scholarly journals Interleukin-12 Inhibits Graft-Versus-Host Disease Through an Fas-Mediated Mechanism Associated With Alterations in Donor T-Cell Activation and Expansion

Blood ◽  
1998 ◽  
Vol 91 (9) ◽  
pp. 3315-3322 ◽  
Author(s):  
Bimalangshu R. Dey ◽  
Yong-Guang Yang ◽  
Gregory L. Szot ◽  
Denise A. Pearson ◽  
Megan Sykes
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Graft Versus Host Disease ◽  
Acute Gvhd ◽  
Interleukin 12 ◽  
Cd4 Cells ◽  
Activation Markers ◽  
Host Disease ◽  
Graft Versus Host ◽  
Donor T Cells

We have recently made the paradoxical observation that a single injection of recombinant murine interleukin-12 (IL-12) on the day of bone marrow transplantation (BMT) inhibits graft-versus-host disease (GVHD) in lethally irradiated mice receiving fully major histocompatability complex (MHC)-mismatched bone marrow and spleen cells. We have now examined the mechanism of this effect of IL-12 on acute GVHD. By day 4 post-BMT, IL-12–treated mice showed marked reductions in splenic donor CD4+ and CD8+ T cells compared with GVHD controls. Expression of the early activation markers IL-2R alpha chain (CD25) and CD69 on splenic donor CD4+ cells was considerably higher at early time points (36 and 72 hours post-BMT) in IL-12–treated mice compared with GVHD controls. However, the later, GVHD-associated increase in CD25 and very late antigen-4 (VLA-4) expression on donor T cells was greatly depressed in IL-12–protected mice compared with GVHD controls. The marked GVHD-associated expansion of host-reactive T helper cells by day 4 was also completely inhibited in the IL-12–treated group. Expression of Fas was increased on donor CD4 cells of IL-12–treated mice compared with those of controls on days 3 through 7 post-BMT. Furthermore, the ability of IL-12 to protect against GVHD was at least partially dependent on the ability of donor cells to express functional Fas molecules. We conclude that IL-12 treatment at the time of BMT markedly perturbs the activation of alloreactive donor CD4+ T cells that play a critical role in the pathogenesis of acute GVHD. We hypothesize that these perturbations culminate in Fas-dependent apoptosis of donor T cells, thus impeding their expansion and their GVHD-promoting activity.

scholarly journals Interleukin-12 Inhibits Graft-Versus-Host Disease Through an Fas-Mediated Mechanism Associated With Alterations in Donor T-Cell Activation and Expansion

Blood ◽  
1998 ◽  
Vol 91 (9) ◽  
pp. 3315-3322 ◽  
Author(s):  
Bimalangshu R. Dey ◽  
Yong-Guang Yang ◽  
Gregory L. Szot ◽  
Denise A. Pearson ◽  
Megan Sykes
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Graft Versus Host Disease ◽  
Acute Gvhd ◽  
Interleukin 12 ◽  
Cd4 Cells ◽  
Activation Markers ◽  
Host Disease ◽  
Graft Versus Host ◽  
Donor T Cells

Abstract We have recently made the paradoxical observation that a single injection of recombinant murine interleukin-12 (IL-12) on the day of bone marrow transplantation (BMT) inhibits graft-versus-host disease (GVHD) in lethally irradiated mice receiving fully major histocompatability complex (MHC)-mismatched bone marrow and spleen cells. We have now examined the mechanism of this effect of IL-12 on acute GVHD. By day 4 post-BMT, IL-12–treated mice showed marked reductions in splenic donor CD4+ and CD8+ T cells compared with GVHD controls. Expression of the early activation markers IL-2R alpha chain (CD25) and CD69 on splenic donor CD4+ cells was considerably higher at early time points (36 and 72 hours post-BMT) in IL-12–treated mice compared with GVHD controls. However, the later, GVHD-associated increase in CD25 and very late antigen-4 (VLA-4) expression on donor T cells was greatly depressed in IL-12–protected mice compared with GVHD controls. The marked GVHD-associated expansion of host-reactive T helper cells by day 4 was also completely inhibited in the IL-12–treated group. Expression of Fas was increased on donor CD4 cells of IL-12–treated mice compared with those of controls on days 3 through 7 post-BMT. Furthermore, the ability of IL-12 to protect against GVHD was at least partially dependent on the ability of donor cells to express functional Fas molecules. We conclude that IL-12 treatment at the time of BMT markedly perturbs the activation of alloreactive donor CD4+ T cells that play a critical role in the pathogenesis of acute GVHD. We hypothesize that these perturbations culminate in Fas-dependent apoptosis of donor T cells, thus impeding their expansion and their GVHD-promoting activity.

The Role of Selective Depletion of Alloreactive Donor T Cells in Graft-Versus-Host Disease after Allogeneic Bone Marrow Transplantation.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 5167-5167
Author(s):  
Yihuan Chai ◽  
Huiying Qiu ◽  
Hui Lv
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Graft Versus Host Disease ◽  
Acute Gvhd ◽  
Allogeneic Bone Marrow ◽  
Third Party ◽  
Allogeneic Bone ◽  
Host Disease ◽  
Graft Versus Host ◽  
Donor T Cells

Abstract One of the main goals in allogeneic bone marrow(BM) transplantation is the abrogation of graft-versus-host disease (GVHD) with the preservation of antileukemia and antiviral activity. The Study present a selective T cell depletion strategy based on the physical separation of the alloreactive T cells, which were identified by expression of two activation-induced antigens (CD25 and CD69). T cells from C57BL/6(H-2b) mice were first activated with BALB/c (H-2d) recipient spleen cells in a 2-day mixed-lymphocyte-culture (MLC). Following this activation, this compound is selectively depleted based on expression of two activation-induced antigens CD25 and CD69 using magnetic cell sorting. The depleted cells or the untreated cells were then rechallenged respectively in a secondary MLC, with the same stimulator cells or a third-party (DBAH-2k) or tumor- specific (SP2/0, BALB/c-origin myeloma) cells. Cells proliferation were assayed at the indicated time points(1, 2, 3, 4, 5 days). These treated cells or control-cultured cells (2.0×106) mixed with 5.0×106 BM cells from C57BL/6 were transfused respectively by the trail vain into the lethally irradiated BALB/c to observe the survival time, GVHD incidence and pathological analysis. MLC assays demonstrated that this technique led to a significant decrease in alloreactivity of donor cells(29.02~64.17%), which at the same time preserved reactivity against third party cells(49.61~75.69%)and anti-tumor cells(61.14~68.62%). The mice in the group of control-coclutured were died of acute GVHD within 24days. The 7 recipient mice in the treated group were free of acute GVHD, and 3 mice were died of acute GVHD (aGVHD) within 23 days. MACS-based ex-vivo depletion of alloreactive donor T cells based on expression of two activation-induced antigens (CD25 and CD69) could inhibit anti-host responses, by contrast, anti-SP2/O and anti-third-party responses were preserved. Cotransplantation of these selected depleted cells and BM cells could reduce aGVHD.

Selective Depletion of Alloreacting CD25+ Cells from Stem Cell Allografts Can Reduce Acute Graft-Versus-Host Disease Following Matched Related Donor Transplantation.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 426-426
Author(s):  
Scott R. Solomon ◽  
Thao Tran ◽  
Charles S. Carter ◽  
Nancy Hensel ◽  
Laura Wisch ◽  
...  
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
Graft Versus Host Disease ◽  
Acute Gvhd ◽  
Cell Transplant ◽  
Host Disease ◽  
Graft Versus Host ◽  
Gvhd Prophylaxis ◽  
Donor T Cells ◽  
Related Donor

Abstract Graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality after allogeneic stem cell transplant (SCT), especially in older patients. We previously showed that host-reactive donor T cells are selectively depleted (SD) from an allograft ex vivo, following a short co-culture of donor cells with irradiated T cell stimulators from the recipient and subsequent treatment with an anti-CD25 immunotoxin. We report a pilot study to test the hypothesis that GVHD could be decreased in a cohort of elderly patients receiving SD allografts from HLA-identical sibling donors. Sixteen patients, median age 65 years (range 51–73), with advanced hematologic malignancies were transplanted following reduced-intensity conditioning with fludarabine and either cyclophosphamide (n=5), melphalan (n=5), or busulfan (n=6). Cyclosporine was used as the only additional GVHD prophylaxis. SD allografts contained a median CD34 dose of 4.5x106/kg (range 3.5–7.3) and an SD CD3 dose of 1.0x108/kg (range 0.2–1.5). Fifteen patients achieved sustained engraftment. The helper T lymphocyte precursor (HTLp) frequency assay demonstrated depletion of host-reactive donor T cells in 9/11 cases tested from a mean of 1/182,089 to 1/822,354 (mean 5.5-fold depletion), while third party responses were conserved. Kaplan-Meier estimates of probability of grade II-IV and grade III-IV acute GVHD were lower than those seen in a historical control group of patients receiving cyclosporine alone for GVHD prophylaxis (35±13% vs. 57±10%, p=0.34) and (7±6% vs. 38±6%, p=0.05), respectively. Of note, the two patients who developed visceral (gut ± liver) GVHD showed ineffective allodepletion by HTLp (figure). Chronic GVHD occurred in five of 14 evaluable patients. At a median follow-up of 212 days (range 60 – 690), seven of sixteen patients remain alive and in remission. Relapse deaths occurred in four patients (refractory AML [2], therapy-related MDS [1], and CMML [1]). Non-relapse mortality in this high-risk cohort of patients included graft failure [1], GVHD [2], infection [1], and myocardial infarction [1]. In summary, CD25-directed allodepletion of stem cell allografts can reduce clinically relevant acute GVHD following matched related donor transplantation. Figure Figure

scholarly journals Patient Bone Marrow Chimerism at Time of Donor Lymphocyte Infusion Predicts Development of Graft Versus Host Disease

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2132-2132
Author(s):  
Eva AS Koster ◽  
Liesbeth C. de Wreede ◽  
Sylwia Wallet-Malicka ◽  
Lisette Bogers ◽  
Peter van Balen ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
Graft Versus Host Disease ◽  
Hazard Ratio ◽  
The State ◽  
Host Disease ◽  
Graft Versus Host ◽  
Donor T Cells ◽  
Donor Type

Abstract After allogeneic stem cell transplantation (alloSCT), donor T cells targeting patient derived hematopoietic cells can induce a Graft versus Leukemia (GvL) effect preventing relapse. However, targeting of healthy patient tissues can cause Graft versus Host Disease (GvHD). The inflammatory environment induced by pre transplantation conditioning, the number of donor T cells in the graft, genetic disparity between patient and donor and the presentation of allo-antigens by activated patient derived antigen-presenting cells (APC) to donor T cells play a role in the development of GvL and/or GvHD. Donor T cell depletion (TCD) reduces GvHD and GvL. After TCD alloSCT, postponed prophylactic donor lymphocyte infusions (pDLI) are often needed to induce a GvL effect. When using 10/10 matched donors, our first dose of pDLI at six months after TCD alloSCT contained 3.0x10^6 T cells/kg (related donor, RD) or 1.5x10^6 T cells/kg (unrelated donor, UD). We evaluated whether the risk of developing GvHD after DLI is influenced by the donor type, intensity of the conditioning and/or patient bone marrow (BM) chimerism at time of DLI Sixty patients with acute leukemia (52 AML, 8 ALL; median age 57; 27 RD, 33 UD) received pDLI at a median of 6.4 months after TCD alloSCT in the absence of GVHD or relapse. Twenty-four patients received myeloablative (MA) conditioning consisting of cyclophosphamide and TBI. 36 patients received non-myeloablative (NMA) conditioning based on fludarabin and busulphan. TCD was performed by adding 20mg alemtuzumab to the graft. Only MA conditioned patients with an UD (n=12) received post transplantation ciclosporin as GvHD prophylaxis, which was tapered from 1 month after alloSCT. Clinically significant GvHD was defined as need of therapeutic systemic immunosuppression (tIS) for GvHD for at least 2 weeks or until death. Bone Marrow (BM) chimerism was measured prior to DLI. Three categories of patient chimerism levels were defined: no patient derived cells (absent), patient derived cells present, but < 5% (low), or ≥ 5% (high). In case of persisting or increasing patient chimerim after pDLI, a second DLI was given at 3-6 months after the first. A multi-state model was designed (Figure 1) with the first DLI (DLI1) as starting state and time. Patients starting tIS after DLI1 transit to the state tIS. Patients who need a second DLI, develop a relapse or die, transit to these respective states. Patients who stay in the state of DLI1 are considered to have a positive outcome. All patients had a follow-up of at least one year after DLI. Numbers in the boxes in Figure 1 represent the number of patients in that state at 1 year after DLI1 and numbers next to the arrows indicate the numbers of patients who made the transition between the two states. Donor type (unrelated versus related), conditioning (NMA versus MA) and patient BM chimerism at time of DLI were included in a Cox model for the transition hazards to investigate their association with the development of GvHD after DLI. For the total group, the cumulative incidence of tIS at 1 year after pDLI was 33% (95% CI 21-45%). Patients with an UD had a hazard ratio (HR) of 1.1 (95% CI 0.4-3.3) of needing tIS after DLI1 compared to patients with a RD. Compared to MA conditioning, NMA conditioned patients had a hazard ratio of 2.1 (95% CI 0.5-8.9) of needing tIS after DLI. They had a HR of 0.2 (95% CI 0.04-0.95) of stopping tIS compared to MA conditioned patients, indicating that DLI after NMA conditioning is associated with more severe GVHD. We hypothesized that this was due to the persistence of patient derived APC. BM chimerism at time of DLI was measured in 47 patients. After NMA and MA conditioning, BM patient chimerism was absent in 14% and 56%, low in 41% and 39%, and high in 45% and 6%, respectively (Fisher's exact test p=0.002 for difference between type of conditioning). Compared to the group without patient chimerism, the low and high patient chimerism group had a HR of 1.9 (95% CI 0.9-4.2) and 3.6 (95% CI 1.7-8.0) of needing tIS after DLI, respectively (Figure 2), demonstrating that the level of patient chimerism is a strong predictor for development of GvHD after DLI, even when taking into account the type of conditioning regimen. Patient BM chimerism at time of pDLI is a strong and independent predictor for the risk of developing GvHD. Dose reduction in case of an UD equalized the GvHD risk compared to a RD. When choosing a T cell dose for pDLI, patient chimerism should be considered a relevant parameter. Disclosures No relevant conflicts of interest to declare.

Protection Against Graft-Versus-Host Disease and Retention of Graft-Versus-Tumor Effect after Allogeneic BMT in Mice Conditioned with TLI and Anti-Thymocyte Serum.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3049-3049
Author(s):  
Asha Pillai ◽  
Pearline Teo ◽  
Samuel Strober
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Tumor Cells ◽  
Graft Versus Host Disease ◽  
Clinical Evidence ◽  
Acute Gvhd ◽  
Myeloablative Conditioning ◽  
Host Disease ◽  
Graft Versus Host ◽  
Graft Versus Tumor Effect

Abstract In a completely MHC-mismatched model of bone marrow transplantation [C57BL/6 (H-2b) donors into BALB/c (H-2d) hosts], we have developed a technique of non-myeloablative host conditioning using fractionated total lymphoid irradiation (TLI) and and anti-thymocyte serum (ATS) that prevents lethal graft-versus-host disease (GVHD). We have previously reported that this GVHD prevention is dependent on the secretion of IL-4 and on host regulatory NKT cells. In the current study, we assessed the graft-versus-tumor (GVT) effect of BMT to determine whether the GVT effect remains intact in this non-myeloablative conditioning model. Male BALB/c mice were given fractionated TLI (17 doses of 240 cGy each), 3 doses of ATS, and subsequently received intravenous infusion of 50 x 106 bone marrow and 60x 106 splenocytes from C57BL/6 donors, with and without the BCL1 B-cell lymphoma. Animals were observed for minimum of 100 days, and underwent autopsy at death to assess for sub-clinical evidence of GVHD or tumor infiltration. TLI/ATS-conditioned mice achieved a high percentage of donor chimerism, in the range of 50–100% in all lineages. TLI/ATS-conditioned hosts uniformly survived without signs of GVHD beyond day +100. By contrast, hosts conditioned with a single dose of 800cGy total body irradiation (TBI) died of acute GVHD (severe diarrhea, hunched back, weight loss) by day +21. When TBI/ATS or TBI-treated mice receive bone marrow, splenocytes, and BCL1 lymphoma, all hosts died with signs of acute GVHD by day +28. TLI/ATS-conditioned hosts receiving marrow, splenocytes and tumor cells showed no evidence of disease progression by day +100 and either cleared tumor idiotype completely or had persistence of low-intensity staining for tumor idiotype (tumor dormancy). TLI/ATS-conditioned hosts given BCL1 tumor cells without allogeneic BMT all succumbed to tumor. TLI/ATS hosts receiving bone marrow plus BCL1 without splenocytes all died by day +108 with high circulating BCL1 tumor burden and no clinical evidence of GVHD. The data indicate that peripheral donor T cells are necessary to maintain a robust graft-versus-tumor effect after TLI/ATS conditioning, and that complete donor chimerism is not a requirement for tumor eradication. In conclusion, using the TLI/ATS non-myeloablative conditioning regimen, it is possible to maintain a clinically significant graft-versus-tumor effect without inducing GVHD despite a high dose of infused donor peripheral T cells.

MiR-146a Regulates the TRAF6/TNF-Axis in Donor T Cells during Graft-Versus-Host Disease

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 843-843
Author(s):  
Natalie Stickel ◽  
Gabriele Prinz ◽  
Dietmar Pfeifer ◽  
Annette Schmitt-Graeff ◽  
Marie Follo ◽  
...  
Keyword(s):  
T Cells ◽  
Graft Versus Host Disease ◽  
Acute Gvhd ◽  
Negative Regulator ◽  
Snp Analysis ◽  
Hematopoietic Stem ◽  
Host Disease ◽  
Graft Versus Host ◽  
Donor T Cells

Abstract Introduction: Acute graft-versus-host disease (GvHD) arises from the attack of recipient tissues by donor allogeneic T cells and represents one of the major limitations of allogeneic hematopoietic cell transplantation (allo-HCT). In spite of many clinical trials, the standard immunosuppressive regimens for prevention of acute GvHD have improved little in the last two decades. Hence, a better understanding of the biology of acute GvHD may improve therapeutic options. MicroRNA-146a (miR-146a) was found to be increased in the sera of patients with GvHD. Therefore, we aimed to decipher the role of miR-146a in allogeneic donor T cells during GvHD by functional studies and in patients undergoing allo-HCT by single nucleotide polymorphism (SNP) analysis. Methods: We used two different murine major MHC mismatch models for acute GvHD. Recipient mice were conditioned with irradiation before transplantation of bone marrow and either wildtype or miR-146a deficient T cells from allogeneic donor mice. Furthermore, genomic DNA from 289 patients that underwent allo-HCT and their respective hematopoietic stem cell donors was isolated in order to determine their miR-146a rs2910164genotype. Results: We observed miR-146a upregulation in T cells of mice developing acute GvHD compared to untreated mice in a major MHC and a minor histocompatibility antigen mismatch model. Transfer of miR-146a deficient T cells caused increased GvHD severity, elevated TNF serum levels and reduced survival. Conversely, the phytochemical induction of miR-146a or its overexpression in donor T cells using a specific miR-146a mimic reduced GvHD severity. TNF receptor-associated factor 6 (TRAF6), a verified target of miR-146a, was upregulated in miR-146a-/- T cells following alloantigen stimulation. Higher TRAF6 levels translated into increased NF-κB activity and TNF production in miR-146a-/- T cells, while other pro-inflammatory cytokine levels were unaffected. The detrimental effect of miR-146a deficiency in T cells could be antagonized by TNF blockade in vivo. Moreover, in contrast to WT T cells, over expression of miR-146a in Tnf deficient T cells had no effect on their alloreactivity. In the human system, the minor genotype of the SNP rs2910164, which causes reduced miR-146a expression, was more frequent in patients developing acute GvHD grade III/IV compared to all other allo-HCT recipients (n=289). Conclusions: Taken together we show that miR-146a functions as a negative regulator of the TRAF6/TNF-axis in allogeneic donor T cells during GvHD, leading to reduced TNF transcription. Given our observation on the predictive role of the SNP leading to decreased miR-146a expression in acute GvHD in patients and the possibility to exogenously enhance miR-146a expression, we provide a novel and targeted molecular approach to mitigate GvHD. Disclosures No relevant conflicts of interest to declare.

scholarly journals Selective depletion of alloreactive donor lymphocytes: a novel method to reduce the severity of graft-versus-host disease in older patients undergoing matched sibling donor stem cell transplantation

Blood ◽  
2005 ◽  
Vol 106 (3) ◽  
pp. 1123-1129 ◽  
Author(s):  
Scott R. Solomon ◽  
Stephan Mielke ◽  
Bipin N. Savani ◽  
Aldemar Montero ◽  
Laura Wisch ◽  
...  
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
Graft Versus Host Disease ◽  
Older Patients ◽  
Acute Gvhd ◽  
Ex Vivo ◽  
Host Disease ◽  
Graft Versus Host ◽  
Cd34 Cells ◽  
Donor T Cells

AbstractWe have selectively depleted host-reactive donor T cells from peripheral blood stem cell (PBSC) transplant allografts ex vivo using an anti-CD25 immunotoxin. We report a clinical trial to decrease graft-versus-host disease (GVHD) in elderly patients receiving selectively depleted PBSC transplants from HLA-identical sibling donors. Sixteen patients (median age, 65 years [range, 51-73 years]), with advanced hematologic malignancies underwent transplantation following reduced-intensity conditioning with fludarabine and either cyclophosphamide (n = 5), melphalan (n = 5), or busulfan (n = 6). Cyclosporine was used as sole GVHD prophylaxis. The allograft contained a median of 4.5 × 106 CD34 cells/kg (range, 3.4-7.3 × 106 CD34 cells/kg) and 1.0 × 108/kg (range, 0.2-1.5 × 108/kg) selectively depleted T cells. Fifteen patients achieved sustained engraftment. The helper T-lymphocyte precursor (HTLp) frequency assay demonstrated successful (mean, 5-fold) depletion of host-reactive donor T cells, with conservation of third-party response in 9 of 11 cases tested. Actuarial rates of acute GVHD were 46% ± 13% for grades II to IV and 12% ± 8% for grades III to IV. These results suggest that allodepletion of donor cells ex vivo is clinically feasible in older patients and may reduce the rate of severe acute GVHD. Further studies with selectively depleted transplants to evaluate graft-versus-leukemia (GVL) and survival are warranted.

scholarly journals Interleukin-18 Regulates Acute Graft-Versus-Host Disease by Enhancing Fas-mediated Donor T Cell Apoptosis

2001 ◽  
Vol 194 (10) ◽  
pp. 1433-1440 ◽  
Author(s):  
Pavan Reddy ◽  
Takanori Teshima ◽  
Mark Kukuruga ◽  
Rainer Ordemann ◽  
Chen Liu ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Graft Versus Host Disease ◽  
Acute Gvhd ◽  
Host Disease ◽  
Murine Bone Marrow ◽  
Graft Versus Host ◽  
Donor T Cells ◽  
Ifn Γ ◽  
Acute Graft

Interleukin (IL)-18 is a recently discovered cytokine that modulates both T helper type 1 (Th1) and Th2 responses. IL-18 is elevated during acute graft-versus-host disease (GVHD). We investigated the role of IL-18 in this disorder using a well characterized murine bone marrow transplantation (BMT) model (B6 → B6D2F1). Surprisingly, blockade of IL-18 accelerated acute GVHD-related mortality. In contrast, administration of IL-18 reduced serum tumor necrosis factor (TNF)-α and lipopolysaccharide (LPS) levels, decreased intestinal histopathology, and resulted in significantly improved survival (75 vs. 15%, P &lt; 0.001). Administration of IL-18 attenuated early donor T cell expansion and was associated with increased Fas expression and greater apoptosis of donor T cells. The administration of IL-18 no longer protected BMT recipients from GVHD when Fas deficient (lpr) mice were used as donors. IL-18 also lost its ability to protect against acute GVHD when interferon (IFN)-γ knockout mice were used as donors. Together, these results demonstrate that IL-18 regulates acute GVHD by inducing enhanced Fas-mediated apoptosis of donor T cells early after BMT, and donor IFN-γ is critical for this protective effect.

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