Cotransplantation of ex vivo expanded mesenchymal stem cells accelerates lymphocyte recovery and may reduce the risk of graft failure in haploidentical hematopoietic stem-cell transplantation

Haploidentical hematopoietic stem-cell transplantation (HSCT) is associated with an increased risk of graft failure. Adult bone marrow-derived mesenchymal stromal cells (MSCs) have been shown to support in vivo normal hematopoiesis and to display potent immune suppressive effects. We cotransplanted donor MSCs in 14 children undergoing transplantation of HLA-disparate CD34(+) cells from a relative. While we observed a graft failure rate of 15% in 47 historic controls, all patients given MSCs showed sustained hematopoietic engraftment without any adverse reaction. In particular, children given MSCs did not experience more infections compared with controls. These data suggest that MSCs, possibly thanks to their potent immunosuppressive effect on alloreactive host T lymphocytes escaping the preparative regimen, reduce the risk of graft failure in haploidentical HSC transplant recipients.

Differences in telomerase expression by the CD1a+ cells in Langerhans cell histiocytosis reflect the diverse clinical presentation of the disease

Langerhans cell histiocytosis (LCH) is a disease characterized by an uncontrolled clonal proliferation of Langerhans cells, whose aetiology is still unclear. The clonal nature of LCH could support the hypothesis that it is a neoplastic disease with unlimited growth potential. One requirement for unlimited proliferation is the maintenance of telomere length. In a group of 70 patients, we set out to investigate whether a telomere maintenance mechanism is indeed active in LCH cells. This work showed that LCH cells from all restricted skin LCH lesions (6/6) expressed telomerase as assessed by human telomere reverse transcriptase (hTERT) immunohistochemistry, whereas LCH cells from the majority of the bone lesions analysed did not express hTERT (26/34). Interestingly, in contrast to the solitary bone lesions, LCH cells from lesions of multi-system patients always expressed telomerase (11/11), regardless of the lesional site. In situ telomeric repeat amplification protocol (TRAP) assays performed on different lesional sites showed that this telomerase was active. In addition, the telomere length of LCH cells from a hTERT-positive skin multi-system lesion was long and homogeneous when compared to that in the LCH cells from hTERT-negative bone single-system LCH lesions, which was heterogeneous in length. No evidence for an alternative lengthening of telomeres mechanism was found in hTERT-negative lesions. The difference in telomerase expression and telomere length at the different lesional sites and in biopsies from patients with solitary versus multi-system disease appears to reflect the diverse clinical presentation and course of this disease. The results from this study have important implications for understanding the nature of this disease.

HLA-identical haematopoietic stem cell transplantation for acute leukaemia in children: less relapse with higher biologically effective dose of TBI

To examine relapse, survival and transplant-related complications in relationship to disease- and pre-treatment-related characteristics, we evaluated 132 children, who consecutively received an allogeneic HLA-identical SCT for acute leukaemia in our centre: ALL in first remission (n=24), ALL in second remission (n=53) and AML in first remission (n=55). The source of the stem cells was bone marrow in all but three cases. Most patients (89%) were pre-treated with cyclophosphamide and an age-related dose of TBI. Initially, GVHD prophylaxis consisted of long-course MTX only (n=24), later short-course MTX and CsA (n=102) was given. All patients were nursed in strictly protective isolation and received total gut decontamination to suppress their potentially pathogenic enteric microflora. The 5-year probability of overall survival was 63, 53 and 74% for ALL1, ALL2 and AML1, respectively (median follow-up: 10.6 years). The overall transplant-related mortality was 6%. The incidence of acute GVHD was 17%; 6% was grades II-IV. A higher total biologically effective TBI dose (BED) resulted in a decreased relapse frequency (P=0.034) and increased overall survival. AML patients with acute GVHD got no relapse (P=0.02); this was not the case in ALL patients. Fractionated TBI regimens with higher BED should be evaluated in prospective studies.

HLH-2004: Diagnostic and therapeutic guidelines for hemophagocytic lymphohistiocytosis

In HLH-94, the first prospective international treatment study for hemophagocytic lymphohistiocytosis (HLH), diagnosis was based on five criteria (fever, splenomegaly, bicytopenia, hypertriglyceridemia and/or hypofibrinogenemia, and hemophagocytosis). In HLH-2004 three additional criteria are introduced; low/absent NK-cell-activity, hyperferritinemia, and high-soluble interleukin-2-receptor levels. Altogether five of these eight criteria must be fulfilled, unless family history or molecular diagnosis is consistent with HLH. HLH-2004 chemo-immunotherapy includes etoposide, dexamethasone, cyclosporine A upfront and, in selected patients, intrathecal therapy with methotrexate and corticosteroids. Subsequent hematopoietic stem cell transplantation (HSCT) is recommended for patients with familial disease or molecular diagnosis, and patients with severe and persistent, or reactivated, disease. In order to hopefully further improve diagnosis, therapy and biological understanding, participation in HLH studies is encouraged.

Haematopoietic stem cell transplantation trends in children over the last three decades: a survey by the paediatric diseases working party of the European Group for Blood and Marrow Transplantation

This paper describes the trends in haematopoietic stem cell transplantation (HSCT) activity for children in Europe over the last three decades. We analysed 31,713 consecutive paediatric HSCTs reported by the European Group for Blood and Marrow Transplantation (EBMT) centres between 1970 and 2002. Data were taken from the EBMT registry and were compared according to period and centre category (paediatric or combined). Since 1996, there has been a significant increase in the number of HSCTs performed exclusively by paediatric centres, as well as in the number of alternative donor HSCTs, and in the use of peripheral blood stem cells (P<0.0001). The number of allogeneic HSCTs (allo-HSCTs) for acute lymphoblastic leukaemia, acute myeloblastic leukaemia and chronic myeloid leukaemia remained stable, whereas it increased for myelodysplastic syndromes and lymphomas, and decreased significantly for non-malignant diseases (P<0.0001). Multivariate analysis showed that younger age, human leukocyte antigen genoidentical donors, HSCT performed after 1996 and transplant centres performing more than 10 allo-HSCT/year were all associated with decreased transplant-related mortality (TRM) (P<0.0001). The number of autologus HSCTs (auto-HSCTs) for acute leukaemia decreased significantly, whereas it increased for solid tumours (P<0.0001). Multivariate analysis showed that both auto-HSCT performed before 1996 and paediatric solid tumours (P<0.0001) had higher TRM. Indications for paediatric HSCT have changed considerably during the last seven years. These changes provide tools for decision making in health-care planning and counselling.

Expression of Cellular FLICE Inhibitory Protein, Caspase-8, and Protease Inhibitor-9 in Ewing Sarcoma and Implications for Susceptibility to Cytotoxic Pathways

PURPOSE

Ewing sarcoma is a common pediatric bone tumor with an unfavorable prognosis for metastatic or recurrent disease. Cellular immunotherapy may provide new treatment options and depends on the cytolytic death receptor and perforin/granzyme pathways. Expression of death receptor pathway inhibitor cellular FLICE inhibitory protein (cFLIP), initiator caspase-8, and granzyme B inhibitor protease inhibitor-9 (PI-9) have been reported to determine susceptibility to cell- and chemotherapy-mediated killing in several tumor types. Here, we have studied their in vitro and in vivo expression in Ewing sarcoma and the implications for susceptibility to cytotoxicity.

EXPERIMENTAL DESIGN

Ewing sarcoma cell lines (n = 8) were tested for cFLIP, PI-9, and caspase-8 expression. Functional significance was tested by anti-Fas antibody (death receptor pathway) or natural killer cell (perforin/granzyme pathway) treatment. Immunohistochemistry was done on 28 sections from 18 patients. In half of the cases, sequential material, including metastases, was available.

RESULTS

Although all tested Ewing sarcoma cell lines expressed cFLIP, resistance to CD95/Fas-mediated apoptosis was only observed in two cell lines lacking caspase-8 expression. PI-9 was expressed at low levels in four of eight Ewing sarcoma cell lines, but positive cell lines remained susceptible to perforin/granzyme-mediated killing. In primary Ewing sarcoma, including metastases, cFLIP was abundantly expressed in 18 of 18 patients. Caspase-8 was expressed in all patients but showed more intertumoral and intratumoral variation in both intensity and heterogeneity of staining. PI-9, in contrast, was undetectable.

CONCLUSIONS

The expression patterns of cFLIP, caspase-8, and the absence of PI-9 provide a rationale to preferentially exploit the perforin/granzyme pathway in cytotoxic therapies against Ewing sarcoma.

Once-daily intravenous busulfan in children prior to stem cell transplantation: study of pharmacokinetics and early clinical outcomes

We studied the pharmacokinetics and clinical outcome of a new once-daily intravenous area under the curve-targeted dosing scheme for busulfan based on body surface area. Eighteen children undergoing busulfan-based conditioning for allogeneic stem cell transplantation were enrolled. The age of the children ranged from 0.5 to 16 years. For all children, the starting dose was 80 mg/m. Unlimited dose adjustment was allowed to reach the target area under the curve (3800 micromol/l . min). This target area under the curve was determined on the basis of a previous study in our hospital. Pharmacokinetic studies were performed after the first dose. The median area under the curve on day 1 was 2616 (range 1781-5040) micromol/l . min at a dose of 80 mg/m. This resulted in a median dose increment to 114 (range 62-168) mg/m to reach the target area under the curve. In only one patient, the dose was decreased. Donor engraftment was established in 14 out of 18 patients (78%). Two of the four patients were successfully retransplanted. Relapse occurred in two patients (one died, one received additional treatment). Fourteen patients survived with a median follow-up of 1.6 years (1.0-2.2 years). The disease-free survival was 66% (12 of 18 patients). Despite the high systemic peak levels, there was no new unexpected or unusual toxicity. Moderate veno-occlusive disease was seen in one patient only. We conclude that intravenous busulfan in children administered once daily is safe, convenient and feasible, and can be dosed surface-based, independent of age. There was very limited (liver) toxicity, but the rejection rate was relative high, which can be probably overcome by a higher exposure to busulfan. Future investigations should be aimed at further optimizing the target area under the curve of intravenous busulfan for specific patient groups.

A possible role for CCL27/CTACK-CCR10 interaction in recruiting CD4 T cells to skin in human graft-versus-host disease

Graft-versus-host disease (GvHD) is a serious complication of allogeneic stem cell transplantation (SCT) affecting the skin, gut and liver. The involvement of distinct organs suggests a role for tissue-specific chemokines and their receptors in directing activated donor T cells to these sites. In this study the potential involvement of the skin-specific CCL27/CTACK-CCR10 interaction was investigated in 15 paediatric SCT patients with skin GvHD. During the course of skin GvHD, peripheral blood T cells from these patients contained a high proportion of CD4+ CCR10+ T cells that disappeared after the GvHD was resolved. These cells were CD45RO+, expressed additional skin homing markers (cutaneous lymphocyte-associated antigen and CCR4), and produced the T-cell helper type 1-cytokines tumour necrosis factor-alpha and interleukin-2. The increase in CD4+ CCR10+ T cells was absent in SCT patients without GvHD. Immunohistochemical investigations showed CD4+ CCR10+ T cells in the GvHD skin biopsies of the same patients, but not in the gut biopsies of patients also suffering from gut GvHD. The infiltration of CD4+ CCR10+ T cells in the GvHD-affected skin correlated with an enhanced epidermal expression of CCL27/CTACK, the ligand for CCR10. These findings support the involvement of CCL27/CTACK-CCR10 interaction in recruiting CD4+ T cells to the skin, thus contributing to the pathogenesis of acute GvHD.

Management of Epstein-Barr Virus (EBV) Reactivation after Allogeneic Stem Cell Transplantation by Simultaneous Analysis of EBV DNA Load and EBV-Specific T Cell Reconstitution

BACKGROUND

Epstein-Barr virus (EBV) reactivation is a frequent event after allogeneic stem cell transplantation and may progress to life-threatening lymphoproliferative disease (EBV-LPD) in the absence of adequate EBV-specific T cell immunity. Quantification of EBV DNA load in asymptomatic individuals who are at risk is a useful (although not entirely predictive) indicator of progression to EBV-LPD and guide for preemptive treatment with CD20 antibodies.

METHODS

With the aim of improving the identification of patients at risk, we retrospectively analyzed, within a cohort of 25 consecutive allogeneic stem cell transplant recipients at risk for EBV-LPD, the pattern of T cell reconstitution during EBV reactivation in all preemptively treated patients (8 patients).

RESULTS

In 6 of 8 cases, a significant T cell reconstitution (i.e., a CD3+ T cell count of >300 cells/microL) was documented during EBV reactivation, which included an expansion of EBV-specific memory T cells, as shown by human leukocyte antigen class I tetramer analysis. Additional evidence for the antiviral potential of this T cell reconstitution was obtained prospectively from a cohort of 14 consecutive allogeneic stem cell transplant recipients at risk for EBV-LPD. EBV reactivation occurred in 3 patients. Preemptive treatment was successfully withheld for 2 of these patients in light of concurrent (EBV-specific) T cell recovery.

CONCLUSION

We conclude that analysis of the level of (EBV-specific) T cell reconstitution during EBV reactivation is an important second parameter, in addition to quantification of EBV DNA load, that will be instrumental in a more accurate definition of patients at risk for EBV-LPD who, given their immunoincompetence, will be most certainly dependent on preemptive interventions.

Biology of Langerhans cells and Langerhans cell histiocytosis

Langerhans cells (LC) are epidermal dendritic cells (DC). They play an important role in the initiation of immune responses through antigen uptake, processing, and presentation to T cells. Langerhans cell histiocytosis (LCH) is a rare disease in which accumulation of cells with LC characteristics (LCH cells) occur. LCH lesions are further characterized by the presence of other cell types, such as T cells, multinucleated giant cells (MGC), macrophages (MPhi), eosinophils, stromal cells, and natural killer cells (NK cells). Much has been learned about the pathophysiology of LCH by studying properties of these different cells and their interaction with each other through cytokines/chemokines. In this review we discuss the properties and interactions of the different cells involved in LCH pathophysiology with the hope of better understanding this enigmatic disorder.

Health-related quality of life and coping strategies of children after treatment of a malignant bone tumor: a 5-year follow-up study

PURPOSE

This study was designed to evaluate the development of health-related quality of life (HRQoL) and coping strategies of children and young adults, who have undergone surgery for a malignant bone tumor in childhood. PATIENTS AND INSTRUMENTS: In this single center follow-up study 20 patients were included. The patients were tested 3 and 8 years after treatment. At the 3-year mark the parents participated as well. To measure the HRQoL and coping strategies the TACQOL and the TAAQOL questionnaires and the Utrecht Coping List for Adolescents (UCLA) were used. All measurements were compared to a control group of healthy peers (n = 1,122 and n = 272, respectively).

RESULTS

At the first measurement (3 years after treatment) both the study patients and their parents reported significantly lower HRQoL scores on two domains: motor functioning and autonomy (P < 0.05). In addition parents reported their children to have significantly lower HRQoL scores on cognitive functioning and experiencing positive emotions. Five years later (8 years after treatment) the young adults reported comparable HRQoL on motor functioning and autonomy, and significantly higher HRQoL scores on cognitive functioning, social contacts and negative emotions (less depressive moods). With regard to coping strategies no significant differences between the two measurements in the study population and the reference group were found.

CONCLUSIONS

Three years after surgery for a malignant bone tumor, patients and their parents reported lower HRQoL scores on different domains compared with a reference group. Eight years after surgery the young adults surprisingly reported comparable or higher HRQoL scores. These patients treated for bone cancer were able to adapt well after treatment and showed no long-term emotional or social problems.

Allogeneic stem cell transplantation in X-linked lymphoproliferative disease: two cases in one family and review of the literature

X-linked lymphoproliferative disease (XLP) is a rare immunodeficiency caused by mutations in the signaling lymphocyte activating molecule-associated protein/SH2D1A gene and characterized by a dysregulated immune response to Epstein-Barr virus and other pathogens. The clinical presentation is heterogeneous and includes fulminant infectious mononucleosis, lymphoma, hypogammaglobulinemia and aplastic anemia. XLP is associated with a high morbidity and overall outcome is poor. At present, allogeneic stem cell transplantation (alloSCT) is the only curative treatment. XLP patients may be recognized in various stages of disease and even when symptoms are not yet evident. We here present two related XLP patients in different stages of disease that were both treated successfully with alloSCT using a matched unrelated donor. In addition, we have reviewed all reported cases of alloSCTs in XLP patients. Based on these results and in order to improve the final outcome, we conclude that alloSCT should be recommended in both symptomatic and asymptomatic XLP patients.

Haematopoietic stem cell transplantation in haemophagocytic lymphohistiocytosis

Haemophagocytic lymphohistiocytosis (HLH) poses major therapeutic challenges, and the primary inherited form, familial haemophagocytic lymphohistiocytosis (FHL), is usually fatal. We evaluated, including Cox regression analysis, survival in 86 children (29 familial) that received HLH-94-therapy (etoposide, dexamethasone, ciclosporin) followed by allogeneic stem cell transplantation (SCT) between 1995 and 2000. The overall estimated 3-year-survival post-SCT was 64% [confidence interval (CI) = +/-10%] (n = 86); 71 +/- 18% in those patients with a matched related donor (MRD, n = 24), 70 +/- 16% with a matched unrelated donor (MUD, n = 33), 50 +/- 24% with a family haploidentical donor (haploidentical, n = 16), and 54 +/- 27% with a mismatched unrelated donor (MMUD, n = 13). After adjustment for potential confounding factors, estimated odds ratios (OR) for mortality were 1.93 (CI =0.61-6.19) for MUD, 3.31 (1.02-10.76) for haploidentical, and 3.01 (0.91-9.97) for MMUD, compared with MRD. In children with active disease after 2-months of therapy (n = 43) the OR was 2.75 (1.26-5.99), compared with inactive disease (n = 43). In children with active disease at SCT (n = 37), the OR was 1.80 (0.80-4.06) compared with inactive disease (n = 49), after adjustment for disease activity at 2-months. Mortality was predominantly transplant-related. Most HLH patients survived SCT using MRD or MUD, and survival with partially mismatched donors was also acceptable. Patients that responded well to initial pretransplant-induction therapy fared best, but some persisting HLH activity should not automatically preclude performing SCT.

Allogeneic bone marrow transplantation for juvenile myelomonocytic leukemia: a single center experience of 23 patients

Juvenile myelomonocytic leukemia (JMML) is a childhood leukemia for which allogeneic BMT is the only curative therapy. At our pediatric stem cell transplantation unit, we performed 26 BMTs in 23 children (age 0.5–12.7 years). Conditioning was CY/TBI based (1980–1996, n=14) or BU/CY/melphalan based (1996–2001, n=9). Donors were HLA-identical siblings (n=11), unrelated volunteers (n=9) or mismatched family members (n=3). A total of 10 patients survive in CR (median follow-up 6.8 years, range 3.1–22.2 years). Relapse or persistent disease was observed in eight and two patients, respectively. Nine of these patients died, one achieved a second remission following acute nonlymphatic leukemia chemotherapy (duration to date 5.3 years). Transplant-related mortality occurred in four patients. Overall survival at 5 and 10 years was 43.5%. Using T-cell-depleted, one-antigen mismatched unrelated donors was the only significant adverse factor associated with relapse in multivariate analysis (P=0.039, hazard ratio 4.9). Together with a trend towards less relapse in patients with graft-versus-host-disease and in patients transplanted with matched unrelated donors, this suggests a graft-versus-leukemia effect of allogeneic BMT in JMML.

The Nikolas Symposia and histiocytosis

Histiocytoses are a group of rare diseases that involve histiocytes (literally tissue cells (Greek), but in reality tissue-resident macrophages and dendritic cells), which are derived from bone-marrow stem cells. Histiocytoses pose problems similar to those of other rare diseases of childhood. Individual physicians see few cases, disease material is hard to collect and families suffer from lack of information and understanding. In this article, we describe how a series of 'think tank' meetings, the Nikolas Symposia, which have concentrated on Langerhans cell histiocytosis, have furthered our understanding of this enigmatic disease.

Causes of death--other than progressive leukemia--in childhood acute lymphoblastic (ALL) and myeloid leukemia (AML): the Dutch Childhood Oncology Group experience

We analyzed causes of death, other than resistant disease or relapse, in 875 children with acute lymphoblastic leukemia (ALL) and 229 with acute myeloid leukemia (AML), treated on three different Dutch Childhood Oncology Group (DCOG) ALL and three AML protocols. Overall, 23 (2.6%) ALL and 44 (19.2%) AML patients died. Early death (ED, before remission was reached) occurred in nine ALL (1%) and thirty AML (13.1%) patients, including three and ten deaths before treatment was initiated. Chemotherapy-related mortality in remission (CRM) occurred in nine ALL (1.1%) and eight AML (4.4%) patients. For ALL, both ED and CRM declined over time, although this was not statistically significant. For AML a decrease in ED was observed (from 26% to approximately 10%), but counter-balanced by an increase in CRM (from 3 to 8%), maybe related to the scheduling of intensification blocks in AML-92/94. Including transplant-related mortality, death in CR rates in AML increased from 3 to 15% in the last study. The main cause of ED was hemorrhage, often associated with hyperleucocytosis, and infection for CRM. We conclude that mortality dropped favorably in ALL, but not in AML. Especially for AML, effective but less toxic therapy and better supportive care guidelines need to be developed.

Intravenous busulfan in children prior to stem cell transplantation: study of pharmacokinetics in association with early clinical outcome and toxicity

We studied the pharmacokinetics of intravenous busulfan (Bu) in children in order to further optimize intravenous Bu dosing in relation to toxicity and survival. A total of 31 children undergoing Bu-based conditioning for allogeneic SCT were enrolled in a study. The starting dose was 1.0 mg/kg (age < 4 years) and 0.8 mg/kg (age > or =4 years), four doses per day during 4 days. Dose adjustment was allowed up to a maximum dose of 1.0 mg/kg per dose if the target area under the serum concentration-time curve (AUC) was not reached. Pharmacokinetic studies were performed after the first dose. Donor engraftment was established in 28 out of 31 patients. The average AUC after the first dose was the same in children < 4 years as in children > or =4 years. Mean clearance was higher in children < 4 years than in children > or =4 years. In 35% of all patients, total AUC was within the target AUC. The other children's AUCs were below the target range. No relationships were found between systemic exposure to Bu and toxicity or clinical outcome. We concluded that, in accordance with previous data, within the observed AUCs no clear relationship was observed between Bu AUC and outcome with respect to toxicity, engraftment and relapse.

Graft dysfunction and delayed immune reconstitution following haploidentical peripheral blood hematopoietic stem cell transplantation

For many children with life-threatening hematological diseases, hematopoietic stem cell transplantation (HSCT) is the only curative option. In children lacking a matched related or unrelated donor and with the certainty that, left untreated, death will ensue alternative donors must be sought. Haplo-identical peripheral blood stem cell transplantation (PBSCT) from a healthy parent is a feasible alternative. To reduce the risk of fatal graft-versus-host disease (GvHD) as a complication of transplant across major histocompatibility antigens, intense T-cell depletion is required. Large numbers of purified, cytokine mobilized peripheral stem cells (the so-called mega-dose concept) are required to compensate for the significantly increased risk of either graft failure or early rejection. In our unit, despite this approach, graft dysfunction has, in a significant group of children, proved problematic and, despite salvage attempts at re-transplantation, usually fatal. In children with hematological malignant disease, our overall relapse-free survival is 41%. However, successful transplant outcome has been associated with considerable delays in immune reconstitution that can be implicated in subsequent viral reactivation. We are investigating new strategies to improve the outcome of haplo-identical PBSCT, which may allow us to offer this form of treatment to more children requiring urgent HSCT.

Adenovirus infection in children after allogeneic stem cell transplantation: diagnosis, treatment and immunity

Human adenoviruses (HAdV) are a frequent cause of potentially fatal infections in patients after allogeneic stem cell transplantation, especially in children. Monitoring of serum/plasma by real-time quantitative PCR is a sensitive tool for the recognition of patients at risk of a potentially fatal infection and for the evaluation of the efficacy of treatment. Data from a retrospective study and from a prospective study demonstrate that recovery of immunity after transplantation is essential for the elimination of HAdV infection. The feasibility of several approaches for the manipulation of immunity in the immunocompromised host to prevent a fatal course of the infection is discussed.

Survey on haematopoietic stem cell transplantation for children in Europe

A recent report, prepared in March 2003, regarding the paediatric transplantation activity registered between 1970 and 2002 in the European Bone Marrow Transplantation (EBMT) database showed a decrease in the number of registrations in 2001 and in 2002. In order to validate this observation, the Paediatric Diseases Working Party (PDsWP) secretariat distributed a questionnaire to 395 institutions participating in the EBMT Registry. Each institution was requested to check the number of transplants they reported and to confirm or to correct the figures. As of 15 March 2004, replies had been received from 135 centres reporting a median of 48 transplants per centre over the study period, total 17 891 (58% of the total number). Among them, 55 confirmed their original figures, while 80 corrected the numbers. The overall number of autologous and allogeneic SCTs performed and not reported were 461 and 692, respectively. Most of the teams that corrected their figures stated that their data managers could provide missing data to the EBMT; 260 other teams, each reporting a median of 15 transplants during the study period, total 12 866 (42% of the total number) chose not to reply. A report prepared in March 2004, following the PDsWP survey, showed an increasing number of transplants performed on patients below 18 years of age between 1973 and 2002 and reported to the EBMT Registry (328 autologous and 628 allogeneic) as compared to the 2003 report. This first PDsWP survey, reaching more than 50% of activity in the field, illustrates that the decrease in activity we observed in the 2003 report does not correspond to a decrease in the number of transplants that were actually performed. It demonstrates the compliance of most major paediatric institutions and confirms the important role of cooperation between National Registries and EBMT Registries.

Presence of osteoclast-like multinucleated giant cells in the bone and nonostotic lesions of Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a disease that can involve one or multiple organ systems characterized by an accumulation of CD1a(+) Langerhans-like cells as well as several other myeloid cell types. The precise origin and role of one of these populations, the multinucleated giant cell (MGC), in this disease remains unknown. This work shows that in three different lesional tissues, bone, skin, and lymph node, the MGCs expressed the characteristic osteoclast markers, tartrate-resistant acid phosphatase and vitronectin receptor, as well as the enzymes cathepsin K and matrix metalloproteinase-9. Although, in bone lesions, the osteoclast-like MGCs were only CD68(+), in the nonostotic sites, they coexpressed CD1a. The presence of osteoclast-like MGCs may be explained by the production of osteoclast-inducing cytokines such as receptor activator of nuclear factor kappaB ligand and macrophage colony-stimulating factor by both the CD1a(+) LCH cells and T cells in these lesions. As osteoclast-derived enzymes play a major role in tissue destruction, the osteoclast-like nature of MGCs in all LCH lesions makes them a potential target for the treatment of this disease.

How to improve the search for an unrelated haematopoietic stem cell donor. Faster is better than more!

Many patients do not reach haematopoietic stem cell transplantation. Shortage of unrelated donors (UDs) is still seen as the main cause. However, with a worldwide UD pool containing more than 8 million donors, it is possible that other impediments are becoming more important. We analysed 549 UD searches for Dutch patients, performed between 1987 and 2000, in order to find the reasons for failure or success to reach transplantation. Between 1996 and 2000, 59% of the patients of Northwest European origin received a graft from an UD with a median time span of 4.4 months from the start of the search. In all, 11% of the patients lacked a compatible donor, while 30% became medically unfit for transplantation. This is in contrast to the patients of non-Northwest European origin for whom UD shortage is still the most important impediment; only 32% were transplanted while 50% lacked a compatible donor. We conclude that the shortage of donors is no longer the biggest constraint in unrelated stem cell transplantation for patients of Northwest European origin. It may be more effective to optimize the chance on transplantation by making the search process more efficient.

The importance of identifying a back-up donor for unrelated stem cell transplantation

The importance of identifying a back-up donor, once a primary suitable unrelated stem cell donor has been found, is often underestimated. Transplant centres erroneously count on the unrelated volunteer donors to be willing, available and medically fit for actual donation. According to our data, which includes 502 unrelated donor work-up procedures performed for 425 Dutch patients between 1987 and 2002, one of 11 work-ups ended in the primary requested donor failing to donate. Of all donor-related cancellations (N=46), 78% of the procedures were deferred due to medical reasons and 22% due to nonmedical reasons. Most of the donors deferred for medical reasons were female (P=0.005). In 50% of the cases for which a back-up donor was already identified, the patients were transplanted with a delay of less then 2 weeks; when no back-up donor was available, the median delay increased to 18 weeks. We strongly encourage implementing a search for at least one back-up donor in the primary search. Identifying a back-up donor can save precious time and complicated logistic rescheduling.

Significance of amplified fragment length polymorphism in identification and epidemiological examination of Candida species colonization in children undergoing allogeneic stem cell transplantation

Candida albicans and non-C. albicans Candida species are increasingly being isolated from patients in high-risk categories, most notably, those who have undergone stem cell transplantation (SCT). Identification of the presence of non-C. albicans Candida species early in the course of the transplant procedure is important, as these species exhibit different sensitivities to the available antifungal treatments and cause mortality at rates that vary from those for C. albicans. Amplified fragment length polymorphism (AFLP) analysis has been shown to be a reliable method of reproducibly identifying medically important Candida species. We investigated the use of serial AFLP analysis of 54 routine surveillance cultures for the identification and epidemiological examination of Candida sp. colonization in five consecutive children undergoing allogeneic SCT. One child became colonized with a C. albicans strain and remained colonized with this strain during the whole admission period. Another child had persistent colonization with a C. albicans strain with striking variations in its AFLP patterns over time, which was considered indicative of microevolution. Candida dubliniensis, Candida lusitaniae, and Saccharomyces cerevisiae were identified in the three remaining patients, with two children being simultaneously and transiently colonized with different species. These findings show that colonization with yeasts during transplantation is a complex and dynamic interaction between the host and the organism(s). In our study three strains from eight separate time points were incorrectly identified as C. albicans by a rapid enzyme test. AFLP analysis of surveillance cultures allowed more accurate and informative epidemiological evaluations of pathogenic yeasts in children during transplantation.