Late graft rejection and second infusion of bone marrow in children with aplastic anaemia

Late graft rejection following allogeneic bone marrow transplantation (BMT) for aplastic anaemia is a significant clinical problem and is associated with a high risk of mortality. We report two children with severe aplastic anaemia (SAA) who developed very late graft rejection 2 years and 4 months and 10 years respectively after allogeneic BMT from HLA-identical siblings. Following a second BMT from their initial donors, engraftment has been sustained in both cases. The patients are alive with full donor chimaerism, 18 and 19 years from initial transplant. These cases illustrate that graft failure can be an extremely late event after allogeneic BMT for SAA, and that long-term sustained engraftment can be achieved in these patients with second BMT from the original donors.     

Cyclophosphamide/antithymocyte globulin conditioning of patients with severe aplastic anemia for marrow transplantation from HLA-matched siblings: Preliminary results

Many approaches have been taken to reducing the rate of graft failure and the incidence of graft-versus-host disease (GVHD) in bone marrow transplantation (BMT) of patients with severe aplastic anemia (SAA). The combination of cyclophosphamide with irradiation has had unequivocal success in reconstituting a sustained engraftment, but this procedure has severe associated risks such as second malignancies. Recently, cyclophosphamide (CYC) plus antithymocyte globulin (ATG) has been shown to be an effective alternative to irradiation-based programs in retransplants. Based on these experiences, the current clinical trial was started to prepare patients suffering from SAA for marrow transplantation from HLA-identical siblings with ATG plus CYC. Nine patients have been enrolled into the study so far. They received a total dose of 200 mg/kg CYC and concomitantly 120 mg/kg or 90 mg/kg ATG, followed by cyclosporine plus methotrexate as post-transplantation GVHD prophylaxis. Eight of nine patients survived without any transplant-associated complications; i.e., they had a documented stable engraftment without rejection and without acute or chronic GVHD. One patient died due to anAsper-gillus sepsis prior to a definite engraftment. Although our data are preliminary because of the small number of patients enrolled and a follow-up of only 30 months, CYC plus ATG appears to be an effective preparative regimen for BMT in patients with SAA, resulting in a favorable outcome.     

Complete remission in severe aplastic anemia after high-dose cyclophosphamide without bone marrow transplantation

Severe aplastic anemia (SAA) can be successfully treated with allogeneic bone marrow transplantation (BMT) or immunosuppressive therapy. However, the majority of patients with SAA are not eligible for BMT because they lack an HLA-identical sibling. Conventional immunosuppressive therapy also has major limitations; many of its remissions are incomplete and relapse or secondary clonal disease is common. Cyclophosphamide is a potent immunosuppressive agent that is used in all BMT conditioning regimens for patients with SAA. Preliminary evidence suggested that high-dose cyclophosphamide, even without BMT, may be beneficial to patients with SAA. Therefore, 10 patients with SAA and lacking an HLA-identical sibling were treated with high-dose cyclophosphamide (45 mg/kg/d) for 4 consecutive days with or without cyclosporine. A complete response (hemoglobin level, > 13 g/dL; absolute neutrophil count, > 1.5 x 10(9)/L, and platelet count > 125 x 10(9)/L) was achieved in 7 of the 10 patients. One of the complete responders died from the acquired immunodeficiency syndrome 44 months after treatment with high-dose cyclophosphamide. The 6 remaining patients are alive and in continuous complete remission, with a median follow-up of 10.8 years (range, 7.3 to 17.8 years). The median time to last platelet transfusion and time to 0.5 x 10(9) neutrophils/L were 85 and 95 days, respectively. None of the complete responders has relapsed or developed a clonal disease. These results suggest that high-dose cyclophosphamide, even without BMT, may be more effective than conventional immunosuppressive therapy in restoring normal hematopoiesis and preventing relapse or secondary clonal disorders. Hence, further studies confirming the efficacy of this approach in SAA are indicated.     

Allogeneic bone marrow transplantation with T-cell-depleted marrow grafts for patients with poor-risk relapsed low-grade non-Hodgkin's lymphoma

We present the clinical results of allogeneic bone marrow transplantation (BMT) with T-cell-depleted grafts from HLA-matched sibling donors in patients with poor-risk relapsed low-grade non-Hodgkin's lymphoma (NHL). Poor risk was defined as relapse within 12 months after or progression during prior treatment. The conditioning regimen consisted of cyclophosphamide and total-body irradiation with or without additional idarubicin. Donor marrow was depleted of T lymphocytes using counterflow centrifugation. Post-BMT prophylaxis of graft-versus-host disease (GvHD) consisted of cyclosporine A. 15 patients with a median age of 47 years (range 30–57) were transplanted. All patients engrafted. After a median follow-up of 36 months (range 9–78), 10 patients were alive and in complete remission (CR). Two of them had relapsed after BMT but re-entered CR following infusions of leucocytes from the original bone marrow donor. Five patients died; causes of death were cardiomyopathy ( n  = 1), chronic GvHD ( n  = 1) and infection during chronic GvHD ( n  = 3). We conclude that allogeneic T-cell-depleted bone marrow transplantation is an efficacious treatment for patients with poor-risk relapsed low-grade NHL. Infusions of donor leucocytes reinduced CR in the two patients with relapse after BMT.     

High-dose peripheral blood stem cell transplant for multitransfused severe aplastic anaemia patients without antithymocyte globulin in the conditioning regimen.

Four multitransfused patients with severe aplastic anaemia (SAA) are described. Two received a BMT after conditioning with cyclophosphamide (Cy) plus antithymocyte globulin (ATG). Both suffered a graft failure (GF) and had a second transplant with PBSC from the original donor. Two other patients received a PBSCT as a first option, with Cy as the only conditioning drug. The four patients received methotrexate (MTX) and cyclosporine (CYA) as post-grafting immunosuppression. The two BMT patients with GF were successfully rescued with a PBSC second transplant. In the two cases where a PBSCT was done as a first option no GF was observed and a successful and complete haematological recovery was achieved. In conclusion, PBSCT rescued two SAA patients with GF after BMT. PBSCT without ATG as a first option produced a quick and complete haematological recovery in two additional patients, suggesting that PBSCT without ATG can be an alternative to BMT plus ATG in SAA as a first transplant option.     

Bone marrow transplantation for patients with acquired severe aplastic anemia using cyclophosphamide and antithymocyte globulin: the experience from a single center

Between 1998 and 2001, 31 (24 male, 7 female) patients with severe aplastic anemia (SAA) and a median age of 19 years (range, 4-39 years) received an allogeneic bone marrow transplantation. Marrow donors were genotypically HLA-identical siblings in 30 cases and a monozygous twin in one case. The median time from diagnosis to bone marrow transplantation was 1 month (range, 0.5-5 months). Conditioning regimen consisted of cyclophosphamide (CY) combined with antithymocyte globulin (ATG), in all patients. For graft-versus-host disease (GvHD) prophylaxis, all patients received methotrexate and cyclosporin. A total of 84% of patients had sustained grafts, whereas 16% rejected grafts between 3 and 20 months after transplantation. Of the five rejecting patients, three are alive with successful second engraftments and two died from infections. Acute grade II-IV GvHD was seen in only 11% of patients. A limited chronic GvHD was seen in one patient. With a median follow-up of 18 months (range, 5-42 months), survival rate was 86% and Karnofsky score was at least 90%. This study confirms the high success rate of the CY/ATG regimen in SAA allografted from an HLA-identical sibling. Early and late graft failure remains a problem and may require modification of this regimen.     

Non-total body irradiation containing preparative regimen in alternative donor bone marrow transplantation for severe aplastic anemia

Using non-total body irradiation (TBI) containing preparative regimens, 13 patients with severe aplastic anemia (SAA) were transplanted from an alternative donor in a single institute. In total, 12 donors were unrelated volunteers and one was an HLA one-locus mismatched sibling. Median time from diagnosis of SAA to bone marrow transplantation (BMT) was 10.1 months (range, 1.6-180.1). Nine patients had received immunosuppressive treatment with ATG before BMT, while four had not. Preparative regimens consisted of cyclophosphamide plus ATG in nine patients, cyclophosphamide plus fludarabine in two patients, and cyclophosphamide plus fludarabine plus ATG in two patients. All patients received non-T-cell depleted bone marrow from the donor. Cyclosporine plus methotrexate were given for GVHD prophylaxis. All patients engrafted on a median of day 21 (range, 15-27). Grade III-IV acute GVHD developed in three (23%) of 13 patients and extensive chronic GVHD in four (31%) of 12 evaluable patients. With a median follow-up duration of 1138 days (range, 118-1553), 10 patients are alive with durable engraftment showing 74.6% (95% confidence interval, 49.5-99.7%) of survival rate. Cause of the deaths was CNS bleeding in one and chronic GVHD in two. In conclusion, non-TBI containing preparative regimen could ensure durable engraftment in alternative donor BMT for SAA and showed promising results.     

Role of allogeneic bone marrow transplantation from an HLA-identical sibling or a matched unrelated donor in the treatment of children with juvenile chronic myeloid leukaemia

Seven children (age range 1.8–11 years) with juvenile chronic myelomonocytic leukaemia (JCML) received an allogeneic bone marrow transplantation (BMT), four from an HLA-identical sibling and three from a matched unrelated donor. In the four children transplanted using an HLA-identical sibling, conditioning regimen included busulfan (BU), cyclophosphamide (CY) and melphalan (L-PAM), whereas graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine-A (Cs-A). The preparative regimen was well tolerated and all patients engrafted promptly. None of the patients have relapsed and all four children remain in haematological remission after an observation time of 7, 24, 25 and 48 months, respectively. Of the three children given BMT from an unrelated volunteer, one was <2 years of age and she received the BU/CY/L-PAM regimen. In view of the increased risk of graft rejection described in patients transplanted from unrelated donors, we chose to prepare the other two patients with fractionated total body irradiation (TBI), thiotepa and CY. Cs-A, short-term methotrexate and Campath-1G in vivo were employed to prevent GVHD in this group of patients. Graft failure with autologous reconstitution of haemopoiesis occurred in the child given the chemotherapy-based regimen. One of the two girls given TBI relapsed after BMT; therefore only one of the three patients who received a marrow transplant from a matched unrelated donor survives in complete haematological remission 10 months after BMT. Our study suggests that the conditioning regimen we employed for allogeneic BMT from a compatible sibling is an effective means of eradicating the leukaemic clone. In our experience, results obtained using unrelated donors are less satisfactory and, at present, the use of such donors seems to be riskier and associated with a lower success rate as compared with BMT from an HLA-identical sibling.     

Role of allogeneic bone marrow transplantation from an HLA-identical sibling or a matched unrelated donor in the treatment of children with juvenile chronic myeloid leukaemia

Seven children (age range 1.8–11 years) with juvenile chronic myelomonocytic leukaemia (JCML) received an allogeneic bone marrow transplantation (BMT), four from an HLA-identical sibling and three from a matched unrelated donor. In the four children transplanted using an HLA-identical sibling, conditioning regimen included busulfan (BU), cyclophosphamide (CY) and melphalan (L-PAM), whereas graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine-A (Cs-A). The preparative regimen was well tolerated and all patients engrafted promptly. None of the patients have relapsed and all four children remain in haematological remission after an observation time of 7, 24, 25 and 48 months, respectively. Of the three children given BMT from an unrelated volunteer, one was <2 years of age and she received the BU/CY/L-PAM regimen. In view of the increased risk of graft rejection described in patients transplanted from unrelated donors, we chose to prepare the other two patients with fractionated total body irradiation (TBI), thiotepa and CY. Cs-A, short-term methotrexate and Campath-1G in vivo were employed to prevent GVHD in this group of patients. Graft failure with autologous reconstitution of haemopoiesis occurred in the child given the chemotherapy-based regimen. One of the two girls given TBI relapsed after BMT; therefore only one of the three patients who received a marrow transplant from a matched unrelated donor survives in complete haematological remission 10 months after BMT. Our study suggests that the conditioning regimen we employed for allogeneic BMT from a compatible sibling is an effective means of eradicating the leukaemic clone. In our experience, results obtained using unrelated donors are less satisfactory and, at present, the use of such donors seems to be riskier and associated with a lower success rate as compared with BMT from an HLA-identical sibling.     

Cyclophosphamide and other new agents for the treatment of severe aplastic anemia

Severe aplastic anemia (SAA) has a poor prognosis in the absence of treatment. Current accepted therapeutic strategies include allogeneic stem-cell transplantation and immunosuppression, both resulting in long-term survival in the majority of patients. Although human leukocyte antigen (HLA)-matched sibling stem-cell transplantation is highly effective, the 25% probability of finding a suitable sibling donor within a family renders this approach available to only a minority of patients. Transplantation using HLA-matched, unrelated donors carries a high risk of treatment failure along with considerable toxicity. While combined immunosuppression with both antithymocyte globulin (ATG) and cyclosporine A (CSA) produces hematologic improvement in most patients, relapse is common. Late evolution of aplastic anemia to other serious hematologic disorders, including paroxysmal nocturnal hemoglobinuria (PNH), myelodysplasia, and acute leukemia, is also a significant problem following treatment with ATG/CSA. Recently, results of immunosuppression in SAA with another potent immunosuppressive agent, cyclophosphamide, were reported in a small number of patients. The overall response rate was similar to that seen with ATG/CSA, but relapse and late clonal disease were not observed during a long period of follow-up. A larger randomized trial comparing sustained hematologic response rates to either conventional immunosuppression with ATG/CSA or high-dose cyclophosphamide and CSA is now underway; secondary end points include response duration, event-free survival, and overall survival. Additionally, a number of protocols designed to test the efficacy of alternative immunosuppressive or immunomodulatory agents are being developed.     

HLA配型相合的造血干细胞移植治疗重型再生障碍性贫血的临床研究

目的 评价HLA配型相合的异基因造血干细胞移植(allo-HSCT)治疗重型再生障碍性贫血(SAA)的疗效.方法 2000年1月至2008年11月采用allo-HSCT治疗SAA患者20例,其中同胞相合移植17例,非血缘关系移植3例.预处理采用环磷酰胺(Cy)50 mg·kg~(-1)·d~(-1)4 d加抗淋巴细胞免疫球蛋白(ATG)2.5 mg·kg~(-1)·d~(-1)或20 mg·kg~(-1)·d~(-1) d.移植物抗宿主病(GVHD)的预防方案为经典的环孢素A(CsA)联合短程甲氨蝶呤(MTX)及霉酚酸酯(MMF).同胞供者采集经重组人粒细胞集落刺激因子(G-CSF)动员的骨髓及外周血干细胞,非血缘供者单纯采集外周血干细胞.结果 回输单个核细胞中位数为7.89(4.00-14.21)×10~(8)/kg,所有患者均获供者造血重建,粒细胞植活中位时间14(11～20)d;血小板植活中位时间12(8～108)d.但1例患者发生晚期排斥,行另一供者二次移植后植活.21例次移植后共发生6例次急性GVHD(I度3例,Ⅱ度皮肤3例),发生率16%.19例生存期>100 d的患者中有7例发生慢性GVHD,其中4例为局限型,3例为广泛型.截至2009年2月28 日,经过中位18(2.0～106.8)个月的随访,共有17例患者无病生存,总生存率为82.5%.结论 采用Cy+ATG的预处理方案对SAA患者进行HLA配型相合HSCT,植活率高,可以获得良好的疗效.     

Risk Factors for Cytomegalovirus Retinitis Following Bone Marrow Transplantation From Unrelated Donors in Patients With Severe Aplastic Anemia or Myelodysplasia

Two cases of cytomegalovirus (CMV) retinitis following bone marrow transplantation (BMT) from unrelated donors are reported. 1 patient had been treated for severe aplastic anemia (SAA) and the other for hypoplastic myelodysplastic syndrome (MDS). Because first line therapy with antithymocyte globulin (ATG) and cyclosporin A (CsA) had failed, BMT was performed following a conditioning regimen of ATG, cyclophosphamide, and total lymphoid irradiation. Treatment for CMV retinitis was successfully carried out with gancyclovir (systemic and intraocular injection), foscarnet, and photocoagulation (Case 1) and gancyclovir and foscarnet (Case 2). Both patients also developed Epstein-Barr virus-associated lymphoproliferative disease (EBV-LPD). We compared these 2 cases with 14 SAA patients who did not develop CMV retinitis after BMT using marrow from either HLA-identical siblings (n = 9) or from unrelated donors (n = 5). Unlike the retinitis patients, the latter 5 patients received ATG only once. The retinitis patients had significantly lower CD4+ T-cell levels in their peripheral blood than the 14 patients who did not develop CMV retinitis. We believe that repeated treatment with ATG and transplantation from unrelated donors may lead to immune dysfunction that could increase the likelihood of CMV retinitis, as well as LPD. For such BMT patients, regular ophthalmic examinations and careful testing for CMV antigenemia are recommended.     

Intensive Immunosuppression Therapy for Aplastic Anemia Associated with Dyskeratosis Congenita: Report of a Case

Dyskeratosis congenita (DC) is a very rare inherited disorder characterized by skin pigmentation, nail dystrophy, and mucosal leukoplakia. It is also associated with a variety of noncutaneous abnormalities, such as fatal pulmonary complications, malignancy, and bone marrow failure.We report the case of a 32-year-old man with DC associated with severe aplastic anemia (SAA). The traditional treatment of DC-associated SAA is allogeneic hematopoietic stem cell transplantation (HSCT). However, in this case, an HLA-matched donor was not available. Therefore our patient was given intensive immunosuppressive therapy with antilymphocyte globulin (ALG) and cyclosporine A (CsA). The hemogram findings improved after the treatment, but the patient died of pulmonary complications after being in stable condition for 6 months. The results support the possible use of intensive immunosuppression with ALG and CsA for DC-associated SAA as an alternative treatment for patients who are not eligible for HSCT.     

Stem Cell Transplantation for Aplastic Anemia

Survival of patients with aplastic anemia treated with transplantation of bone marrow has improved significantly over the past several decades. Allogeneic bone marrow transplantation (BMT) for patients with HLA-identical siblings is now the first-line therapy, and long-term survival of approximately 90% can be expected with cyclophosphamide/antithymocyte globulin conditioning and postgrafting methotrexate/cyclosporine immunosuppression. The outcome of unrelated donor BMT has also improved significantly with the identification of a preparative regimen with less toxicity combined with the development of high-resolution DNA-based HLA typing to identify the optimal unrelated marrow donor. Patients with fully HLA-matched unrelated donors should be considered candidates for transplantation prior to exposure to repeat courses of immunosuppression. Future progress in hematopoietic stem cell transplantation for aplastic anemia will be directed toward further decreasing the acute toxicity and decreasing the delayed effects of the conditioning regimens while maintaining highly reliable rates of sustained engraftment with prevention of acute and chronic graft-versus-host disease.     

Successful bone marrow transplantation in children with severe aplastic anemia using HLA-partially matched family donors

Bone marrow transplantation (BMT) using HLA-partially matched family donors has produced disappointing results (25–30% of long-term survivors) in patients with severe aplastic anemia. We describe two children affected by severe aplastic anemia, not responsive to immunosuppressive therapy, who underwent allogeneic bone marrow transplantation using a HLA-partially matched family donor. Both cases presented 2 first class HLA-antigens (A and B) disparity between donor and recipient. The pretransplant conditioning regimen consisted of cyclophosphamide, thoracoabdominal irradiation, cytosine-arabinoside, and antilymphocyte globulin. As graft versus host disease (GVHD) prophylaxis, Cyclosporine-A was administered at usual dosages for 6 months. A full marrow engraftment was observed in both cases. Only grade I acute GVHD, promptly responsive to corticosteroid therapy, developed with no chronic GVHD. Five months after transplant, both children progressively developed hypertension, renal function impairment, thrombocytopenia, and severe normochromic anemia, with erythropoietin serum levels lower than expected for the haematocrit. After antihypertension treatment and supportive therapy, the clinical picture progressively improved, while treatment with recombinant human erythropoietin completely corrected the long-lasting anemia. The two children are alive and well 28 months after the transplant, with a Karnofsky score of 100% and a normal peripheral blood count. The authors suggest that, once immunosuppressive therapy has failed, BMT from donors other than HLA-identical sibling is a feasible approach in children affected by severe aplastic anemia, not having an HLA-identical donor. © 1993 Wiley-Liss, Inc.     

Allogeneic bone marrow transplantation versus chemotherapy in the treatment of childhood acute lymphoblastic leukemia in second complete remission

Seventy-six patients between the ages of 2 and 17 years with acute lymphoblastic leukemia (ALL) achieved a second complete remission induced by polychemotherapy. Twenty-one had an HLA-identical donor and underwent allogeneic bone marrow transplantation (BMT) after conditioning with total body irradiation and cyclophosphamide. The remaining 55 patients lacked a suitable donor and received intensive chemotherapy as treatment. Fifteen patients were excluded from the analysis because they relapsed within 3 months after achieving a second complete remission. Three of the 21 BMT patients died of transplant-related complications and seven relapsed between 90 and 480 days after transplantation. Eleven patients are alive and disease free at 5.5-71 months with an actuarial survival of 47.1%; eight patients are on a plateau extending from 22 to 71 months. Thirty-three patients treated with chemotherapy died from relapse and seven are alive and disease free 7.5-99 months from the second remission, with an actuarial survival of 9%. The probability of survival was significantly higher in the BMT group (p less than 0.025). The probability of remaining in complete remission in the BMT group was 58.5% versus 10.9% in the chemotherapy group (p less than 0.005). Our results show that BMT is the best alternative therapy for children affected by ALL who have had a relapse in the marrow.     

Intensive immunosuppression with antithymocyte globulin and cyclosporine as treatment for severe acquired aplastic anemia

Immunosuppressive therapy can produce hematologic improvement in a large proportion of patients with severe aplastic anemia. Antithymocyte globulin (ATG) is the current treatment of choice for patients who do not have histocompatible sibling donors or who are otherwise inegligible for allogeneic bone marrow transplantation. About 50% of patients respond to an initial course of ATG, and many nonresponders can be salvaged by subsequent treatment with cyclosporine (CsA). To determine whether simultaneous administration of these agents could further improve response rates, we enrolled 55 patients in a therapeutic trial of 4 days of ATG and 6 months of CsA. Among the 51 patients who had not received previous courses of ATG or CsA, 67% had responded by 3 months, and 78% had responded by 1 year (response was defined as an increase in peripheral blood counts sufficient that a patient no longer met the criteria for severe disease). There was a high incidence of relapse (36% actuarial risk at 2 years), but most relapsed patients responded to additional courses of immunosuppression, and relapse was not associated with a significant survival disadvantage. Evolution to myelodysplastic syndromes and acute leukemia was rare (1 of 51 patients), but the later appearance of paroxysmal nocturnal hemoglobinuria was more common (5 of 51 patients). Actuarial survival was 86% at 1 year and 72% at 2 years. These data support the use of a combination immunosuppressive regimen containing both ATG and CsA as first-line therapy for severe aplastic anemia.     

Unusual complications after bone marrow transplantation for dyskeratosis congenita

Dyskeratosis congenita (DC) is a rare inherited disorder often associated with aplastic anaemia. We report the cases of five boys transplanted with an HLA-identical related donor for severe aplastic anaemia (SAA) associated to DC; in all cases successful engraftment was observed. Three patients died 2–8 years after bone marrow transplantation (BMT) with signs of endothelial cell damage syndrome (kidney microangiopathy and liver veno-occlusive disease). Another boy died 1 year after BMT from Evans syndrome and invasive aspergillosis. One boy currently presents anaemia, polyarthritis of unknown origin, pulmonary fibrosis and gut malabsorption 7.5 years after BMT. SAA associated with DC can be successfully treated by allogeneic BMT. However, these early and late complications observed are very unusual after BMT and probably reflect the association of transplanted-related factors, evolution of the underlying disease, and increased sensitivity of endothelial cells. Modified conditioning approaches, advances in supportive care and surveillance of these unusual complications offer the possibility of improved outcome for these patients.     

Allogeneic bone marrow transplantation for agnogenic myeloid metaplasia

Agnogenic myeloid metaplasia is a rare indication for allogeneic bone marrow transplantation (BMT). We have retrospectively studied 12 patients allografted for this disease within the French BMT group. Prior to BMT, the mean age was 40 years (range 14–49). Diagnosis was based on the Polycythaemia Vera Study Group criteria. Before BMT, 10 patients had been splenectomized, eight required transfusions, and four had received at least two lines of chemotherapy. Cyclophosphamide and total body irradiation was the main conditioning regimen used ( n= 8). The donor was an HLA-identical sibling except in one case where there was one HLA-DR mismatch. Acute graft-versus-host disease (GVHD) prophylaxis consisted of methotrexate and cyclosporine A. 11 patients engrafted with median times to achieve absolute neutrophil count > 0.5 × 10⁹/l and platelet count > 50 × 10⁹/l of 17 (range 12–44) and 29 (range 12–196) days respectively. One primary graft failure occurred. 10 patients developed grade II–IV acute GVHD, four developed extensive chronic GVHD. One patient relapsed 16 months post-BMT and was untreated and well 14 months later. Three patients died from the BMT procedure. In May 1996 the median follow-up was 25 months and the 4-year overall and event-free survivals were 71% and 59%, respectively. Thus, we conclude that extensive myelofibrosis is not associated with delayed engraftment, and that HLA-identical sibling allogeneic BMT can be considered in a small proportion of patients with agnogenic myeloid metaplasia.     

In vitro evidence for disappearance of erythroid progenitor T suppressor cells following allogeneic bone marrow transplantation for severe aplastic anemia

In vitro coculture studies were performed in five patients with severe aplastic anemia (SAA) and their normal HLA-matched donors before and after allogeneic bone marrow transplantation (BMT) to determine whether the erythropoietic function of T cells is abnormal in this disorder. These coculture studies used fresh or cryopreserved marrow T lymphocytes with fresh or cryopreserved marrow T cell-depleted target cells. Four of five aplastic patients had little or no transfusion exposure before studies. The composite results showed that, in comparison to the erythropoietic effects of normal HLA-identical marrow T lymphocytes or engrafted T lymphocytes, T lymphocytes collected from the aplastic patients before BMT consistently suppressed or failed to support CFUE and BFUE growth optimally from autologous marrow, HLA- identical marrow, or engrafted aplastic T cell-depleted marrows. This T cell abnormality was not observed in four multiply transfused leukemics and three patients with myelodysplastic syndrome. Marker analyses of SAA marrow T lymphocytes performed before and after BMT suggested that the erythropoietic functional abnormality was due to abnormal marrow T cell composition reflecting an excess of activated Tac+, T3+, T11+ lymphocytes. Collectively, these in vitro studies provide firmer in vitro evidence implicating T cells in the pathogenesis of SAA. The erythropoietic T cells abnormalities in SAA are fully corrected by allogeneic BMT.