we investigated kinetics and reconstitution of de novo B cell formation in patients receiving CD3 and CD19 depleted haploidentical stem cell transplantation with additional in vivo T cell depletion with monoclonal anti-CD3 antibody. This model enables a detailed in vivo evaluation of hierarchy and attribution of defined lymphocyte populations without skewing by mTOR- or NFAT-inhibitors. As expected CD3+ T cells and their subsets had delayed reconstitution (<100 cells/μL at day +90). Well defined CD19+ B lymphocytes of naïve and memory phenotype were detected at day +60. Remarkably, we observed a very early reconstitution of antibody-secreting cells (ASC) at day +14. These ASC carried the HLA-haplotype of the donor and secreted the isotypes IgM and IgA more prevalent than IgG. They correlated with a population of CD19− CD27− CD38low/+ CD138− cells. Of note, reconstitution of this ASC occurred without detectable circulating T cells and before increase of BAFF or other B cell stimulating factors. In summary, we describe a rapid reconstitution of peripheral blood ASC after CD3 and CD19 depleted haploidentical stem cell transplantation, far preceding detection of naïve and memory type B cells. Incidence before T cell reconstitution and spontaneous secretion of immunoglobulins allocate these early ASC to innate immunity, eventually maintaining natural antibody levels.


Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4662-4662
Author(s):  
Masoud Manjili ◽  
Catherine H Roberts ◽  
Maciej Kmieciak ◽  
Madhu S Gowda ◽  
Andrea Ferreira-Gonzalez ◽  
...  

Abstract Abstract 4662 Patients undergoing unrelated donor stem cell transplantation following reduced intensity regimens are prone to acute graft vs host disease (GVHD). In vivo T cell depletion with rabbit anti-thymocyte globulin (r-ATG, Thymoglobulin, Genzyme inc. Cambridge MA) is consistently associated with reduced risk of acute GVHD however poor T cell reconstitution seen with current schedules results in a high incidence of opportunistic infections and relapse. We report data on immune reconstitution in patients participating in an ongoing clinical trial testing a novel conditioning regimen for allogeneic GCSF-mobilized blood stem cell transplantation. Patients were randomized to receive conditioning with either 7.5 or 5.1 mg/kg of r-ATG in divided doses between days -9 and -7, followed by 450 cGy total body irrradiation (TBI) in 3 fractions on day -1 and 0. GVHD prophylaxis was with tacrolimus (day -3 to 120) and mycophenolate mofetil (day 0-30). So far 10 heavily pre-treated (median number of prior therapies 4, prior autologous SCT n=5) patients have been transplanted; 6 from unrelated donors (1 bone marrow), 3 from matched related donors and 1 from an HLA-A mismatched sibling. Diagnosis includes MM (4), NHL (3), and CLL/PLL (3). Median patient age is 57 years. No patients have developed acute GVHD in the first 90 days. All patients achieved prompt engraftment of neutrophils and have demonstrated sustained complete myeloid donor chimerism (median <1% recipient DNA) at 3-6 months post transplant. NK cell recovery is prompt (mean±SD absolute CD56+ cell count 177±85/μL at day 30) and sustained (184±116 at day 90). T cell subset recovery is modest (absolute CD3+ cell count 861±934/μL at day 90) with predominantly cytotoxic T cells (CD3+/4+ cell count 143±116 and CD3+/8+ cell count 708±837). T cell chimerism at day 90 is mixed with either donor ('10% recipient DNA, n=5) or recipient dominance (>10% recipient DNA, n=3). Patients demonstrating dominant donor T cell chimerism at day 90 went on to develop either delayed onset acute GVHD (n=2/8 evaluable) or chronic GVHD (n=2/8) after withdrawal of immunosuppression. Patients demonstrating mixed T cell chimerism with recipient dominance did not develop chronic GVHD; one of these patients has relapsed, following an HLA-A mismatched SCT from his brother, and though he had predominantly recipient derived T cells, his granulocytes were completely donor derived indicating graft tolerance. T cell receptor beta locus was examined by RT-PCR for oligoclonality in all the donor-recipient pairs at baseline, day 90 and at onset of GVHD. Patients with GVHD demonstrated high level of expression of TCR V beta 23 and 24 (n=1/4), 11 (n= 1/4), 18 (n= 1/4), or 11 and 18 (n= 1/4) exclusively, in addition to TCR V beta 14, 16, 17, 22. The latter loci were also expressed in patients who had no GVHD with mixed T cell chimerism; this group of patients also expressed TCR V beta 4 (n=2/2), 13 and 19 (n=1/2) exclusively. All but one of the patients expressed the majority of TCR V beta loci at day 90 (with the exceptions noted above) indicating early polyclonal T cell recovery following transplantation. Asymptomatic CMV and EBV reactivation requiring therapy developed in one patient each. No patients have developed invasive fungal infections. In conclusion conditioning with Thymoglobulin and reduced intensity TBI results in stable myeloid engraftment in patients receiving unrelated and alternative donor transplants. In this small group of patients, GVHD appears to be associated with emergence of oligoclonal T cell populations which in the future may be selectively depleted ex vivo to allow engraftment without risk of chronic GVHD. Disclosures: McCarty: Celgene: Honoraria; Genzyme: Honoraria. Toor:Genzyme: Research Funding.


Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 5435-5435
Author(s):  
Rimke Oostvogels ◽  
Rieuwert Hoppes ◽  
Henk Lokhorst ◽  
Robbert M Spaapen ◽  
Huib Ovaa ◽  
...  

Abstract Allogeneic stem cell transplantation (allo-SCT), alone or followed by donor lymphocyte infusion (DLI), is a potentially curative treatment for various hematological malignancies. In an HLA-matched transplantation setting, the therapeutic graft-versus-tumor (GvT) effect is mediated by donor T-cells directed at minor histocompatibility antigens (mHags), which are HLA-bound polymorphic peptides. Unfortunately, most patients don’t achieve complete response or relapse after allogeneic stem cell transplantation and thus still require additional therapies. Immunotherapy aimed at hematopoietically restricted mHags could theoretically provide an ideal method to augment the GvT effect, without causing GvHD. The most relevant mHags for immunotherapy are those antigens that are only expressed on hematopoietic tissue, are presented by frequent HLA molecules and display an equally balanced population frequency. UTA2-1 and HA-1 are two of these most broadly applicable mHags identified up until now and are therefore included in on-going clinical trials of mHag-peptide loaded dendritic cell vaccination in patients with various hematological malignancies. Another method for mHag-based immunotherapy could be adoptive transfer of ex vivo cultured mHag-specific cytotoxic T lymphocytes (CTL). However, initial results of both methods, also from preclinical models and trials in patients with solid tumors, postulate the necessity for improved strategies for efficient ex vivo and in vivo induction of tumour specific CTLs. We here show for the HLA-A*02 restricted epitopes UTA2-1 and HA-1 that their MHC binding and consequent T cell reactivity can be improved through the incorporation of certain newly designed non-proteogenic amino acids at crucial MHC anchoring positions. With this novel approach we designed superior altered peptide ligands (APLs) for both epitopes, of which the best modifications not only increased MHC binding and stability, but also improved recognition by antigen specific T cells. Most importantly, these optimised peptides gave rise to superior antitumor T cell responses in vitro and in vivo in comparison to the native epitope, as they induced significantly enhanced proliferation of peptide-specific T cells with retained cytotoxic potential against malignant targets expressing the natural UTA2-1 antigen. Hence, these APLs designed with non-proteogenic amino acids with enhanced MHC-affinity and immunogenicity may improve the therapeutic outcome of mHag-based vaccination strategies, or can be utilized for ex vivo antigen-specific T cell enrichment and expansion for transfer into patients with haematological malignancies. Disclosures: Lokhorst: Genmab A/S: Consultancy, Research Funding; Celgene: Honoraria; Johnson-Cilag: Honoraria; Mudipharma: Honoraria.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3205-3205
Author(s):  
Ralf G. Meyer ◽  
Shahrzad Bakhtiar ◽  
Klaus Bender ◽  
Timo Schmitt ◽  
Abdo Konur ◽  
...  

Abstract Early acute GVHD of the skin frequently occurs in patients after allogeneic hematopoietic stem cell transplantation. Although T cell depletion reduces the incidence and severity, it does not completely prevent skin GVHD. This leads to a prolonged need for immunosuppressive medication in a significant number of patients. For the induction of acute GVHD, the stimulation of donor T cells by residing host antigen presenting cells such as Langerhans cells of the skin (LCs) plays a central role. The absence of donor T cells after depletion, however, seems to hamper an early switch of LCs from host to donor origin. Therefore, the monitoring of LC chimerism is of great interest. We and others have provided evidence for a delayed switch in LC chimerism after T cell depleted reduced intensity stem cell transplantation. However, the assays used so far either are imprecise when applying low numbers of isolated cells or they depend on the detection of the Y-chromosome in skin sections of sex-mismatched transplants. In an attempt to set up a more sensitive assay of general applicability, we combined the detection of donor chimerism and tissue specific markers in a single multiplex PCR. We established PCRs for 10 different cDNA regions of constitutively expressed genes containing single nucleotide polymorphisms (SNPs). The SNP-containing products of the multiplex PCR were subsequently analyzed by the primer extension method (minisequencing) and subsequently analyzed by capillary electrophoresis. All SNP-containing cDNAs were expressed in peripheral blood mononuclear cells (PBMCs) as well as in isolated CD4- and CD8-positive T-lymphocytes, in myeloid dendritic cells, LCs, and keratinocytes. When we tested this approach on PBMCs of 10 patients and their HLA-matched sibling donors, the assay distinguished all pairs in 1 to 6 out of 10 systems. In a subsequent step, the 10plex PCR was combined with the tissue specific markers langerin for LCs and cytokeratin 10 to distinguish LCs from keratinocytes. Their expression was detected using gene-specific probes in the same minisequencing reaction used for the detection of SNPS. The resulting 12plex assay distinguished sibling donors from the patients with the same specificity and, in the same reaction, detected Langerin as well as cytokeratin 10 in purified LCs and keratinocytes, respectively. In summary, we established a sensitive assay allowing the simultaneous detection of donor chimerism together with the tissue specificity of isolated LCs that is independent of sex-mismatched donors. The addition of further tissue specific markers might allow performing chimerism studies on other tissue resident antigen presenting cells.


Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 4581-4581
Author(s):  
Jieun Jang ◽  
Haerim Chung ◽  
Yu Ri Kim ◽  
Hoi-kyung Jeung ◽  
Ju-In Eom ◽  
...  

Abstract Background In the allogeneic hematopoietic stem cell transplantation, recent studies showed that T cell and natural killer (NK) cells recovery are implicated in the graft-versus-host disease (GVHD) and graft versus leukemia (GVL) effects. However, the significance of specific subsets of NK and T cell recovery in relation to transplantation outcomes remains to be elucidated in the haploidentical stem cell transplantation (haploSCT). Methods Clinical data of patients with acute myeloid leukemia (n = 21) and acute lymphoblastic leukemia (n = 24) who underwent their first haploSCT between September 2009 and December 2017 were analyzed. Peripheral blood mononuclear cells obtained from 27 patients were examined by multiparametric flow cytometric analysis. PD-1 and Tim-3 expression were examined in CD4+ and CD8+ T-cells and NK cell receptor (NKG2D, NKG2A, NKG2C, DNAM1 and NKp46) expression were analyzed in NK cells, respectively, at the 3 determined times (immediate prior to conditioning therapy, 28 and 90 days after haploSCT). Results Median age at haploSCT was 38 years (range, 21-62) and median follow-up duration was 31.6 months. Myeloablative conditioning was used for 32% and reduced intensity regimen for 68% of patients. GVHD prophylaxis was based on post-transplant cyclophosphamide for 8 (18%) or on anti-thymocyte-globulin for 36 (82%) plus standard prophylaxis. Incidence of grade II-IV acute GVHD was 50%, gastrointestinal tract (GIT) GVHD was 55.6%, non-GIT acute GVHD 35.7%, and chronic GVHD was 52.4%. Longitudinal analysis of immune reconstitution after haploSCT showed that the incidence of acute GVHD was associated with a delayed expansion of the NK cell population and incidence of chronic GVHD was associated with the extent of CD4+ T cell reconstitution. The incidence of acute GVHD was significantly higher in patients with lower counts of CD56bright CD16neg cell (100% for patients with less than 30 cells/uL at day 28 vs 50% for patients with higher counts, P = 0.026), particularly in NKG2A (P = 0.002) and DNAM1 (P = 0.027)-positive NK cell subsets. In univariate analysis, early CMV replication (P < 0.001), chronic GVHD (P = 0.001), donor age ≥ 28years (P = 0.018), CD4/CD8 ratio of product ≥ 2.4 (P = 0.033), and dose of infused T cells ≥ 3.91 x 108 /kg (P = 0.022) were significantly associated with lower 3-year cumulative incidence of relapse after haploSCT. Donor age ≥ 28years was significantly associated with high incidence of chronic GVHD (P = 0.002). Dose of infused T cells ≥ 3.91 x 108 /kg (HR, 0.088; CI, 0.009 to 0.823; P = 0.033) were independent factors for reducing leukemia relapse after adjustment in multivariate analysis. Chronic GVHD was an independent prognostic factor for higher leukemia-free survival rate (72.7% versus 20.1%, P = 0.008). Longitudinal analysis of T cell reconstitution after haploSCT showed that the high dose of infused T cells was associated with the increased expansion of CD4+PD-1- T cells (P = 0.031 at day 28 and P = 0.017 at day 90). Of note, The incidence of chronic GVHD was significantly higher in patients with higher counts of CD4+ T cell at day 28 (100% for patients with over than 150 cells/uL at day 28 vs 38.8% for patients with lower counts, P = 0.008), particularly in CD4+PD-1- subsets (P = 0.008). Among CD4+ T cell, PD-1-/PD-1+ ratio over than 4.5 was significantly associated with increased chronic GVHD (P = 0.005). In 22 patients with chronic GVHD, GIT GVHD was adverse prognostic factor for overall survival (59.5 % in GIT GHVD vs 100% in patients without GIT GVHD, P = 0.063). The incidence of GIT GVHD was significantly higher in patients with lower CD4/CD8 ratio at day 28 (77.8% for patients with less than 1.5 vs 0% for patients with higher ratio, P = 0.045). Conclusions Our findings suggest that high CD56brightCD16neg NK cell count at day 28 after hasploSCT was significantly associated with decreased incidence of acute GVHD. High dose of infused T cells was associated with increased reconstitution of CD4+ PD-1- T cells and high CD4+ T cell counts, particularly in PD-1- subset, are associated with increased development of chronic GVHD. These findings should be further validated for elucidating the roles of these immune effectors cells in the development of GVHD and GVL effect in haploSCT for acute leukemia. Disclosures Kim: Novartis Korea: Honoraria.


Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2976-2976
Author(s):  
Denis-Claude Roy ◽  
Sandra Cohen ◽  
Lambert Busque ◽  
Douglas Fish ◽  
Thomas Kiss ◽  
...  

Abstract Infection and disease relapse are the two major complications occurring after haplo-mismatched stem cell transplantation (SCT). Accelerating immune reconstitution would imply broader applicability of SCT by providing a transplant opportunity to the large number of patients who cannot find an HLA-matched related or unrelated donor. We have previously reported that photodynamic therapy (PDT) using TH9402 could selectively deplete donor alloreactive cell populations while preserving lymphocytes for immune responses. We present results of an ongoing Phase I clinical trial of haplo-mismatched allogeneic stem cell transplant (SCT) supplemented with DLIs PDT depleted of host-reactive T cells. Thirteen patients with high-risk hematologic malignancies (7 AML relapsed or refractory, 1 AML in CR3, 1 refractory ALL, 2 MDS, 1 NHL relapsing after autologous SCT, 1 refractory CLL) entered the trial. Eleven pts are evaluable for acute GVHD and reconstitution. Patients (7 M, 4 F) underwent transplantation with donor cells mismatched at 3 HLA Ags: 5 patients; 2Ags: 5 pts, and DR only: 1 pt). Donor mononuclear cells (MNCs) were incubated with recipient MNCs for 4 days, exposed to ATIR™ treatment (TH9402 PDT), stored frozen, and administered on day 33±6 after transplant at 5 graded DLI dose levels: 1×104 to 8×105 CD3+ cells/kg. Anti-host cytotoxic T lymphocyte precursors (CTLp) were depleted from DLIs by approximately 1.5 logs, and flow cytometry showed greater than 90% elimination of activated T cells (CD4+CD25+ and CD8+CD25+) by ATIR. All stem cell grafts underwent in vitro immunomagnetic T cell depletion using CD34+ positive cell selection. Median age at SCT was 56 years (range: 21–60). Eight patients were in partial remission or had progressive disease, and 3 patients were in complete remission at the time of SCT. Conditioning regimen consisted of TBI (1200 cGy), thiotepa (5 mg/kg) and fludarabine (40 mg/m2/day for 5 days) followed by infusion of CD3 depleted HSC grafts. No GVHD prophylaxis was administered. Evaluable patients showed durable hematologic engraftment: median time to >0.5×109 granulocytes/L was 11 days (8–20), and to >20×109 platelets/L without transfusion, 12 days (9–137) and all achieved complete donor chimerism. No patient developed acute GVHD (grade II–IV), while 3 patients developed signs of chronic GVHD. Four of the first 6 pts developed infectious complications in the first 6 months, and all resolved rapidly with appropriate therapy, except for EBV-PTLD in the first patient (1×104 CD3). Five patients died: 1 of relapsed CLL and 4 of infections (all after day+310), and all had received DLI containing 1.3 ×105 CD3+ cells (2 pts) or less. No other patient relapsed. The first 6 pts developed 10 infectious episodes (4 lethal), while none of the 5 pts receiving the highest DLI doses of CD3+ cells/kg developed any infection (median follow-up: 318 days). The overall disease-free-survival and survival are 57% at 1 year (median follow-up: 10.5 mo). Our results indicate that the post-transplant infusion of a ATIR-PDT treated DLI is feasible, does not induce acute GVHD, and suggests a clinical benefit for patients receiving the highest DLI doses to accelerate T cell reconstitution. This PDT strategy represents an appealing alternative for older patients and those at high risk for GVHD.


Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1118-1118
Author(s):  
Cavan Bailey ◽  
Michelle M Panis ◽  
Cihangir Buyukgoz ◽  
Tulin Budak-Alpdogan ◽  
Neal Flomenberg ◽  
...  

Abstract Donor lymphocyte infusion (DLI) has been successfully used clinically to augment the graft-versus-tumor (GVT) effect following hematopoietic stem cell transplantation (HSCT) in relapsed patients. However, improvements can still be made in enhancing anti-tumor activity, reducing graft-versus-host disease (GVHD) and decreasing complications from opportunistic infections. Our studies present clear evidence of increased tumor clearance via cytokine therapy in combination with DLI as a way to “boost” the infused cells function. Interleukin-15 (IL-15) is a potent cytokine that increases CD8+ T and NK cells number and function in normal mice and recipients of stem cell transplantation. Despite this, obstacles remain for use of IL-15 therapeutically, specifically its low potency and short in vivo half-life. To overcome this, a new IL-15 superagonist (IL-15 SA-(ALT-803)) has been developed with a longer half-life and increased potency. Administration of IL-15 SA to recipients of CFSE labeled T cells increases proliferation of CD8+T cells and IFN-γ and TNF-α secretion from CD8+T cells. We developed a murine DLI model by titrating the dose of infused T cells in a parent-F1 model, and then combined IL-15 SA administration with DLI in murine recipients of allogeneic HSCT. In this model, lethally irradiated CB6F1 (H2Kb/d) mice were transplanted with T- cell depleted bone marrow cells from C57BL6 mice (H2Kb). All recipients of HSCT were also co-injected A20 B-cell lymphoma cells transfected with a luciferase-producing gene, which allows bioluminescent imaging and tracking of tumor progress in vivo. Mice receiving DLI (2.5 X 105 T cells) with IL-15 SA injections given at 1μg/mouse on days 17 and 24 post-BMT show less tumor burden and increased overall survival (p = 0.04) and decreased tumor growth (p = 0.02) (Figure 1). The IL-15 SA treated group had a significantly less weight loss than the control group (p = 0.007). No GVHD symptoms were noted via weekly clinical scoring, highlighting both the efficacy and overall safety of the IL-15 SA therapy. Furthermore, we evaluated T- cell exhaustion markers on CD8+ T cells in surviving mice. We found increased programmed death-1 (PD-1) expression on T cells even when the tumor burden is cleared. Treatment with IL-15 SA reduced PD-1 expression on donor CD8+ T-cells in mice surviving more than 120 days post-transplant. We conclude that IL-15 SA enhances CD8+ T cell function by increasing cytokine secretion and proliferation of T cells whereas could also prevent T cell exhaustion. We suggest that IL-15 SA is a long-waited lymphoid growth factor and has the potential to use in combination with DLI for the treatment of recurrent disease after HSCT. Disclosures No relevant conflicts of interest to declare.


Hematology ◽  
2003 ◽  
Vol 2003 (1) ◽  
pp. 350-371 ◽  
Author(s):  
A. John Barrett ◽  
Katayoun Rezvani ◽  
Scott Solomon ◽  
Anne M. Dickinson ◽  
Xiao N. Wang ◽  
...  

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.


Sign in / Sign up

Export Citation Format

Share Document