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EXPERIMENTAL BASIS AND CLINICAL OBSERVATIONS: Remission of an autoimmune disease has been observed in certain patients after bone marrow allograft from a healthy donor. Autoimmune disease in the donor can also be transmitted to an unaffected recipient. These phenomena would be hematopoietic-dependent. BONE MARROW ALLOGRAFTS: Indications for the treatment of refractory autoimmune diseases are exceptional due to the related mortality even in patients without malignant hematologic disease. A NEW THERAPEUTIC CONCEPT: Therapeutic intensification, followed with autologous peripheral stem cell grafts, a procedure with a mortality below 3% in 1997, constitutes a therapeutic alternative in these difficult indication concerning severe refractory autoimmune diseases including: sclerodermia, vasculitis, lupus, inflammatory myositis, autoimmune cyopenia.

We have analyzed factors influencing the outcome of 102 children with acute leukemia given a cord blood transplantation (CBT) and reported to the Eurocord Registry. Seventy patients with acute lymphoblastic and 32 with acute myeloid leukemia were given either a related (n = 42) or an unrelated (n = 60) CBT. Children given CBT during first or second complete remission were considered as belonging to the good-risk group (n = 66), whereas those who received a transplant in a more advanced stage of disease were assigned to the poor-risk group (n = 36). In the related group (RCBT), 12 of 42 patients received transplantation from an HLA-disparate donor, whereas in the unrelated group (UCBT) 54 of 60 received an HLA mismatched CBT. Kaplan-Meier estimates for neutrophil recovery at day 60 were 84% +/- 7% in RCBT and 79 +/- 6% in UCBT (P =.16). In multivariate analysis, the most important factor influencing neutrophil engraftment in UCBT was a nucleated cell dose infused greater than 3.7 x 10(7)/kg (P =.05, relative risk [RR] of 1.85, 95% confidence interval [CI]: 0.98-3.4). The incidence of grade II through IV acute graft-versus-host disease was 41% +/- 8% in the RCBT group and 37% +/- 6% in the UCBT group (P =.59). Kaplan-Meier estimates of 2-year event-free survival (EFS) after RCBT or UCBT were 39% +/- 8% and 30% +/- 7%, respectively (P =.19). In multivariate analysis, the most important factor influencing EFS was disease status at time of transplantation: good-risk patients had a 2-year EFS of 49% +/- 7% as compared to 8% +/- 5% in patients with more advanced disease (P =.0003, RR: 0.40, 95% CI: 0.24 to 0. 65). This was a consequence of both an increased 1-year transplant related mortality and a higher 2-year relapse rate in the poor-risk group (65% +/- 9% and 77% +/- 14%, respectively), as compared with good risk patients (34% +/- 6% and 31% +/- 9%, respectively). These data confirm that allogeneic CBT from either a related or an unrelated donor is a feasible procedure able to cure a significant proportion of children with acute leukemia, especially if transplanted in a favorable phase of disease.

Agnogenic myeloid metaplasia (AMM) is a chronic myeloproliferative disorder in which patients with poor prognostic features, receiving conventional treatments, have a median survival of less than 3 years. In this retrospective multicenter study, we analyze the results and try to define the indications for allogeneic stem cell transplantation in AMM. From January 1979 to November 1997, 55 patients with a median age of 42 years were transplanted from HLA-matched related (n = 49) or alternative (n = 6) donors for AMM. A multivariate analysis was conducted to identify factors associated with posttransplant outcome. The median posttransplant follow-up was 36 months (range, 6 to 223). The 5-year probability of survival was 47% +/- 8% for the overall group, and 54% +/- 8% for patients receiving an unmanipulated HLA-matched related transplant. The 1-year probability of transplant-related mortality was 27% +/- 6%. Hemoglobin level/=100 g/L and osteomyelosclerosis before transplant adversely affected the outcome. The probability of developing grade III-IV acute graft-versus-host disease (GVHD) was 33% +/- 8%. Sixteen of 45 patients developed extensive chronic GVHD. At last follow-up, 22 patients were in complete histohematologic remission. Treatment failure was observed in 13 cases. Age at transplant and karyotype were predictors of treatment failure. Allogeneic stem cell transplantation is an effective treatment leading to cure in a substantial number of patients with AMM. A better characterization of the variables affecting the posttransplant outcome should lead to a decreased transplant-related mortality and an improvement in these results.

To determine prognostic factors for survival in bone marrow transplant recipients with invasive aspergillosis (IA), we retrospectively reviewed 27 IA cases observed in our bone marrow transplantation unit between January 1994 and October 1994. On 30 September 1997, six patients were alive and disease-free. The median survival after IA diagnosis was 36 days. Of eight variables found to be related to survival according to the univariate analysis, graft-versus-host disease (GVHD) status at IA diagnosis (P = .0008) and the cumulative prednisolone dose taken during the week preceding IA diagnosis (CPDlw) (P.0001) were selected by a backward stepwise Cox regression model. A three-stage classification was established: CPD1w ofor =7 mg/kg (3 of 8 patients died; 60-day survival rate, 88%), CPD1w of7 mg/kg and no GVHD (9 of 10 patients died; 60-day survival rate, 20%), and CPD1w of7 mg/kg and active acute grade 2 or more or extensive chronic GVHD (9 of 9 patients died; 30-day survival rate, 0) (P.0001).

T cells present in an allogeneic bone marrow transplant may produce graft-versus-host disease but also contribute to immune reconstitution and enhance engraftment. Our aim was to separate alloreactive from nonalloreactive T lymphocytes, by performing a mixed lymphocyte culture (MLC) stimulation of donor cells, followed by selective depletion of activated cells expressing the high-affinity interleukin 2 receptor. We then characterized the resulting depleted cell fraction.Donor peripheral blood mononuclear cells were cocultured with irradiated peripheral blood mononuclear cells from HLA-nonidentical recipient stimulators in an MLC. After 3 days, CD25+ lymphocytes (alloreactive cells expressing the alpha chain of the interleukin 2 receptor) were removed by immunomagnetic separation. The depleted donor fraction and untreated cells were then rechallenged in a secondary MLC with the original irradiated stimulator cells or a third party to assess relative alloreactivity.Inhibition of the secondary MLC and of host-specific cytotoxic activities was observed as well as a disappearance of interleukin 2 receptor-positive cells. Alloreactivity against unrelated third-party cells was preserved. Limiting dilution analysis of residual alloantigen-reactive T lymphocytes demonstrated a 1.3 log reduction of antihost reactivity. The depletion largely removed host-specific alloreactive CD4+ cells.This method reduces alloreactivity while retaining reactivity against third-party targets. This approach may allow therapeutic infusion of T cells after HLA-nonidentical allografts with a reduced capacity to produce graft-versus-host disease.

Dyskeratosis congenita (DC) is an inherited disorder characterized by skin pigmentation, nail dystrophy and mucosal leucoplakia. In 1995 a Dyskeratosis Congenita Registry was established at the Hammersmith Hospital. In the 46 families recruited, 76/83 patients were male, suggesting that the major form of DC is X-linked. As well as a variety of noncutaneous abnormalities, the majority (93%) of patients had bone marrow (BM) failure and this was the principal cause (71%) of early mortality. In addition to BM hypoplasia, some patients also developed myelodysplasia and acute myelod leukaemia. Pulmonary abnormalities were present in 19% of patients. In affected females the phenotype was less severe. Some female carriers of X-linked DC had clinical features. Carriers of X-linked DC showed skewed X-chromosome inactivation patterns (XCIPs), suggesting that cells expressing the normal DC allele have a growth/survival advantage over cells that express the mutant allele. Linkage analysis in multiplex families confirmed that the DKC1 gene, responsible for the X-linked form of DC, is located within Xq28 and facilitated its positional cloning. The high incidence of BM failure in association with a wide range of somatic abnormalities together with the ubiquitous expression of DKC1 suggest that, as well as having a critical role in normal haemopoiesis, this gene has a key role in normal cell biology.

Allogeneic bone marrow transplantation is widely used for the treatment of various hematologic disorders. The results are quite reproducible from center to center with a mean disease-free survival of 50%, which varies from 10% in patients transplanted in relapse to 70% in young patients transplanted in first complete remission or in the chronic phase of chronic myeloid leukemia. Relapse is one of the main complications, and its frequency increases with disease status and the use of T cell depletion and the subsequent loss of the graft versus leukemia effect of traransplanted ogeneic cells. New agents such as high dose ARA-C, VP 16, Myleran, and Melphalan have been studied in Phase I–II studies. Different modalities of total body irradiation, that is, single dose or fractionated or hyperfractionated doses, have been used. None of these new modalities has modified significantly the long-term disease-free survival rate because of the toxicity of any attempt to diminish the rate of relapse with intensified regimens. Single dose total body irradiation of 10 Gy seems to reduce the risk of leukemic relapse when compared with 12 Gy fractionated total body irradiation, especially when the marrow is T depleted.

We describe the long-term follow-up of 50 Fanconi's anaemia patients who were transplanted from a related donor with a median follow-up of6 years. The survival estimate was 74.4% at 54 months and 58.5% at 100 months. All patients were conditioned with low-dose cyclophosphamide and thoraco-abdominal irradiation. Acute graft-versus-host disease (GvHD) of grade II or more developed in 26 patients and chronic GvHD developed in 30/43 (69.9%) patients. The survival of patients without chronic GvHD (n = 13) was 100%. In addition to chronic GvHD, 20 pre-transplant transfusions was shown to have an adverse impact on survival by multivariate analysis (relative risk = 7.08, P = 0.0003). Prospective follow-up of growth and endocrine function could be performed in 31 patients. Of 20 boys, six have already reached normal puberty within the expected time. Among the 11 girls, three were at the pubertal age at the time of analysis. Growth retardation was common, whereas late complications (e.g. peripheral hypothyroidism, cataract) were rare. However, the most important long-term complication was the occurrence of cancer in seven patients (8-year projected incidence 24%). Among the 32 survivors, 27 (84.5%) had a normal and four a moderately reduced performance status, and all achieved complete engraftment with donor cells. Therefore transplantation was able to cure these patients who remain at high risk for developing late complications. Clearly, a genetic predisposition and chronic GvHD could have led to the development of these cancers. However, we cannot completely rule out irradiation as a cofactor in the genesis of these cancers, and therefore no longer use irradiation for the conditioning of Fanconi's anaemia patients.

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.

This study aimed to demonstrate that sufficient Ph-negative blood progenitors could be collected following administration of glycosylated rhG-CSF (lenograstim) to patients with Philadelphia chromosome (Ph)-positive chronic myeloid leukaemia (CML) who responded to recombinant alpha-interferon (alpha-IFN) (Ph-positive marrow metaphases35%). 23 patients received lenograstim (150 microg/m2) once daily for a median of 9 d. Peak circulating numbers of white blood cells (36.4 x 10(9)/l), CD34+ cells (24/ microl) and colony-forming unit-granulocyte-macrophage (CFU-GM; 1346.5/ml) occurred at a median of day 8, day 8 and day 7, respectively. Two to six (median three) leukaphereses (LK) were performed from days 5 to 12. The median number of mononuclear cells (MNC), CD34+ cells and CFU-GM collected per patient was 7.35 x 10(8/)kg, 2.72 x 10(6)/kg and 10.23 x 10(4)/kg, respectively. 22/23 patients had LK which contained either 10(4) CFU-GM/kg and/or 10(6) CD34+ cells/kg; 47LK (from 20/22 patients) were evaluable for cytogenetics. The median percentage of Ph-positive cells was 0, and 43/47 LK (91%) contained35% Ph-positive cells; 25 (53%) were entirely negative. Sixteen of 20 evaluable patients had one or more LK with35% Ph-positive cells, and 12 had at least one 100% Ph-negative LK. Mobilization and collection of Ph-negative cells were not influenced by the dose or duration of alpha-IFN administration before (or during) lenograstim administration or by the quality of cytogenetic response (complete v major) during lenograstim administration. No significant side-effects were observed. Thus, lenograstim administration can result in satisfactory Ph-negative blood progenitor cell collection. Autologous transplantation of such cells may be used when indicated.

Over the past decade, allogeneic cord blood transplantation (CBT) has been widely used for treating patients with malignant disorders. However, the reported low incidence of GVHD observed after allogeneic CBT might be a major drawback in leukemic recipients and at present it is not clear whether CBT really predisposes patients to an increased risk of leukemia relapse. In order to further elucidate the role of CBT in children with hematological malignancies, 54 patients with ALL or AML given either a related (31 cases) or an unrelated (23 cases) CBT in 25 centers participating in the Eurocord Registry were analyzed. Overall survival of related and unrelated CBT recipients was substantially similar, the most important factor influencing patients' outcome being disease state at time of transplantation. In fact, due to a markedly increased relapse rate, poor-risk children (ie patients transplanted in more advanced disease) experienced a significantly worse EFS than those given CBT in a more favorable disease phase (ie CR1 or CR2). These data confirm that allogeneic CBT from either a related or an unrelated donor is a feasible procedure able to cure a significant proportion of children with acute leukemia, especially if transplanted in a favorable phase of disease.

Umbilical cord blood T cells are less functional. Different explanations have been proposed. In this study we analyze the Vbeta T cell cord blood repertoire. All the Vbeta families are expressed. We found only the overexpression of three Vbeta: Vbeta 5-1, Vbeta 5-2, Vbeta 21-2.

Eurocord Transplant has established a registry for studying results of cord blood transplant. We have analyzed 78 patients who have received a related CBT between October 1988 and December 1996. The median follow-up time was 29 months (1-99). The median age was 5 years (0.2-20), median weight 19 kg (5-50). Forty-six patients had a malignant disease: 32 acute leukemia (AL), six chronic myeloid leukemia (CML), four myelodysplastic syndrome, two neuroblastoma and two non-Hodgkin lymphoma. Thirty-two patients were transplanted for non-malignant diseases including 17 bone marrow failure syndromes (BMFS), three sickle cell anemia, five thalassemia and seven inborn errors. The donor was an HLA-identical sibling in 60 cases and an HLA-mismatched donor in 18 cases. As conditioning, 36 patients received irradiation and 40 patients received associated busulfan-containing regimens. GVHD prophylaxis consisted of CsA alone in 36 cases, CsA associated with prednisone in eight cases, CsA, methotrexate (Mtx) with or without prednisone in 28 cases and CsA with monoclonal antibody or ATG in four cases. The median number of nucleated cells (NC) infused/kg was 3.9 x 10(7) (0.7-15). One-year survival was 63 +/- 6%. Age, weight, HLA identity and negative cytomegalovirus (CMV) serology in the recipient were significant favorable prognostic factors. Among these 78 patients, the incidence of gradeor = II GVHD was 9% in HLA-matched CBT and 50% in mismatched CBT (P0.001). Neutrophil engraftment was associated with age6 years (P = 0.02) and weight20 kg (P = 0.02). It was 73% in patients receiving3.7 x 10(7) nucleated cells (NC) infused/kg and 85% in patients receiving more (P = 0.06). Favorable factors for platelets engraftment were age6 years (P = 0.03), weight20 kg (P = 0.002) and HLA identity (P0.0001). Related cord blood transplantation offers a good alternative to BMT. Theses results are in favor of freezing cord blood in families in whom a transplant might be indicated.

Patients with beta-thalassemia (Hbeta th) and sickle cell anemia (SCA) can be treated with bone marrow transplantation. Stem cells from cord blood have several theoretical advantages, however, the place of cord blood transplant for hemoglobinopathies has not yet been established. We report here the EUROCORD experience of 10 patients (Hbeta th = 7, SCA = 3) transplanted with related cord blood.

This report summarizes the results of unrelated cord blood transplants. Sixty-five patients were reported to Eurocord. One year survival was 29%. Factors associated with survival were diagnosis, inborn errors had a better survival than leukemia or aplastic anemia; higher number of cells infused and negative pre-transplant CMV serology were also favorable factors. Granulocyte and platelet engraftment were associated with a higher number of nucleated cells infused, GVH incidence was low especially in CMV negative patients, it was not associated with the degree of HLA disparity. These results were similar to other series reported in the USA and showed the benefit of using mismatched unrelated cord blood in clearly defined situations.

The number of cord blood transplants has been increasing very quickly with more than 250 cases reported to Eurocord Registry and more than 500 patients transplanted via the New York Cord Blood Bank. Cord blood transplants have been performed either with related or unrelated cord blood. Several cord blood banks established a group called Netcord whose goal is the standardization of the procedures, the organization of internal audits for accreditation and qualification, and the communication and exchange by internet of donor search on an international basis. More than 15,000 units of frozen cord blood are currently available and this number is increasing rapidly worldwide. Analysis of the clinical results has shown that related cord blood transplants give better results than unrelated cord blood transplants. Factors associated with better survival in related and unrelated cord blood transplants were lower age, diagnosis, with better results in inborn errors and in good risk children with acute leukemia. A larger number of nucleated cells in the transplant and the recipient being negative for CMV serology were also favourable risk factors for survival. Engraftment was improved with higher numbers of cells and HLA identity. Graft versus Host disease was reduced when compared to transplants of adult allogeneic bone marrow or peripheral blood progenitor cells. HLA disparities did not influence GVH; the only factor associated with increased GVH was positive CMV serology in the recipient. This study shows that cord blood is an alternative source of hematopoietic stem cells for allogeneic transplantation in children and in some adults. HLA disparity is not a limiting factor but the number of cells infused is important; currently the use of a number of nucleated cells inferior to 1 x 10(7)/kg is not recommended. Several questions remain including the criteria of choice of the donor, the indications in children and in adults, the comparison of cord blood transplants to other sources of hematopoietic stem cells and the role of growth factors and expansion for improving the speed of engraftment.

Cells contained in umbilical cord blood collected after birth can be cryopreserved and used for hematopoietic stem cells transplantation in patients with severe hematological disorders. The first success has led to the development of cryopreserved umbilical cord blood banks. More than 500 cord blood transplant have been reported and more than 10,000 cord blood have been stored for use in unrelated and related matched and mismatched transplants. European results show that the number of hematopoietic stem cells present in one cord blood is sufficient to permanently engraft most of the patients. Graft versus host disease is decreased even in unrelated mismatched transplants.

Fanconi anaemia is a hereditary disorder characterised by chromosomal breaks increased by cross-linking agents. Bone marrow transplantation is the treatment of choice when a HLA identical sibling donor has been identified. The use of low-dose cyclophosphamide with thoraco-abdominal irradiation for the conditioning regimen of FA patients has lead to a dramatic improvement of survival, with a long-term survival of 75% at our institution. However, if most patients are completely cured of their haematological disease, there is concern about an increased frequency of secondary tumours, mostly head and neck squamous cell carcinomas of poor prognosis. Results of BMT using alternative donors (HLA mismatched related and unrelated donors) have also improved during the last decade. A better selection of the donor via high-resolution techniques for class-II HLA matching, and more recently the use of T cell depleted grafts are probably the main explanations. Despite a short follow-up and the small number of patients analysed, transplants using HLA matched family cord blood give some promising results. On the other hand, first results with unrelated cord blood remind that this approach is clearly an experimental one that has to be evaluated through international registries and prospective studies. New approaches including autologous stem cell transplantations and gene therapy are currently explored.

Secondary malignancies (lymphomas, leukemias, and solid tumors) occurring after bone marrow transplantation are now more frequently reported, as the patients surviving the early phase of the graft and remaining free of their original disease are more numerous. Besides early Epstein-Barr virus-associated B-cell lymphoproliferative diseases, which are the most common type and most often of donor origin, few late-occurring lymphomas have been described that might represent a distinct entity. We report here a case of Hodgkin's disease developing 8 years after allogeneic bone marrow transplantation for chronic myelogeneous leukemia. Only two Hodgkin's diseases after allogeneic bone marrow transplantation have been reported in the literature so far. The case we report is of interest because of its donor origin and its association with Epstein-Barr virus infection.

EUROCORD registry has collected more than 140 cases of cord blood transplant. Among the first 85 patients, 53 were transplanted for an hematologic malignancy including 36 acute leukemia, 21 in 1st and 2nd CR and 15 in > than CR2 or resistant relapse, 5 chronic myeloid leukemia in CP1, 1 in CP2, 1 in CP3 and 1 in BC, 5 myelodysplastic syndrome (1 transformed in AL), 2 non Hodgkin lymphoma and 2 neuroblastoma. The 1 year survival was 43% with a median follow-up time of 250 days; in related transplants, it was 48% and in unrelated 41% with a shorter follow-up. Good survival was associated with age 3.7 × 107/kg p = 0.009 and standard risk leukemia. Patients transplanted for leukemia in CR1 and CR2 had a survival of 56% while patients transplanted in later phase had 8% survival. 82% of the patients reached > 500 PMN at day 45, 7 patients died earlier. Engraftment was associated with the number of cells infused, age and weight. GVH grade II–IV was observed in 52.5% of the cases, it was usually mild. Leukemic relapse was observed in 11 cases, 3 AML, 5 ALL, 2 MDS, and 1 CML. 8 patients transplanted in advanced disease relapsed early, 3 patients relapsed later and are still alive either after donor lymphocyte transfusions or a second BMT. The primary causes of death were rejection, leukemic relapse, or transplant related toxicity. This study shows that related and unrelated match or mismatched cord blood transplant is a good source of hematopoietic stem cells in patients with hematological malignancies.

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 count0.5 x 10(9)/l and platelet count50 x 10(9)/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.

Cord-blood banks have increased the use of cord-blood transplantation in patients with hematologic disorders. We have established a registry containing information on the outcome of cord-blood transplantation.We sent questionnaires to 45 transplantation centers for information on patients receiving cord-blood transplants from 1988 to 1996. Reports on 143 transplantations, performed at 45 centers, were studied, and the responses were analyzed separately according to whether the donor was related or unrelated to the recipient.Among 78 recipients of cord blood from related donors, the Kaplan-Meier estimate of survival at one year was 63 percent. Younger age, lower weight, transplants from HLA-identical donors, and cytomegalovirus-negative serologic results in the recipient were favorable prognostic factors. Graft-versus-host-disease of at least grade II occurred at estimated rates of 9 percent in 60 recipients of HLA-matched cord blood and 50 percent in 18 recipients of HLA-mismatched cord blood. Neutrophil engraftment was associated with an age of less than six years (P = 0.02) and a weight of less than 20 kg (P = 0.02), and it occurred in 85 percent of patients receiving 37 million or more nucleated cells per kilogram of body weight. Among 65 patients who received cord blood from unrelated donors, the Kaplan-Meier estimate of survival at one year was 29 percent. Cytomegalovirus-negative serologic status in these recipients was associated with improved survival (P = 0.03) and was the most important predictor of graft-versus-host disease (P = 0.04). Neutrophil recovery occurred in 94 percent of the patients who received 37 million or more nucleated cells per kilogram from unrelated donors.Cord blood is a feasible alternative source of hematopoietic stem cells for pediatric and some adult patients with major hematologic disorders, particularly if the donor and the recipient are related.

Allogeneic transplantation of cytokine-mobilized peripheral blood stem cells (PBSCs) is now being increasingly performed, but safety considerations for hematologically normal PBSC donors have not been fully addressed. Progenitors are generally mobilized for collection from normal donors using recombinant human granulocyte colony-stimulating factor (rhG-CSF). Although the short-term safety profile of rhG-CSF seems acceptable, experience remains limited and its optimal dose and schedule have not been defined. Minimal data exist regarding long-term safety of rhG-CSF, primarily derived from experience in patients with chronic neutropenia or cancer. An "ad hoc" workshop was recently convened among a group of investigators actively involved in the field of allogeneic stem cell transplantation to discuss the safety issues pertaining to normal PBSC donors. There was agreement on the following points: (1) On the basis of available data, it appears that rhG-CSF treatment and PBSC collection have an acceptable short-term safety profile in normal donors. However, the need for continued safety monitoring was recognized. (2) rhG-CSF doses up to 10 microg/kg/d show a consistent dose-response relationship with the mobilization (and collection) of CD34+ progenitor cells, and this dose is acceptable for routine clinical use. Whether higher doses are superior (or cost effective) remains to be determined, and they may produce more severe side effects. The potential risks of marked leukocytosis (arbitrarily defined as a leukocyte count of more than 70 x 10(9)/L) have been a concern, and rhG-CSF dose reduction is performed by many centers to maintain leukocyte counts below this level. (3) Transient post donation cytopenias, involving granulocytes, lymphocytes, and platelets, may occur and are at least partly related to the leukapheresis procedure. These are generally asymptomatic and self-limited; follow-up blood counts are not necessarily required. Reinfusion of autologous platelet-rich plasma should be considered for donors with expected postdonation thrombocytopenia (platelet count80 to 100 x 10(9)/L). (4) Donors should meet the eligibility criteria which apply to donors of apheresis platelets, with the exception that pediatric donors may also be considered. Any deviation from these criteria should have supporting documentation. There is insufficient information at this time to clearly establish definite contraindications for PBSC collection in a hematologically normal donor. Potential contraindications include the presence of inflammatory, autoimmune, or rheumatologic disorders, as well as atherosclerotic or cerebrovascular disease. (5) The creation of an International PBSC Donor Registry is desirable to facilitate monitoring the long-term effects of the procedure. Individual institutions or donor centers are encouraged to establish their own PBSC donor follow-up system, preferably with a standardized approach to data collection.

Bone marrow transplants for severe aplastic anemia were first performed in the 1970s. Transplant regimens, supportive care, and patient selection have changed substantially since then. Our objective was to determine the impact of these changes on transplant outcome. We studied 1,305 recipients of HLA-identical sibling transplants for aplastic anemia between 1976 and 1992, reported to the IBMTR by 179 centers. We compared survival of transplants performed in three intervals (1976 through 1980 [n = 186], 1981 through 1987 [n = 648], and 1988 through 1992 [n = 471]) using Cox proportional hazards regression. Five-year survival (+/-95% confidence interval) increased from 48% +/- 7% in the 1976-1980 cohort to 66% +/- 6% in the 1988-1992 cohort (P.0001). Risks of graft-versus-host disease (GVHD) and interstitial pneumonia decreased over time, but the risk of graft failure did not. Higher long-term survival resulted primarily from decreased mortality in the first 3 months posttransplantation. Late mortality risks were low and changed little over the intervals studied. In multivariate analysis, changes in transplantation strategies accounted for most but not all of the improved outcome. Use of cyclosporine to prevent GVHD was the most important factor. Changes in patient selection did not seem to explain improved survival. Survival after HLA-identical sibling bone marrow transplantations for aplastic anemia has improved since 1976. Changes in GVHD prophylaxis account for much of this improvement. Other changes may also operate.

One hundred and ninety-one patients with acute leukaemia who received bone marrow from HLA-A, -B and -DR identical unrelated donors and were reported to EBMT and/or IMUST, were matched with 382 patients receiving autologous bone marrow for diagnosis, age, stage of disease and year of transplantation. Transplant-related mortality (TRM) was significantly higher in recipients of unrelated marrow compared to autograft recipients, 44 +/- 4% (+/- 95% confidence interval) and 15 +/- 3% at 2 years in the two groups, respectively (P10(-4)). In contrast, relapse probability was lower in recipients of unrelated marrow, being 32 +/- 5% at 2 years compared to 55 +/- 3% in recipients of autografts (P10(-4)). Two-year leukaemia-free survival (LFS) in patients with acute lymphoblastic leukaemia was 39 +/- 5% and 32 +/- 3% in the two groups, respectively. Among patients with acute myeloid leukaemia (AML), the corresponding figures were 36 +/- 6% and 46 +/- 5% in the two groups, respectively (P = NS). In AML in first remission (CR-1), the 2-year survival was 42 +/- 10% in recipients of unrelated bone marrow, compared to 69 +/- 8% in autograft recipients (P = 0.008). When all patients with acute leukaemia were included, the 2-year LFS was 38% in recipients of unrelated marrow, compared to 37% in autograft recipients (NS). In conclusion, this retrospective analysis supports the design of a prospective randomized study in patients with high-risk/advanced acute leukaemia who lack a suitable related bone marrow donor, to ascertain which of the two strategies, if any, should be favoured.

Approximately 25% of patients with Fanconi anemia (FA) have evidence of spontaneously occurring mosaicism as manifest by the presence of two subpopulations of lymphocytes, one of which is hypersensitive to cross-linking agents (e.g. mitomycin C) while the other behaves normally in response to these agents. The molecular basis of this phenotypic reversion has not yet been determined. We have investigated 8 FA patients with evidence of mosaicism. Epstein-Barr virus-immortalized lymphoblastoid cell lines established from these patients exhibited an IC50 for mitomycin C of 25 to100 nM compared to a mean of 2 +/- 2 nM for 20 nonmosaic FA patients and 49 +/- 11 nM for 8 healthy controls. In 3 patients who were compound heterozygotes for pathogenic FAC gene mutations the molecular mechanism of the mosaicism was investigated by haplotype analysis. The results indicated that an intragenic mitotic recombination must have occurred leading to a segregation of a wild-type allele in the reverted cells and suggested two patterns of recombination. In 1 patient a single intragenic crossover between the maternally and paternally inherited mutations occurred associated with markers located distally to the FAC gene; in the other 2 patients (sibs) the mechanism appears to have been gene conversion resulting in segregants which have lost one pathogenic mutation. In 6 of the 8 patients the hematological symptoms were relatively mild despite an age range of 9-30 years.

Allogeneic BMT for patients with acute myeloid leukemia (AML) is presently a reference therapy. The indications for this therapy mainly rely upon prognostic factors, and their importance is constantly reassessed. To examine the impact of time from diagnosis to transplant on survival and leukemia-free survival (LFS), we analyzed 109 patients from the database of the SFGM comprising patients who had all received an HLA-identical allogeneic BMT for a diagnosis of AML in first complete remission (CR1) between January 1987 and December 1992. All patients were conditioned with cyclophosphamide (CY) and total body irradiation (TBI) (CYTBI), and methotrexate (MTX) + cyclosporin A (CsA) were used as graft-versus-host disease (GVHD) prophylaxis. Patient characteristics were: age = 33 +/- 9, M/F = 64/45, white blood cell count (WBC) at diagnosis = 27 +/- 42 x 10(9)/l, FAB distribution: M1 and M2 = 55; M3 = 15, M4 and M5 = 33, M0, M6 and M7 = 6. Karyotyping was carried out for 64 patients: 32 had a normal karyotype, 16 had good prognosis abnormalities (t(8;21), t(15;17), inv 16) and 16 patients had other abnormalities. Eleven patients needed two courses of induction to achieve CR. Time between diagnosis and BMT was 120 (64-287) days. Forty-nine patients developed gradeor = 2 acute GVHD (actuarial probability = 46%). With a median follow-up of 50 months (27-100), the 5-year probabilities for transplant-related mortality (TRM), relapse, overall survival and LFS are respectively 25%, 26%, 59% and 55%. A multivariate analysis showed that survival is adversely influenced by three independent factors: time to transplant (120 days vsor = 120 days), acute GVHD (grade 2-4 vs grade 0-1) and age (33 vsor = 33). LFS is only influenced by the first two of these factors. The favorable impact of a shorter time from diagnosis to transplant should lead to performing the transplant as early as possible. Practically speaking, this means that when such therapy is chosen for a patient with CR1 AML, the search for an allogeneic donor should begin immediately and transplant be performed as soon as possible.

Extension of allogeneic transplants to older patients has been limited by a high risk of transplant-related death and graft-versus-host disease. To evaluate the feasibility in older patients, a retrospective analysis of the procedure was performed for first remission acute leukemia in 192 patients aged over 40 years and compared with a group of 1119 recipients aged from 16 to 40 years reported to the EBMT from 1986 to 1992. Patient-, disease-, and treatment-related variables were compared between the two age groups using the chi2 statistical method for categorical variables. Variables differing significantly or recognized as potential prognostic factors were included in a multivariate analysis. Leukemia-free survival and relapse were comparable among the age groups in the two types of leukemias. Incidence of graft-versus-host disease was higher in the older group of ALL patients. Older patients with AML in first remission had a higher treatment-related mortality incidence, with no influence on survival. A pair-matched analysis of AML patients did not show any statistical difference in the probability of LFS, RI, TRM, and survival for the two age cohorts of patients. These results suggest that BMT should be considered for patients over 40 years of age.

Recipients of HLA-matched, related or unrelated allogeneic BMT who were CMV seropositive or those receiving unmanipulated marrow from a seropositive donor were randomised to receive one of three treatment regimens, i.v. acyclovir 500 mg/m2 three times a day from 5 days before transplant to 30 days after transplant followed by oral acyclovir 800 mg four times a day for a further 6 months, i.v. acyclovir followed by placebo, or 400 mg oral acyclovir four times a day followed by placebo (control). This paper reports the 1 year data on the same cohort of patients which was previously reported. Intravenous acyclovir (i.v./PCB) significantly reduced the risk of CMV infection when compared to the control group. The frequency of adverse events reported was comparable among the three groups. The mortality rate was significantly reduced by the sequential use of i.v. acyclovir followed by oral acyclovir, resulting in a 19% survival advantage at 1 year from transplant.

Liver veno-occlusive disease is a severe toxic effect observed after bone marrow transplantation. Clinical manifestations are jaundice, painful liver enlargement, and fluid-sodium retention. Histologically there is non-thrombotic obliteration of the centro-lobular veins associated with centro-lobular necrosis. This severe complication of bone marrow transplantation occurs early and is caused by a toxic processing effect. Incidence is variable, 2 to 50% in reported series, depending on patients, type of marrow provessing and on diagnostic criteria (which hinders comparison between studies). According to most studies, veno-occlusive disease regresses spontaneously. Mortality, depending on the severity of the symptoms, varies from 20 to 50%. Pathogenesis remains under debate: the initial event would occur in the sinusoid endothelium creating a state of local hypercoagulability by release of tissue factors favoring deposit of coagulation factors, especially factor VIII, in the subendothelial region of the veinules. There is also a direct toxic effect on centro-lobular hepatocytes which is further aggravated by ischemia and venous stasis. use of heparin to prevent veno-occlusive disease was proposed by the Besançon group in 1985 after they observed a low incidence (1 case in 65) in patients who were given low doses of heparin to maintain patent central catheters. The same team confirmed in 1992 the low incidence in a large retrospective series of 444 patients given either an autograft (3 cases in 253 patients, i.e. 1.2%), or an allograft (5 cases in 191 patients, i.e. 2.6%). Two single-center studies, one in Seattle and the other at the Saint-Antoine hospital in Paris, published in 1990 and 1991, did not show any difference in patients given heparin or not. Inversely, a randomized study published by Attal in 1992 including 161 patients showed a significant difference in the incidence of veno-occlusive disease between patients given heparin (2.5%) and those who were not given heparin (13.7%; p0.01). All these studies show that with low doses (100-150 U/kg) the risk is very very low. The mechanism of action of heparin would appear to be related to its protective effect on the endothelium rather than its hemostasis effect. The vascular protective effect of prostaglandin E1 suggests it might also be useful in preventing veno-occlusive disease.

There is controversy whether adults with acute myelogenous leukemia (AML) in first remission are best treated with chemotherapy or an HLA-identical sibling bone marrow transplant. We studied 1097 adults, 16-50 years old, with AML in first remission. Results of transplants from HLA-identical siblings reported to the International Bone Marrow Transplant Registry (IBMTR; n = 901) were compared with results of chemotherapy in comparable persons treated by the German AML Cooperative Group (GAMLCG; n = 196). Preliminary analyses identified subject- and disease-related variables differing between the cohorts and associated with treatment outcome within each cohort. We adjusted for these variables and differences in time-to-treatment in subsequent comparisons of treatment-related mortality, relapse, survival and leukemia-free survival (LFS). Five-year probability of treatment-related mortality was greater for transplants than chemotherapy (43% (95% confidence interval, 37-49%) vs 7% (3-11%); P0.0001). Five-year relapse probability was less for transplants than chemotherapy (24% (20-28%) vs 63% (55-71%); P0.0001). Five-year probability of survival was similar with transplants and chemotherapy (48% (43-53%) vs 42% (33-51%); P = 0.24). Five-year LFS probability was higher for transplants than chemotherapy (46% (42-50%) vs 35% (28-41%); P= 0.01). These data indicate that bone marrow transplants from HLA-identical siblings result in comparable survival but greater LFS than chemotherapy in adults with AML in first remission.

A total of 1634 recipients of HLA-identical sibling bone marrow with acute leukemia were treated with the combination of cyclosporin A (CsA) and methotrexate as prophylaxis against graft-versus-host disease (GVHD). The probability of relapse decreased with an increasing grade of acute GVHD, especially in patients grafted in first remission (CR-1): P0.01 and P0.001 for acute lymphoblastic leukemia and acute myeloid leukemia, respectively. Among patients surviving at least 3 months without a relapse, chronic GVHD was associated with a decreased incidence of relapse in CR-1 (P0.0001 for both diagnoses), and a better LFS. Among patients in CR-1, the probability of relapse was the same in those with limited or with extensive chronic GVHD. However, in patients with intermediate stage of the disease (or = 2nd remission or 1st relapse) with previous acute GVHD, those with extensive chronic GVHD had a reduced probability of relapse (P = 0.05). The graft-versus-leukemia effect of acute and especially chronic GVHD was confirmed by multivariate analyses. Overall, the highest LFS was seen in patients with chronic GVHD and no or grades I-II acute GVHD. The lowest LFS was seen in patients having acute GVHD grades III-IV without chronic GVHD.

Human cord and placental blood provides a rich source of hematopoietic stem cells. On the basis of this finding, umbilical cord blood stem cells have been used to reconstitute hematopoiesis in children with malignant and non malignant diseases after treatment with myeloablative doses of chemoradiotherapy. Early results show, that a single cord blood provides enough hematopoietic stem cells to provide short and long term engraftment and, that the incidence and severity of graft versus host disease has been low even in HLA mismatched transplants. This results are encouraging enough, to embark on large scale banking of cord blood for purposes of future allogeneic and autologous stem cell transplantation, to promote studies on the unique properties of fetal and neonatal hematopoiesis, to study the immunological properties of cord blood cells and, to initiate investigations on gene transfer into human cord blood cells for future gene therapy trials. This review will briefly summarize the current knowledge on cord blood transplantation as well as the future development of research on this unique source of hematopoietic stem cells. Clinical results of cord blood transplantation.

We report two patients treated with interferon-alpha who developed Raynaud's phenomenon followed by multiple digital necrosis. Arteriography of the legs revealed diffuse distal narrowing. Histological examination of the resected tissue showed ischaemic necrosis within the dermis and subcutaneous tissue without vasculitis. Resolution of the symptoms was observed when interferon-alpha was withdrawn. Since other causes of Raynaud's phenomenon and digital necrosis were ruled out, a drug cause is likely. Raynaud's phenomenon should be looked for in patients treated with interferon-alpha. If present, immediate withdrawal of the drug is required.

Paroxysmal nocturnal haemoglobinuria (PNH) is a rare acquired disorder of haematopoietic stem cells. Although knowledge about the pathophysiology of the disease is increasing, no multivariate analysis of factors influencing survival has been undertaken, mainly because the disease is rare. We undertook such an investigation.Data were collected on 220 patients with PNH diagnosed over a 46-year period (1950-1995) from participating French centres. Diagnosis of the disease required, at least, an unequivocally positive Ham's test.The Kaplan-Meier survival estimate was 65% (SE 4) at 10 years and 48% (6) at 15 years after diagnosis. 8-year cumulative incidence rates of the main complications (pancytopenia, thrombosis, and myelodysplastic syndrome) were 15% (3), 28% (4), and 5% (2), respectively. Demographic data, presenting features, initial treatment, complications, and causes of death were similar to those previously reported. In multivariate analysis, seven factors were significantly associated with survival in patients with PNH. Poor survival was associated with the occurrence of thrombosis as a complication (relative risk 10.2 [95% CI 6-17], p0.0001), evolution to pancytopenia (5.5 [2.8-11], p0.0001), myelodysplastic syndrome or acute leukaemia (19.1 [7.3-50], p0.001), age over 55 years at diagnosis (4 [2.4-6.9], p0.0001), need for additional treatment (2.1 [1.3-3.6], p0.003), and thrombocytopenia at diagnosis (2.2 [1.3-3.8, p0.003). Better survival was shown for patients in whom aplastic anaemia antedated PNH (0.32 [0.14-0.72], p0.02). Factors associated in multivariate analysis with a high risk of thrombosis during the disease course were thrombosis at diagnosis (5.1 [2.5-10.6], p = 0.0002), age over 54 years (2.6 [1.5-4.6, p = 0.0014), and infection at diagnosis (2.6 [1.3-5.2], p = 0.0099). The risk factors for progression to pancytopenia were absence at diagnosis of anaemia (4.03 [1.3-12.2], p = 0.03) and neutropenia (2.45 [1.1-5.7], p = 0.03). The risk factors for development of myelodysplastic syndrome or acute leukaemia were abdominal pain crisis at presentation (10.5 [2.5-44.0], p = 0.004) and year of diagnosis after 1983 (8.45 [1.8-40.7], p = 0.004).This large number of cases permitted a detailed analysis of prognostic factors for the first time, in this rare disease. Estimates of PNH prognostic factors may serve as baseline data in the assessment of current and future treatments for this disease.

We investigated in 15 consecutive patients a possible correlation between expression of CMV or EBV in labial salivary gland (LSG) biopsies performed 100 days after allogeneic BMT and subsequent development of chronic GVHD. Three techniques were performed for the detection of each virus: immunohistochemistry, in situ hybridization and PCR. Eleven patients developed chronic GVHD. Histologic examination detected a moderate lymphoid infiltrate (grade 1 according to Sale's score) in LSG biopsy in only one patient. CMV genes or proteins could not be detected in any patients. Likewise, EBV genome or proteins were not detected by in situ hybridization and immunohistochemistry. However, in three of the 15 patients, EBV DNA was detected by PCR in LSG biopsies. Only one of these three patients developed chronic GVHD. Therefore, at the present time, the presence of a lymphoid infiltrate on lip biopsies performed at day 100 post-BMT does not appear to be sensitive enough for the diagnosis or the prediction of the subsequent development of chronic GVHD. Moreover, the absence of EBV and CMV expression in a day-100 LSG biopsy does not preclude the development of chronic GVHD.

To evaluate whether the results of bone marrow transplantation have improved in Europe with time, we analyzed the outcome for 2195 patients with acute leukemia. 1405 had acute myeloid leukemia (AML) and 790 had acute lymphoblastic leukemia (ALL), and were allografted in first complete remission between September 1979 and December 1991 with marrow from an HLA-identical sibling donor. We found a continuing improvement more evident since 1987 for AML and since 1986 for ALL. A substantial reduction in the 3 years transplant related mortality (TRM): 26 vs 39% for AML (P = 10(-4)), and 25 vs 39% for ALL (P = 10(-4)), has resulted in an increase of the 5-year actuarial leukemia-free survival (LFS). 57 vs 45% for AML (P10(-4)) and 54 vs 45% (P = 10(-4)) for ALL. Four important changes have occurred. (1) Graft-versus-host disease (GVHD) prevention has involved an increased use of cyclosporin A (CsA) alone and subsequently its use in combination with methotrexate: this was associated with lower TRM both in AML and ALL; (2) Use of total body irradiation as pretransplant regimen has decreased; (3) a shorter interval from remission to BMT is more common; (4) an older population of patients has undergone BMT. Multivariate analyses were performed separately in AML and ALL. In AML four variables significantly influenced TRM favorably: year of BMT (P = 10(-4)), younger age at BMT (P = 10(-4)), prevention of GVHD including CsA (P = 0.008), sex match other than female donor to male recipient (P = 0.002). The relapse incidence (RI) was lower in patients with FAB M1-2-3 vs M4-5 (P = 0.0004). The LFS improved by year of BMT (P = 0.0004), younger age at BMT (P = 10(-4)), prevention of GVHD including CsA (P = 0.01), FAB M1-2-3 (P = 0.03). In ALL, three variables were associated with a lower TRM: year of BMT (P = 10(-4)), younger age at BMT (P = 10(-4)), sex combination other than female to male (P = 0.008). The LFS was better after 1986 (P = 0.0004) and in younger patients (P = 10(-4)). However a better outcome after 1986/87 was observed in patients receiving the same GVHD prophylaxis: therefore, other unidentified factors resulting in better patient care have also contributed to this. The improved results of allogeneic BMT are entirely related to a reduction in TRM without loss of the antileukemic effect since relapse incidence has not changed over the years.

Risk factors for the development of a new (secondary) malignancy after marrow transplantation are still incompletely defined. In the present study, we analyzed results in 700 patients with severe aplastic anemia treated with allogeneic marrow transplantation at the Fred Hutchinson Cancer Research Center in Seattle, WA, or at the Hôpital St Louis in Paris, France. Twenty-three patients developed a malignancy 1.4 to 221 months (median, 91 months) after transplantation for a Kaplan-Meier estimate of 14% (95% confidence interval, 4% to 24%) at 20 years. Five cases were lymphoid malignancies (two acute lymphoblastic leukemias and three lymphoproliferative disorders) occurring 1.4 to 14.6 months (median, 3 months) posttransplant, and 18 were solid tumors (17 squamous cell and one mucoepidermoid carcinoma) presenting 30 to 221 months (median, 99 months) posttransplant. Thus, the hazard for lymphoid malignancies declined rapidly posttransplant, while the hazard for solid tumors increased progressively with time posttransplant. Risk factors for solid tumors identified in univariable analysis included the underlying diagnosis of Fanconi anemia (P = .0002), azathioprine therapy for chronic graft-versus-host disease (GVHD) (P.0001), irradiation (total body or thoracoabdominal) as part of the conditioning regimen (P = .0002), chronic GVHD (P = .0099), acute GVHD (P = .0135), and male sex (P = .0499). In multivariable, stepwise proportional hazards models, azathioprine therapy (P.0001) and the diagnosis of Fanconi anemia (P.0001) were significant factors for all patients. Irradiation was a significant factor (P = .004) only if the time-dependent variable azathioprine was not included in the analysis. If only non-Fanconi patients were considered, azathioprine (P = .0043), age (P = .025), and irradiation (P = .042) were significant factors. Results in patients with Fanconi anemia and malignancies other than solid tumors were not subjected to an analysis because of the small number of events. It is of note, however, that no case of myeloproliferative disorder was observed. In summary, the highest risk of developing a solid tumor was associated with the diagnosis of Fanconi anemia. Better prevention of GVHD or omission of azathioprine as GVHD therapy (or both) may reduce the risk of late tumor development. Similarly, nonirradiation conditioning regimens may reduce the tumor risk, at least in patients without Fanconi anemia. Interactions between potential risk factors are complex, and further observation and additional analyses will be of interest.

Umbilical cord blood is considered an alternate source of hematopoietic stem cells in bone marrow transplantation. However, its use might be hampered by contamination of neonatal blood with maternal cells, which could contribute unacceptably to graft-vs.-host disease (GVHD) after transplant. In a previous study (Socié et al., Blood 83:340, 1994), we used polymerase chain reaction (PCR) amplification of minisatellite sequences (sensitivity 1-0.1%) to address the question of this contamination. In a single case among 47 analyzed, we were able to detect a maternal-specific allele in the cord blood sample. We have now studied the same cord samples using a highly sensitive, allele-specific PCR amplification method. A maternal allele could be discriminated from neonate alleles in 10 cases and maternal cells were detected in all 10 cord blood samples. These cells amounted to 10(-4) to 10(-5) of cord blood nucleated cells. In three cases, cord blood separated cell subpopulations could be analyzed and were found to contain maternal cells at about the same level. The presence of maternal cells at such a low level in cord blood samples probably would have no effect on GVHD in a clinical setting of transplantation but raises interesting questions in terms of materno-fetal immune tolerance and transmission of viruses (in particular human immunodeficiency virus) from infected mother to child.