Recipient tumor necrosis factor-alpha and interleukin-10 gene polymorphisms associate with early mortality and acute graft-versus-host disease severity in HLA-matched sibling bone marrow transplants

The proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) is strongly implicated in graft-versus-host disease (GVHD) and other acute bone marrow transplant (BMT) complications. The antiinflammatory interleukin-10 (IL-10) antagonizes TNF-alpha and reduces GVHD. We previously showed association of recipient TNF (TNFd) and IL-10 (IL-10(-1064)) gene polymorphisms with acute GVHD severity in matched sibling BMT using only cyclosporin A monotherapy. The current study tested association of GVHD with TNFd and IL-10(-1064/-1082) polymorphisms in a large cohort (144 matched sibling donor/recipient pairs) given both cyclosporine A (CyA) and methotrexate (MTX) prophylaxis. Genotype results were correlated with acute and chronic GVHD and mortality. Patients homozygous for the TNFd microsatellite allele 3 had higher early mortality: 23.7% of TNFd3/d3 homozygotes died before day 30, compared with 6.80% of non-d3/d3 recipients (P =.013). Recipients possessing longer IL-10(-1064) microsatellite alleles developed more severe acute GVHD: 22.3% of recipients possessing alleles 12 to 15 developed grade III to IV GVHD, versus 3.92% of those with smaller alleles (P <.01). Other recipient or donor genotypes tested did not significantly affect GVHD or mortality. We conclude that recipient TNFd and IL-10(-1064) polymorphisms associate with early mortality and severe acute GVHD in matched sibling BMT with dual prophylaxis. This supports the hypothesis of genetic predisposition towards GVHD and other BMT complications other than histocompatibility antigen disparity.     

Vitamin D receptor gene polymorphism associates with graft-versus-host disease and survival in HLA-matched sibling allogeneic bone marrow transplantation

We investigated the role of polymorphism of the vitamin D receptor (VDR) gene in HLA-matched sibling BMT for polymorphisms previously associated with human disease pathology. In intron 8 of the VDR gene, the B and A alleles of the BsmI and ApaI RFLPs were found to associate with reduced aGVHD when present in the patient's genotype. Logistic regression analysis demonstrated that patient VDR genotype, along with previously identified IL-10(-1064) and IFN-gamma genotype to be risk factors for severe acute GVHD. The A allele also associates with increased likelihood of death when present in the donor genotype (AA vs Aa or aa, hazard ratio 2.03, P = 0.0232). In patients who received increased prophylaxis with multi-agent therapy, patients whose graft was from a donor with an AA genotype had a substantially worse survival than patients whose graft was from a donor with a non-AA genotype (hazard ratio 12.93, P < 0.0001). Analysis of VDR genotype in prospective BMT recipients could indicate patients at risk of severe aGVHD. Analysis of VDR genotype in prospective BMT donors may identify individuals who have greater transplant-related mortality, and also allow appropriately restricted use of increased immunosuppressive prophylaxis.     

Increased intensity of acute graft-versus-host disease after reduced-intensity bone marrow transplantation compared to conventional transplantation from an HLA-matched sibling in children

Eight children underwent reduced-intensity stem cell transplantation (RIST) from an HLA-matched sibling. They received a fludarabine-melphalan based preparative regimen. Stem cell source was bone marrow, and GVHD prophylaxis consisted of cyclosporine A alone. Acute GVHD grade II-IV and grade III-IV were observed in four (50%) and three (37.5%), respectively, out of these eight patients. This incidence was significantly higher than that after conventional bone marrow transplantation, without severe tissue damage, in the same setting of stem cell source and GVHD prophylaxis. Although the number of patients is small, our results suggest that incidence of acute GVHD after RIST for children is significant. It should be remembered that RIST for children does not seem to be an easy transplant procedure from the viewpoint of acute GVHD, although RIST is less toxic.     

Chronic graft-versus-host disease in children and adolescents after bone marrow transplantation from HLA-matched donors

We analyzed 98 pediatric patients who underwent bone marrow transplantation (BMT) from serologically HLA-matched related donors (RD) or unrelated donors (UD) at our institute to clarify the actual status of chronic graft-versus-host disease (cGVHD). There were 36 evaluable cases of RD-BMT and 35 of UD-BMT. cGVHD was observed in 8 RD-BMT cases (22.2%) and in 23 UD-BMT cases (65.7%). In the RD-BMT cases, the limited and extensive types of cGVHD were observed in 4 cases each, whereas in the UD-BMT cases, the limited type was seen in 11 cases and the extensive type in 12. Prior acute GVHD was observed in 6 RD-BMT cases and in 18 UD-BMT cases. Two RD-BMT patients with extensive type cGVHD died of relapse and cytomegalovirus infection, and 4 UD-BMT patients died because of bronchiolitis obliterans, fungal infection, liver failure, and multiple organ failure, respectively. The incidence of cGVHD in these pediatric patients was as high as that in adult patients when UD-BMT was performed. Some UD-BMT patients required long-term immunosuppressive therapy after BMT. These findings suggest that cGVHD is a serious problem in pediatric UD-BMT. Therefore, intensive prophylaxis and treatment of GVHD must always be performed after UD-BMT.     

Risk factors for chronic graft-versus-host disease after HLA-identical sibling bone marrow transplantation

Chronic graft-versus-host disease (GVHD) is an important complication of bone marrow transplantation. We analyzed risk factors for chronic GVHD in 2,534 recipients of HLA-identical sibling transplants surviving at least 90 days after transplantation. The actuarial probability of developing chronic GVHD within three years posttransplant was 46% +/- 3% (95% confidence interval). The most important risk factor for chronic GVHD was acute GVHD. The 3-year probabilities of chronic GVHD were 28% +/- 3%, 49% +/- 5%, 59% +/- 6%, 80% +/- 9%, and 85% +/- 15% for persons with grades 0, I, II, III, and IV acute GVHD, respectively (P less than .0001). Among patients with no or grade I acute GVHD, recipient age greater than 20 years, use of non-T-cell depleted bone marrow, and alloimmune female donors for male recipients predicted a higher risk of chronic GVHD. When all three adverse risk factors were present, the probability of chronic GVHD was 62% among persons with no prior acute GVHD and 85% among those with grade I acute GVHD. Among patients with grade II through IV acute GVHD, no other risk factor predicted chronic GVHD. These data identify individuals who might benefit from treatment strategies aimed at changing the incidence of chronic GVHD.     

Phase I trial of interleukin-2 after unmodified HLA-matched sibling bone marrow transplantation for children with acute leukemia

Allogeneic bone marrow transplantation (BMT) for advanced acute leukemia is associated with a high risk of relapse. It is postulated that interleukin-2 (IL-2) administered after BMT might induce or amplify a graft-versus-leukemia effect and thereby reduce the relapse rate. To identify an IL-2 regimen for testing this hypothesis, a phase I trial of IL-2 (Roche) was performed in children in complete remission (CR) without active graft-versus-host disease (GVHD) off immunosuppressive agents after unmodified allogeneic matched-sibling BMT for acute leukemia beyond first remission. Beginning a median of 68 days after BMT, 17 patients received escalating doses of induction IL-2 (0.9, 3.0, or 6.0 x 10(6) IU/m2/d representing levels I, II, and III) for 5 days by continuous intravenous infusion (CIV). After 6 days of rest, they received maintenance IL-2 (0.9 x 10(6) IU/m2/d) for 10 days by CIV infusion. Levels I and II were well-tolerated, but, of 6 patients at level III, 1 developed pulmonary infiltrates, 1 developed hypotension (both resolved), and 1 died of bacterial sepsis and acute respiratory distress syndrome. Grade II acute GVHD developed in 1 patient at level I and 1 at level III. The maximum tolerated dose of induction IL-2 was level II. IL-2 induced lymphocytosis, with an increase in CD56+ and CD8+ cells. Ten patients remain in CR at 5+ to 67+ months. Thus, a regimen of IL-2 has been identified that did not induce a high incidence of acute GVHD when administered to children after unmodified allogeneic BMT. Its clinical activity will be assessed in a phase II trial.     

HLA-A3 increases and HLA-DR1 decreases the risk of acute graft-versus-host disease after HLA-matched sibling bone marrow transplantation for chronic myelogenous leukaemia

Bone disease in patients with thalassaemia major is a multifactorial and still poorly understood process. The present study evaluated 45 thalassaemic patients using dual X-ray absorptiometry at three sites (lumbar spine, head of femur and forearm) to assess bone mineral density, in parallel with a series of biochemical markers to measure bone formation and bone resorption. To identify possible interfering factors, our patients were grouped according to whether or not they needed transfusion therapy; the presence of hypogonadism was also considered. Our results showed that patients on regular transfusions had a markedly low bone mineral density in contrast to those not requiring blood support and that this finding was more pronounced in the hypogonadic group, irrespectively of sex. The decrease of bone mineral density values was more prominent in the forearm, thus making this site particularly interesting for such studies. Bone formation, as evidenced by the levels of serum alkaline phosphatase and osteocalcin, did not appear to be impaired, while bone resorption was grossly increased in all patient groups. The latter process was clearly evident using the recently introduced measurement of the urinary N-terminal peptides of collagen type I, the sensitivity of which has already been established in other groups of osteoporotic patients. Our conclusion is that, in spite of the severe bone destruction that occurs in thalassaemia major, the fact that bone formation remains intact calls for a more intensive treatment comprising hormonal replacement, bisphosphonates and other agents.     

Host defense and inflammatory gene polymorphisms are associated with outcomes after HLA-identical sibling bone marrow transplantation

We made the hypothesis that donor and recipient gene polymorphisms that drive the host response to microorganisms could be associated with infections after bone marrow transplantation (BMT). HLA-identical BMT was performed for patients with acute (n = 39) or chronic leukemia (n = 68). Genotyping was performed in 107 D/R DNA pairs for gene polymorphisms of cytokines (tumor necrosis factor-alpha [TNF-alpha] and TNF-beta, interleukin-1 receptor antagonist [IL-1Ra], IL-6, and IL-10), adhesion molecules (CD31 and CD54), Fcgammareceptors (FcgammaRIIa, IIIa, IIIb), mannose-binding lectin (MBL), and myeloperoxidase (MPO). First infection (overall) and first episodes of bacterial, viral, or invasive fungal infection were studied retrospectively for 180 days after BMT. Univariate and multivariate analyses, using death as a competing event, were performed to study risk factors. In multivariate analysis, first overall infections were increased in patients with the FcgammaRIIa R-131 genotype (hazard ratio [HR] = 1.92; P =.04), and severe bacterial infections were increased when the MPO donor genotype was AG or AA (HR = 2.16; P =.03). Viral and invasive fungal infections were not influenced by any genetic factor studied. Interestingly, we also found that (1) time to neutrophil recovery was shorter when donors were FcgammaRIIIb HNA-1a/HNA-1b (HR = 1.77; P =.002); (2) donor IL-1Ra (absence of IL-1RN*2) increased the risk for acute graft-versus-host disease (GVHD) (II-IV) (HR = 2.17; P =.017); and (3) recipient IL-10 (GG) and IL-1Ra genotypes increased the risk for chronic GVHD (P =.03 and P =.03, respectively). Finally, 180-day transplantation-related mortality rates were increased when donors were FcgammaRIIIb HNA-1a/HNA-1a or HNA-1b/HNA-1b (HR = 2.57; P =.05) and donor MPO genotype was AA (HR = 5.14; P =.004). In conclusion, donor and recipient gene polymorphisms are informative genetic risk factors for selecting donor/recipient pairs and could help in the understanding of mechanisms involved in host defenses of BM transplant recipients.     

HLA同胞全相合异基因造血干细胞移植后T细胞重建的规律

目的通过胸腺近输出功能和T细胞受体克隆谱型来研究同胞全相合骨髓移植后T细胞免疫重建。方法应用实时定量PCR的方法定量检测23例同胞全相合骨髓移植后不同时间及70例正常供者T细胞受体重排删除环（TRECs）水平;应用RT-PCR扩增其中10例患者骨髓移植后及5例正常供者外周血的T细胞受体β链可变区（TCRBV）24个家族的基因序列,通过基因扫描的方法判断TCRBV家族的克隆表达、互补决定区3（CDR3）克隆性质及计算TCRBV家族的利用率。结果70例正常人外周血单个核细胞中TRECs为（3351．1±3711．1）拷贝／10^5细胞,年龄与TRECs含量呈负相关。移植前患者TRECs定量检测结果为（307．9±433．3）拷贝／10^5细胞,明显低于正常人。移植后1～5个月患者TRECs水平均明显下降,部分患者未能检测到TRECs。移植后6个月TRECs明显升高并持续1年;移植后24个月TRECs水平有较大提高并接近移植前状态。移植后2～15个月,10例患者在7～16个BV家族有表达,且多克隆表达率为48％,单克隆及寡克隆分布在24个BV家族。结论在移植后早期TRECs为低水平并持续一段时间。移植后6个月,胸腺产生一定数量的初始T细胞并且TCRBV CDR3谱型显示BV家族的利用及多克隆的表达均在增加。     

Donor alloreactivity may predict acute graft-versus-host disease in HLA-matched bone marrow transplantation for leukemia in early remission.

The pretransplant alloantigen-dependent responding and stimulating capacity of donors and of recipients was studied retrospectively, in a study of prediction of acute graft-versus-host disease. Donor responding capacity (DRC) and host stimulating capacity (HSC) were defined by mixed lymphocyte culture (MLC) and normalized by help of the pool response. High and low DRC and strong and weak HSC was defined by distribution plots. Kaplan-Meier estimates of the risk of developing Grade II or higher aGvHD showed that first remission patients (N = 125) had a significantly different risk if transplanted with marrow from a donor with high (N = 54) or low (N = 71) DRC (chi 2 = 9.49; d.f. = 1; p less than 0.002). This was not the case for patients transplanted in later remissions. Host SC status had no significant influence on the aGvHD status (chi 2 = 1.75 and 2.40; d.f. = 1; p = 0.19 and 0.12, defined by normal controls A and B respectively). In conclusion, the results indicate that pretransplant donor alloreactivity may predict aGvHD, confirming the results from a Scandinavian study. The results need to be confirmed in prospective studies of alloreactivity as risk factor for aGvHD.     

Polymorphisms of transforming growth factor-beta1 and transforming growth factor-beta1 type II receptor genes are associated with acute graft-versus-host disease in children with HLA-matched sibling bone marrow transplantation

The aim of this study was to determine whether the gene polymorphisms of Th1/Th2 and immunoregulatory cytokines were associated with aGVHD in Japanese children receiving allogeneic bone marrow transplantation (allo BMT). We investigated polymorphisms of genes encoding interleukin (IL)-4, IL-4 receptor (IL-4 R), IL-10, transforming growth factor (TGF)-beta1, TGF-beta1 type II receptor (TGF-beta1 RII), interferon (IFN)-gamma, IFN-gamma type 2 receptor (IFN-gamma R2), and IFN regulatory factor (IRF)-1. Sixty-seven patients were treated with allo BMT from HLA-identical siblings, and aGVHD was observed in 38. TGF-beta1 codon 10 leucine (Leu) /proline (Pro) polymorphism in donors was associated with the development of aGVHD. Patients having donors with the Pro allele had aGVHD more frequently than those without Pro allele (30/45 vs 8/20, odds ratio = 3.00; P = 0.04). TGF-beta1 RII 1167 C/T polymorphism in recipients was also associated with the development of aGVHD. The incidence was significantly higher in recipients with T allele than in those without T allele (21/27 vs 16/35, odds ratio = 4.16; P = 0.01). In conclusion, genetic backgrounds of TGF-beta1 and TGF-beta1 RII may be involved in the development of aGVHD in HLA-matched sibling BMT in Japanese children.     

Predicting the severity of graft-versus-host disease from interleukin-10 levels after bone marrow transplantation

Acute graft-versus-host disease (GVHD) is the most important complication of allogeneic bone marrow transplantation. We investigated the possibility of predicting severe acute GVHD using plasma interleukin-10 levels in 31 patients who underwent allogeneic bone marrow transplantation. In patients with acute GVHD, the interleukin-10 (IL-10) level increased significantly from the aplastic phase through the leukocyte recovery phase after transplantation (P < 0.05, paired t-test). The ratio of the IL-10 level in the aplastic phase to that in the leukocyte recovery phase was significantly correlated with the severity of acute GVHD (P < 0. 05, t-test), and the incidence of grade III or IV disease was significantly increased (P < 0.0001). Since IL-10 antagonizes various other cytokines that induce acute GVHD, determination of the IL-10 level is equivalent to assessing the total production of cytokines promoting GVHD. The ratio of the IL-10 level in the aplastic phase to that in the recovery phase seems to be useful for predicting the subsequent risk of acute GVHD.     

Orthotopic liver transplantation for graft-versus-host disease following bone marrow transplantation

Chronic graft-vs.-host disease occurs in 30%-50% of long-term survivors of allogeneic bone marrow grafts, and may eventuate in cirrhosis. In this study, a young woman, originally diagnosed as having acute myelogenous leukemia, underwent successful bone marrow transplantation but later developed graft-vs.-host disease-induced cirrhosis and recurrent variceal hemorrhage. She underwent successful orthotopic liver transplant. Her postoperative course was uncomplicated, with no evidence of rejection or recurrence of graft-vs.-host disease. As bone marrow transplantation is more widely used and survival improves, the number of patients with graft-vs.-host disease or venoocclusive disease resulting in cirrhosis is likely to increase. Hepatic transplantation should be considered for bone marrow transplant patients who develop end-stage liver disease.     

Interferon-gamma and interleukin-10 gene polymorphisms in pulmonary tuberculosis

Several genes coding for different cytokines may affect host susceptibility to tuberculosis. This study investigates the relationship of the single base change polymorphic variants identified in the first intron of interferon-gamma (+874 T/A) and in the promoter region of interleukin-10 gene (-1,082 G/A), with cytokine production by peripheral blood mononuclear cells and tuberculosis susceptibility. We studied a Spanish population of 113 patients with culture-proven pulmonary tuberculosis, 207 healthy close contacts (125 tuberculin reactive and 82 tuberculin negative), and 100 healthy tuberculin-negative control subjects. Multiple logistic regression analysis showed that individuals homozygous for the interferon-gamma (+874) A allele had a 3.75-fold increased risk of developing tuberculosis (95% confidence interval, 2.26-6.23, p = 0.0017). Stimulated production of interferon-gamma by peripheral mononuclear cells from patients with genotype AA was depressed compared with that of non-AA homozygotes at the time of diagnosis and after completion of therapy. Multivariate analysis showed that the presence of an AA genotype and the absolute number of lymphocytes were the only independent predictors of interferon-gamma production. In contrast, the different rates of interleukin-10 production associated with the interleukin-10 polymorphism did not affect susceptibility to tuberculosis. Thus, a genetic defect in the production of interferon-gamma in individuals homozygous for the (+874) A allele could contribute to their increased risk of developing tuberculosis.     

Transfusions shortly before HLA-matched marrow transplantation for leukemia are associated with a decrease in chronic graft-versus-host disease

The effect of random red cell transfusions given shortly before allogeneic bone marrow transplantation (BMT) was evaluated in 969 leukemic patients transplanted from an HLA-identical sibling donor. Patients were divided into two groups: 501 who received a transfusion shortly before BMT, and 468 who did not. Both groups had a similar incidence of acute graft-versus-host disease (GVHD), but the recently-transfused group had a significantly lower incidence of chronic GVHD (35.9% vs 48.9%). These differences remained significant in a multivariate analysis of time to chronic GVHD (p = 0.022), taking into account other differences between the two groups and known risk factors for chronic GVHD.     

Quantitative assessment of posttransplant host-specific interleukin-2- secreting T-helper cell precursors in patients with and without acute graft-versus-host disease after allogeneic HLA-identical sibling bone marrow transplantation

Recent studies in mice and humans have emphasized an important contribution of host-reactive minor histocompatibility antigen (mH)- specific lymphokine-secreting donor T-helper cells (Th) for the induction of acute graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation (BMT). By using limiting dilution (LD) and clonal specificity analyses, we investigated in 14 patients with and without acute GVHD after non-T-depleted HLA-identical sibling BMT whether posttransplant host-reactive mH-specific interleukin-2 (IL-2)- secreting Th are involved in the development of clinically significant acute GVHD and the establishment of tolerance. At different time intervals posttransplant (I, days 0 through 45; II, days 45 through 90; III, days 90 through 180), host-specific IL-2-secreting Th-precursors (Th-p) were quantitatively assessed in six patients during clinically apparent grade II-III acute GVHD. Frequencies of responding Th-p ranged from 1/13,000 to 1 4,000. The presence of host-specific Th-p was significantly correlated with the development of grade II-III acute GVHD (P = .0003 by Fisher's exact test). The detectability of host- specific Th-p preceded the clinical onset of grade II-III acute GVHD. Host-specific Th-p were no longer detectable after the clinical resolution of grade II-III acute GVHD. No subsequent chronic GVHD was observed in these patients. However, prolonged occurrence of host- specific Th-p was accompanied by clinically persisting acute GVHD and the onset of secondary chronic GVHD. In patients with no acute GVHD (grade 0) (n = 7) and grade I (n = 1) acute GVHD, host-specific Th-p were not detectable at all. We conclude that host-reactive Th are critically involved in the development and maintenance of acute GVHD and may contribute to the establishment of tolerance after genotypically HLA-identical sibling BMT.     

Administration of interleukin-7 after allogeneic bone marrow transplantation improves immune reconstitution without aggravating graft-versus-host disease

Prolonged immunodeficiency after allogeneic bone marrow transplantation (BMT) causes significant morbidity and mortality from infection. This study examined in murine models the effects of interleukin-7 (IL-7) given to young and middle-aged (9-month-old) recipients of major histocompatibility complex (MHC)-matched or -mismatched allogeneic BMT. Although administration of IL-7 from day 0 to 14 after syngeneic BMT promoted lymphoid reconstitution, this regimen was ineffective after allogeneic BMT. However, IL-7 administration from day 14 (or 21) to 27 after allogeneic BMT accelerated restoration of the major lymphoid cell populations even in middle-aged recipients. This regimen significantly expanded donor-derived thymocytes and peripheral T cells, B-lineage cells in bone marrow and spleen, splenic natural killer (NK) cells, NK T cells, and monocytes and macrophages. Interestingly, although recipients treated with IL-7 had significant increases in CD4(+) and CD8(+) memory T-cell populations, increases in naive T cells were less profound. Most notable, however, were the observations that IL-7 treatment did not exacerbate graft-versus-host disease (GVHD) in recipients of an MHC-matched BMT, and would ameliorate GVHD in recipients of a MHC-mismatched BMT. Nonetheless, graft-versus-leukemia (GVL) activity (measured against 32Dp210 leukemia) remained intact. Although activated and memory CD4(+) and CD8(+) T cells normally express high levels of IL-7 receptor (IL-7R, CD127), activated and memory alloreactive donor-derived T cells from recipients of allogeneic BMT expressed little IL-7R. This might explain the failure of IL-7 administration to exacerbate GVHD. In conclusion, posttransplant IL-7 administration to recipients of an allogeneic BMT enhances lymphoid reconstitution without aggravating GVHD while preserving GVL.     

FK506 (Tacrolimus) monotherapy for prevention of graft-versus-host disease after histocompatible sibling allogenic bone marrow transplantation

FK506 (Tacrolimus) is an immunosuppressive drug that blocks the activation of antigen-specific T lymphocytes, a major component in the pathogenesis of graft-versus-host disease (GVHD). This study was designed to obtain first estimates of the safety and efficacy of FK506 monotherapy in the prevention of GVHD following HLA-identical sibling marrow transplantation. Additionally, a subset of patients was studied to define the pharmacokinetic profile of FK506. Twenty-seven adult patients with leukemia or myelodysplasia received FK506 starting the day before transplant at a dose of 0.04 mg/kg/d by continuous intravenous infusion. When clinically possible, FK506 was given orally in two divided doses starting at five times the daily intravenous dose. FK506 doses were adjusted to target a steady state or trough blood level between 10 to 30 ng/mL. These patients were followed for 6 months posttransplant. All patients had sustained marrow engraftment. Frequently noted adverse events included reversible renal dysfunction, diarrhea, fever, nausea, vomiting, and headache. Most patients required FK506 dose reductions associated with elevated serum creatinine. Two (7%) patients relapsed, one of whom died of the disease within the 6- month study period. A second patient died due to pulmonary mucor. Whole blood pharmacokinetic parameters indicated a half-life of 18.2 +/- 12.1 hours; volume of distribution of 1.67 +/- 1.02 L/kg; clearance of 71 +/- 34 mL/h/kg; and bioavailability of 32 +/- 24%. Eleven of 27 (41%) patients developed grade II to IV acute GVHD, including 10 grade II and one grade III. Six of 24 (25%) evaluable patients developed chronic GVHD. These data indicate that FK506 monotherapy has activity in preventing GVHD. Further studies of FK506 with lower doses to improve tolerability and in combination with other immunosuppressants to augment efficacy are warranted.