Hypomorphic RAG deficiency: impact of disease burden on survival and thymic recovery argues for early diagnosis and HSCT

Patients with hypomorphic mutations in the RAG1 or RAG2 gene present with either Omenn syndrome or atypical combined immunodeficiency with a wide phenotypic range. Hematopoietic stem cell transplantation (HSCT) is potentially curative, but data are scarce. We report on a worldwide cohort of 60 patients with hypomorphic RAG variants who underwent HSCT, 78% of whom experienced infections (29% active at HSCT), 72% had autoimmunity, and 18% had granulomas pretransplant. These complications are frequently associated with organ damage. Eight individuals (13%) were diagnosed by newborn screening or family history. HSCT was performed at a median of 3.4 years (range 0.3-42.9 years) from matched unrelated donors, matched sibling or matched family donors, or mismatched donors in 48%, 22%, and 30% of the patients, respectively. Grafts were T-cell depleted in 15 cases (25%). Overall survival at 1 and 4 years was 77.5% and 67.5% (median follow-up of 39 months). Infection was the main cause of death. In univariable analysis, active infection, organ damage pre-HSCT, T-cell depletion of the graft, and transplant from a mismatched family donor were predictive of worse outcome, whereas organ damage and T-cell depletion remained significant in multivariable analysis (hazard ratio [HR] = 6.01, HR = 8.46, respectively). All patients diagnosed by newborn screening or family history survived. Cumulative incidences of acute and chronic graft-versus-host disease were 35% and 22%, respectively. Cumulative incidences of new-onset autoimmunity was 15%. Immune reconstitution, particularly recovery of naïve CD4+ T cells, was faster and more robust in patients transplanted before 3.5 years of age, and without organ damage. These findings support the indication for early transplantation.

Persistence of HIV reservoir following successful haematopoietic stem cell transplant for juvenile myelomonocytic leukaemia in a child with perinatally acquired HIV

This report describes a case of juvenile myelomonocytic leukaemia (JMML) on a background of both perinatally acquired HIV infection and congenital cytomegalovirus, and management of antiretroviral therapy during haematopoietic stem cell transplant. Peripheral blood HIV viral load remained below the lower limit of detection throughout and following transplant and is currently <20 RNA copies/mL. The child is currently in remission from JMML, but HIV DNA remains detectable despite myeloablative conditioning and sustained plasma HIV viral suppression.

A mass spectrometry method for sensitive, specific and simultaneous detection of bovine blood meal, blood products and milk products in compound feed

Feed sustainability is one of the biggest challenges for the next few years. Solutions have to be found that take feed quality and safety into account. Animal by-products are one valuable source of proteins. However, since the bovine spongiform encephalopathy (BSE) crisis, their use has been strictly regulated. The objective of this study was to propose a routine, sensitive and specific method using ultra-high performance liquid chromatography coupled to tandem mass spectrometry for the detection of blood-derived products and milk powder in feed. Contaminated aquafeeds were analysed in order to evaluate the sensitivity and specificity of the method. This new method meets both selectivity and sensitivity (0.1% (w/w)) requirements imposed by the European Commission for animal proteins detection methods. It offers an innovative and complementary solution for the simultaneously identification of authorised and unauthorised animal by-products such as processed animal proteins (PAPs).

Predicting CD4 T-Cell Reconstitution Following Pediatric Hematopoietic Stem Cell Transplantation

Hematopoietic stem cell transplantation (HSCT) is an increasingly common treatment for children with a range of hematological disorders. Conditioning with cytotoxic chemotherapy and total body irradiation leaves patients severely immunocompromised. T‐cell reconstitution can take several years due to delayed restoration of thymic output. Understanding T‐cell reconstitution in children is complicated by normal immune system maturation, heterogeneous diagnoses, and sparse uneven sampling due to the long time spans involved. We describe here a mechanistic mathematical model for CD4 T‐cell immune reconstitution following pediatric transplantation. Including relevant biology and using mixed‐effects modeling allowed the factors affecting reconstitution to be identified. Bayesian predictions for the long‐term reconstitution trajectories of individual children were then obtained using early post‐transplant data. The model was developed using data from 288 children; its predictive ability validated on data from a further 75 children, with long‐term reconstitution predicted accurately in 81% of the patients.

Vaccination to improve the persistence of CD19CAR gene-modified T cells in relapsed pediatric acute lymphoblastic leukemia

Trials with second generation CD19 chimeric antigen receptors (CAR) T-cells report unprecedented responses but are associated with risk of cytokine release syndrome (CRS). Instead, we studied the use of donor Epstein-Barr virus-specific T-cells (EBV CTL) transduced with a first generation CD19CAR, relying on the endogenous T-cell receptor for proliferation. We conducted a multi-center phase I/II study of donor CD19CAR transduced EBV CTL in pediatric acute lymphoblastic leukaemia (ALL). Patients were eligible pre-emptively if they developed molecular relapse (>5 × 10-4) post first stem cell transplant (SCT), or prophylactically post second SCT. An initial cohort showed poor expansion/persistence. We therefore investigated EBV-directed vaccination to enhance expansion/persistence. Eleven patients were treated. No CRS, neurotoxicity or graft versus host disease (GVHD) was observed. At 1 month, 5 patients were in CR (4 continuing, 1 de novo), 1 PR, 3 had stable disease and 3 no response. At a median follow-up of 12 months, 10 of 11 have relapsed, 2 are alive with disease and 1 alive in CR 3 years. Although CD19CAR CTL expansion was poor, persistence was enhanced by vaccination. Median persistence was 0 (range: 0-28) days without vaccination compared to 56 (range: 0-221) days with vaccination (P=0.06). This study demonstrates the feasibility of multi-center studies of CAR T cell therapy and the potential for enhancing persistence with vaccination.

Identification of specific bovine blood biomarkers with a non-targeted approach using HPLC ESI tandem mass spectrometry

Animal by-products are valuable protein sources in animal nutrition. Among them are blood products and blood meal, which are used as high-quality material for their beneficial effects on growth and health. Within the framework of the feed ban relaxation, the development of complementary methods in order to refine the identification of processed animal proteins remains challenging. The aim of this study was to identify specific biomarkers that would allow the detection of bovine blood products and processed animal proteins using tandem mass spectrometry. Seventeen biomarkers were identified: nine peptides for bovine plasma powder; seven peptides for bovine haemoglobin powder, including six peptides for bovine blood meal; and one peptide for porcine blood. They were not detected in several commercial compound feed or feed materials, such as blood by-products of other animal origins, milk-derived products and fish meal. These biomarkers could be used for developing a species-specific and blood-specific detection method.

No evidence of transfusion transmission of Adenovirus and Epstein-Barr virus infections in paediatric recipients post-bone marrow transplant

Adenovirus and Epstein-Barr virus can cause significant morbidity and mortality in paediatric patients post-bone marrow transplant. The source of infection is thought to be either reactivation of latent viruses or primary infection. We have investigated whether transfusion of blood components from viraemic donors could provide a route of primary infection in these patients and sought the prevalence of viraemia in the blood donor population from England. In 32 linked donor/recipient samples and 300 unselected blood donors, we found no evidence to suggest that these infections in paediatric bone marrow transplant recipients had been acquired from transfused blood components.

Retrospective study of alemtuzumab vs ATG-based conditioning without irradiation for unrelated and matched sibling donor transplants in acquired severe aplastic anemia: a study from the British Society for Blood and Marrow Transplantation

This retrospective national study compared the use of alemtuzumab-based conditioning regimens for hematopoietic SCT (HSCT) in acquired severe aplastic anemia with antithymocyte globulin (ATG)-based regimens. One hundred patients received alemtuzumab and 55 ATG-based regimens. A matched sibling donor (MSD) was used in 87 (56%), matched unrelated donor (MUD) in 60 (39%) and other related or mismatched unrelated donor (UD) in 8 (5%) patients. Engraftment failure occurred in 9% of the alemtuzumab group and 11% of the ATG group. Five-year OS was 90% for the alemtuzumab and 79% for the ATG groups, P=0.11. For UD HSCT, OS of patients was better when using alemtuzumab (88%) compared with ATG (57%), P=0.026, although smaller numbers of patients received ATG. Similar outcomes for MSD HSCT using alemtuzumab or ATG were seen (91% vs 85%, respectively, P=0.562). A lower risk of chronic GVHD (cGVHD) was observed in the alemtuzumab group (11% vs 26%, P=0.031). On multivariate analysis, use of BM as stem cell source was associated with better OS and EFS, and less acute and cGVHD; young age was associated with better EFS and lower risk of graft failure. This large study confirms successful avoidance of irradiation in the conditioning regimens for MUD HSCT patients.

T cell depletion in paediatric stem cell transplantation

Haematopoietic stem cell transplantation (HSCT) can be a curative procedure for a growing number of paediatric diseases, but as the indications for HSCT grow, so does the need to find suitable stem cell donors. When the preferred option of a genoidentical sibling donor is not available alternative donors, including unrelated adult or umbilical cord blood donors, or haploidentical related donors may be considered. Outcome following alternative donor HSCT has improved over the past 20 years but graft-versus-host disease (GvHD) remains a significant obstacle. T cell depletion (TCD) for non-genoidentical grafts aims to reduce the morbidity and mortality associated with GvHD, but this intervention has not led directly to improved survival due to delayed immune reconstitution and increased infections, graft rejection and increased rates of disease relapse. Limited data from the paediatric population, however, suggest some encouraging results for children undergoing haploidentical HSCT: a move from positive selection of CD34(+) haematopoietic stem cells towards negative depletion of specific cell subsets in order to retain useful accessory cells within the graft appears to enhance immune reconstitution and improve disease-free survival. Here we review recent paediatric outcome data for T cell-depleted HSCT, explore the role of serotherapy in conditioning regimens and look at future possibilities to improve outcome, including novel allodepletion techniques, suicide gene therapy and pathogen-specific immunotherapy.

Impact of viral reactivations in the era of pre-emptive antiviral drug therapy following allogeneic haematopoietic SCT in paediatric recipients

While pre-emptive rituximab therapy for EBV has substantially reduced the incidence of post-transplant lymphoproliferative disorder, following allogeneic haematopoietic SCT (HSCT), cytomegalovirus (CMV) and adenovirus (ADV) still contribute to significant morbidity and mortality after HSCT. We therefore aimed to identify high-risk children who could benefit from recent advances in virus-specific immunotherapy, define the impact of viral reactivations on survival and estimate the economic burden of pre-emptive antiviral drug therapy. Between 2005 and 2010, prospective monitoring of 291 paediatric HSCT procedures revealed that reactivation of CMV (16%), ADV (15%) and EBV (11%) was frequent during period of CD4 T-cell lymphopenia (0.15 × 10(9) L(-1); P<0.05). We report significant risk factors for reactivation, most notably the use of serotherapy and development of GVHD (grade II) in the presence of pre-existing infection (ADV) or donor and/or recipient seropositivity (CMV, EBV). Most interestingly, CMV and ADV viraemia were the major independent predictors of mortality (P<0.05). CMV, ADV or EBV viral reactivation caused prolonged hospitalization (P<0.05), accounted for 15% of all mortality and substantially increased the cost of transplantation by ∼£22 500 ($34 000). This provides an economic rationale for targeting high-risk HSCT recipients with interventions such as virus-specific cell therapy.

The use of reduced-intensity stem cell transplantation in haemophagocytic lymphohistiocytosis and Langerhans cell histiocytosis

Allogeneic stem cell transplant is curative for haemophagocytic lymphohistiocytosis (HLH) and refractory Langerhans cell histiocytosis (LCH). However, patients frequently have significant pre-transplant morbidity and there is high TRM. Because HLH is caused by immune dysregulation, we surmised that a reduced-intensity conditioned (RIC) regimen might be sufficient for cure, while decreasing the TRM. In 2006, we reported the outcome of 12 patients treated with RIC SCT from a matched family/unrelated or haploidentical donor. Here we discuss the update of these patients, including a total of 25 patients treated with RIC SCT for HLH and three for LCH. Twenty-one of the twenty-five patients with HLH (84%) are alive and well with remission at a median of 36 months from SCT. Mortality included pneumonitis (n=3) and hepatic rupture (n=1). All three patients treated with RIC SCT for LCH remain alive and in remission at a median of 5.1 years from SCT. Seven of twenty-four survivors (one with LCH) have mixed chimerism but remain disease-free. These data are supported by other groups including 100% survival in seven patients with HLH and 78% survival of nine patients with LCH. In summary, RIC compares favourably with conventional SCT with long-term disease control in surviving patients with both HLH and LCL, despite a significant incidence of mixed chimerism.

Recommendations for a standard UK approach to incorporating umbilical cord blood into clinical transplantation practice: conditioning protocols and donor selection algorithms

Allogeneic haematopoietic cell transplantation is an established curative treatment modality for patients with malignant and non-malignant haematological disorders. Since the first related umbilical cord blood transplant (UCBT) in 1988, the use of UCB as a stem cell source for transplantation has become a standard practice in many countries, with approximately 8000 such transplants having been performed worldwide to date.

Stem cell transplantation for children with Glanzmann thrombasthenia

Glanzmann thrombasthenia (GT) is a rare autosomal recessive platelet function disorder. Stem cell transplantation (SCT) is curative, but it is only indicated in selected patients with a severe clinical phenotype or who develop anti-platelet antibodies. SCT have previously been limited to full intensity myeloablative conditioning regimens. This study details the successful outcome of SCT in five consecutive patients with GT, three of whom received reduced intensity conditioning (RIC) with stem cells from non-sibling donors. This is the first time RIC SCT has been reported in GT, and offers the possibility of curative therapy with reduced late effects.

Reduced intensity conditioning and allogeneic stem cell transplantation in childhood malignant and nonmalignant diseases

Allogeneic hematopoietic SCT is well established as a potentially curative therapy for children and adults with both malignant and nonmalignant diseases. However, myeloablative SCT is associated with significant short- and long-term complications. The goals of a reduced intensity-conditioning (RIC) regimen are to prevent graft rejection and establish stable donor-derived hematopoiesis at a level sufficient for cure of the underlying disease and, in patients with hematologic malignancy, to provide a GVL effect, while decreasing the short- and long-term complications associated with myeloablative conditioning therapy. RIC regimens have enabled SCT to be performed in children with preexisting comorbidities that preclude conventional conditioning. RIC-SCT has been most extensively studied in patients with nonmalignant disorders and for some of these, including primary immunodeficiencies and hemophagocytic lymphohistiocytosis, sufficient data now exist to support its routine use even in patients without comorbidity. Less data exist on RIC-SCT for children with hematologic malignancies and at present this should be restricted to children who are not candidates for, or have relapsed after, myeloablative SCT. Here we review available data on the use of RIC-SCT in pediatric patients, highlighting important clinical lessons and areas that require further study.

The effect of a metaphylactic treatment with diclazuril (Vecoxan®) on the oocyst excretion and growth performance of calves exposed to a natural Eimeria infection

A multicenter field efficacy study was performed in six farms located in Belgium, France and Germany with a history of suspected coccidiosis outbreaks and the proven presence of Eimeria bovis and/or Eimeria zuernii. At each of these trial sites the calves were randomly allocated to two groups (T, treated; C, control) of similar size. In total, 231 calves were included in the study. Group T calves (n=116) were drenched with a single dose of diclazuril (Vecoxan, 1mg/kg body weight) close to the time of expected outbreak of coccidiosis (day 1 of the study period), group C calves (n=115) served as placebo-treated controls. Although E. bovis and/or E. zuernii were identified at all trial sites, clinical coccidiosis was only noted in 16% of the group C calves. At day 5 of the study period (4 days after treatment), faecal oocyst counts (opg, oocysts per gram) were substantially lower in group T ("short-term effect") compared to group C. At four trial sites, the respective values of groups T and C were significantly different (P=0.0132 to P=0.0001) in favour of group T. For the pooled data of all trial sites, this effect was highly significant (P<0.0001). The overall faecal oocyst counts from day 3 until day 21 of the study period ("Area Under the Curve") was significantly reduced in group T by 87.2-99.5% ("long-term effect") at five trial sites (P=0.0139 to P<0.0001). The pooled data revealed a highly significant effect of treatment on oocyst excretion over the observation period (P<0.0001). On five of the six trial sites, the average weight gain was higher in group T than in group C. On those trial sites, the average weight gain of group T calves exceeded that of the controls by 95-268g/day and by 2.0-6.0kg over the study period. This effect was statistically significant (P<0.01) at one trial site. Altogether the calves of group T gained on average 129g more weight daily than the controls (+2.7kg over the study period). For these pooled data, statistical analysis confirmed the positive effect of treatment of calves exposed to coccidiosis on growth performance (P=0.003). In conclusion, metaphylactic treatment with diclazuril efficiently controls coccidiosis in calves thus reducing environmental contamination with oocysts and preventing negative effects of natural exposure to coccidiosis on growth performance of calves.

Outcomes of hematopoietic stem cell transplantation for Hurler's syndrome in Europe: a risk factor analysis for graft failure

Hurler's syndrome (HS), the most severe form of mucopolysaccharidosis type-I, causes progressive deterioration of the central nervous system and death in childhood. Allogeneic stem cell transplantation (SCT) before the age of 2 years halts disease progression. Graft failure limits the success of SCT. We analyzed data on HS patients transplanted in Europe to identify the risk factors for graft failure. We compared outcomes in 146 HS patients transplanted with various conditioning regimens and grafts. Patients were transplanted between 1994 and 2004 and registered to the European Blood and Marrow Transplantation database. Risk factor analysis was performed using logistic regression. ‘Survival’ and ‘alive and engrafted’-rate after first SCT was 85 and 56%, respectively. In multivariable analysis, T-cell depletion (odds ratio (OR) 0.18; 95% confidence interval (CI) 0.04–0.71; P=0.02) and reduced-intensity conditioning (OR 0.08; 95% CI 0.02–0.39; P=0.002) were the risk factors for graft failure. Busulfan targeting protected against graft failure (OR 5.76; 95% CI 1.20–27.54; P=0.028). No difference was noted between cell sources used (bone marrow, peripheral blood stem cells or cord blood (CB)); however, significantly more patients who received CB transplants had full-donor chimerism (OR 9.31; 95% CI 1.06–82.03; P=0.044). These outcomes may impact the safety/efficacy of SCT for ‘inborn-errors of metabolism’ at large. CB increased the likelihood of sustained engraftment associated with normal enzyme levels and could therefore be considered as a preferential cell source in SCT for ‘inborn errors of metabolism’.

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.

Characterisation of a preservative system in an oily preparation

The influence of three variables, i.e. the concentrations of benzyl alcohol (BA), butylated hydroxytoluene (BHT) and tert-butyl-4-hydroxyanisol (BHA), on the preservative efficacy and antioxidant activity of an oily veterinary formulation was investigated using quantitative experimental designs and applying pharmacopoeial methods as part of the robustness-evaluation. Preservative Efficacy Tests (PETs) were performed using the validated European Pharmacpoeia (EP) methodology with 7 test-organisms over one month on lab-scale test-formulations. These were independently prepared according to a Box-Behnken experimental design with a triplicate central point at 0.75% m/V BA, 0.05% mN BHT and 0.05% m/V BHA, and with an additional control-point outside the Box-Behnken cube containing no preservative ingredient. The preservative efficacies were evaluated against the USP and EP criteria for formulations for oral use, as well as by the statistical comparison of the slopes obtained by linear regression of the log of CFU/g versus time. The peroxide values were determined after two months storage at 50 degrees C, using the EP titrimetric method. No interactions between the preservatives were observed for any of the seven tested micro-organisms in the PETs. BA had a very significant preservative effect against several of the tested microorganisms, while no antimicrobial effect for BHT and BHA was observed. Aspergillus niger was the most preservative-resistant micro-organism, while Staphylococcus aureus was the most sensitive test-germ. Compliance with USP-PET criteria was found for all formulations tested, even those without preservatives, while the EP-PET criteria showed compliance for those formulations with the highest BA concentration only. Stored in glass vials, a statistically significant antioxidant effect was demonstrated for BA only, although all tested formulations showed acceptable anti-oxidative properties. No significant antioxidant effects were shown for BHT or BHA.

Haematopoietic cell transplantation (HCT) in combination with enzyme replacement therapy (ERT) in patients with Hurler syndrome

Hurler syndrome (MPS 1H) is the severe form of mucopolysaccharidosis type 1 (MPS 1). Haematopoietic cell transplantation (HCT) is the treatment of choice, but carries a high incidence of graft failure and morbidity. The use of enzyme replacement therapy (ERT) might improve the clinical signs and symptoms before HCT, resulting in less transplantation-related complications. Moreover, clearance of glycosaminoglycans (GAG's) from the bone marrow might improve engraftment. Twenty-two patients with MPS 1H received one or more HCT procedures in combination with ERT. One patient with severe cardiomyopathy improved significantly after ERT. All children were in a relatively good clinical condition before HCT. Of patients 59, 82 and 86% were alive and engrafted after one, two and three HCT procedures, respectively. Two patients died after repetitive HCT. No serious ERT-infusion-related toxicity occurred. ERT with HCT was well tolerated. Neither a positive nor a negative effect on the number of patients who are alive and engrafted after receiving ERT before HCT as compared to a historic cohort was noted. However, patients in a poor clinical condition before HCT might benefit from ERT.

Add-back of allodepleted donor T cells to improve immune reconstitution after haplo-identical stem cell transplantation

Poor immune reconstitution after haplo-identical stem cell transplantation results in high mortality from viral infections and relapse. One approach to overcome this problem is to deplete alloreactive cells selectively by deleting T cells activated by recipient stimulators, using an immunotoxin directed against the activation marker CD25. However, the degree of depletion of alloreactive cells is variable following stimulation with recipient PBMC, and this can result in GvHD. We have shown that using recipient EBV-transformed LCL as stimulators to activate donor alloreactive T cells results in more consistent depletion of in vitro alloreactivity while preserving T-cell responses to viral and potential myeloid tumor Ag. Based on these data, we have embarked on a phase I clinical dose escalation study of add-back of allo-LCL-depleted donor T cells in the haplo-identical setting, to determine if the allodepletion we achieve to allow infusion of sufficient T cells to restore useful antiviral/anti-leukemic responses without causing GvHD. Fifteen patients have so far been treated. The incidence of significant acute or chronic GvHD has been low (2/15), as has mortality from infection (1/15). Preliminary data show accelerated immune reconstitution in dose level 2 patients. Infused allodepleted donor T cells appear able to expand significantly in the face of viral reactivations, and doses as low as 3 x 10(5)/kg may be sufficient to confer useful antiviral immunity in this setting. At a median follow-up of 19.5 months, nine of 15 patients are alive and disease-free. Five patients have relapsed, all of whom have died.

Nijmegen breakage syndrome diagnosed as Fanconi anaemia

BACKGROUND

Fanconi anaemia (FA) and Nijmegen breakage syndrome (NBS) are rare chromosomal instability disorders with overlapping clinical features. It has recently been shown that, like FA, NBS is also associated with increased chromosomal sensitivity to DNA cross-linking agents.

PROCEDURE

We report a family that was initially diagnosed with FA on the basis of increased sensitivity to DNA cross-linking agents. They were atypical in that there were associated severe infection problems. In view of these features we performed immune function studies together with molecular analysis of the FA genes and subsequently the NBS1 gene.

RESULTS

Two children in the kindred have died, one from sepsis, and the other with a plasma cell malignancy. A third child underwent bone marrow transplantation because of recurrent infections. All affected members had severe immunological abnormalities. The genetic defect was shown to be a novel mutation in the NBS1 gene, so the diagnosis was revised to that of NBS.

CONCLUSIONS

This family illustrates the importance of awareness of the lack of specificity of DNA cross-linking agent tests for FA, particularly in situations where the clinical features are atypical. In addition, one of the cases represents the first use of bone marrow transplantation for NBS that we are aware of; this treatment may have a future role for other patients with the syndrome.

Stem cell transplantation for congenital immunodeficiencies using reduced-intensity conditioning

The optimal preparation for stem cell transplantation (SCT) in children with congenital immunodeficiencies is currently unknown. In all, 81 children with immunodeficiency underwent 82 SCTs using reduced-intensity conditioning (RIC). The incidence of significant GVHD was low; viral reactivation was prominent with an unexpected increase in EBV reactivation; immune reconstitution was similar between different donor groups and comparable to conventional SCT. Overall, 68/81 (84%) survive with no significant difference between donor types or between severe combined immunodeficiency (SCID) and non-SCID diseases. Findings suggest a significant survival advantage in the unrelated donor setting for RIC compared to conventional SCT.

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.

Resolution of peanut allergy following bone marrow transplantation for primary immunodeficiency

Peanut allergy is a severe and life-threatening form of food allergy. Treatments are being developed but the mainstays of current management remain avoidance of peanut and appropriate use of rescue medication. We report the case of a boy with peanut allergy who required a bone marrow transplant (BMT) for combined immunodeficiency. A food challenge, 2 years after transplant, showed that his peanut allergy had resolved. Allergic disorders constitute a form of immune deviation and while we do not advocate BMT as a treatment for peanut allergy, we believe this case provides an insight into the basic mechanisms involved in food allergy.

Haematopoetic stem cell transplantation for refractory autoimmune cytopenia

This study describes the outcome of patients receiving haematopoietic stem cell transplantation (HSCT) to treat severe refractory autoimmune cytopenia. The registry of the European Group of Blood and Marrow Transplantation holds data on 36 patients receiving 38 transplants, the first transplant was autologous for 27 and allogeneic for nine patients. Patients had autoimmune haemolytic anaemia (autologous: 5; allogeneic: 2), Evans's syndrome (autologous: 2; allogeneic: 5); immune thrombocytopenia (autologous: 12), pure red cell aplasia (autologous: 4; allogeneic: 1), pure white cell aplasia (autologous: 1; allogeneic 1), or thrombotic thrombocytopenic purpura (autologous: 3). Patients had longstanding disease having failed multiple prior treatments. Among 26 evaluable patients mobilized for autologous HSCT, three died of treatment-related causes, one died of disease progression, seven were non-responders, six patients had transient responses and nine had continuous partial or complete remission. Of the seven evaluable patients receiving allogeneic HSCT, one died of treatment-related complications, one with transient response died of progressive disease and five had a continuous response. Autologous and allogeneic HSCT may induce a response in a subset of patients with autoimmune cytopenia of long duration albeit at the price of considerable toxicity.

Long-term outcome of haematopoietic stem cell transplantation in autosomal recessive osteopetrosis: an EBMT report

A retrospective analysis was made of 122 children who had received an allogeneic haematopoietic stem cell transplantation (HSCT) for autosomal recessive osteopetrosis between 1980 and 2001. The actuarial probabilities of 5 years disease free survival were 73% for recipients of a genotype HLA-identical HSCT (n=40), 43% for recipients of a phenotype HLA-identical or one HLA-antigen mismatch graft from a related donor (n=21), 40% for recipients of a graft from a matched unrelated donor (n=20) and 24% for patients who received a graft from an HLA-haplotype-mismatch related donor (n=41). In the latter group, a trend towards improvement was achieved at the end of the study period (17% before 1994, 45% after 1994, P=0.11). Causes of death after HSCT were graft failure and early transplant-related complications. Severe visual impairment was present in 42% of the children before HSCT. Conservation of vision was better in children transplanted before the age of 3 months. Final height was related to height at the time of HSCT and better preserved in children transplanted early. Most children attended regular school or education for the visually handicapped. At present, HSCT is the only curative treatment for autosomal recessive osteopetrosis and should be offered as early as possible.

Conservative management of pneumatosis intestinalis and pneumoperitoneum following bone-marrow transplantation

Pneumatosis intestinalis (PI), with or without pneumoperitoneum (PP), may complicate allogenic bone-marrow transplantation (BMT). The aim of our study was to establish the incidence and outcome of this complication following BMT in children. A departmental database was used to identify children who underwent BMT in the 4-year period up to December 1999. The medical records of children who developed PI with or without PP were obtained for further study. All patients were managed without recourse to surgery. Conservative management included 7 days of intravenous antibiotics and 10 days of intestinal rest supported by parenteral nutrition. In the study period, 138 BMTs were carried out. Six children (4%) with a total of 7 episodes of PI/PP were identified, 1 boy and 5 girls with a median age of 8.5 years (range 0.8-11). Neutropenia was noted in 3 children at the time of presentation. Other risk factors identified included alternative BMT donors (5/6), steroid therapy (6/7), and graft-versus-host disease (5/6). Organisms were isolated from stool cultures sent at the time of diagnosis in 3 out of 7 instances. Diarrhoea was the predominant presenting symptom. All patients recovered from the acute episode, but 5 died at a mean of 12 months from the development of PI/PP (range 6-17 months). This mortality of 83% compares with a mortality of 33% (43 of 132) for the remainder of children who underwent BMT during the study period. Thus, while initial recovery can be anticipated, the medium-term mortality in this group of children is high.

Non-myeloablative stem cell transplantation for congenital immunodeficiencies

Allogeneic haematopoietic stem cell transplantation (HSCT) can be a highly successful treatment option for individuals with congenital immunodeficiency states. The strategy for HSCT is varied but in cases where there is preservation of residual T cell function, conditioning regimes have been used and have been based around a combination of busulphan and cyclophosphamide with or without serotherapy. In patients with coexisting organ damage this has resulted in significant morbidity and mortality. We have therefore used a low-intensity conditioning regime for transplantation in this group of immunodeficiency patients. Twenty-one patients with a variety of different immunodeficiencies were treated using the following conditioning regimes: (1) fludarabine/melphalan/ATG or Campath 1H (n=16), (2) fludarabine/cyclophosphamide/Campath 1H (n=1), (3) TBI/CyA/MMF (n=1), (4) fludarabine/melphalan/busulphan/ATG (n=3). In 13 cases matched (n=9) and 1 Ag mismatched (n=4) unrelated donors were used and in eight cases transplants from matched siblings (n=4), 1 Ag mismatched sibling (n=1), matched parent (n=1) and haploidentical parents (n=3) were performed. At a median follow-up of 13 months, 19 of 21 (90%) patients were still alive following the transplant procedure. Despite a T cell replete graft and the use of unrelated donor grafts in the majority of patients studied there was no evidence of significant organ disease. Immune reconstitution in terms of CD3+ and CD4+ T cell recovery and function was equivalent in comparison with a historical cohort. We believe that this low-intensity approach has significant implications for transplantation of individuals with immunodeficiency states with established organ disease.

The pore of the leaf cavity of Azolla species: teat cell differentiation and cell wall projections

The differentiation of the specialized secretory teat cells of the leaf cavity pore of Azolla species was investigated at the ultrastructural level with emphasis on their peculiar cell wall projections. The results indicated that the projections are formed as soon as the teat cells complete their differentiation and that their production is principally associated with changes in endoplasmic reticulum profiles. The number of projections increases with the teat cell age and is stimulated under salt and P deficiency stresses. Salt stress also promotes their emergence on Azolla species that under normal conditions do not produce projections. Cytochemical tests on different Azolla species showed that the projection composition is almost identical: proteins, acidic polysaccharides, and pectin are always detected. This study revealed that Azolla teat cell projections differ fundamentally from other types of hitherto described cell wall projections that are considered as remnant structures from cell separation. In contrast, in Azolla teat cells projections are actively produced and compounds are excreted by an exocytotic mechanism. The possible role of the projections in the symbiosis of Azolla spp. with Anabaena azollae is discussed.

Outcome for children after failed transplant for primary haemophagocytic lymphohistiocytosis

Primary haemophagocytic lymphohistiocytosis is a rare disorder of childhood, which is usually fatal without allogeneic stem cell transplantation (SCT). For children who lack a matched family or closely matched unrelated donor, SCT using haploidentical parental stem cells has been used, but is associated with an increased risk of graft failure. The most appropriate subsequent management for those children who survive after graft rejection is currently unclear. We report the outcome for three such children. After a period of disease quiescence lasting 4 months to 8 years, disease recurrence and subsequent death occurred in each case. Accordingly, a second SCT is recommended.

Analysis of chimaerism in thalassaemic children undergoing stem cell transplantation

We have prospectively assessed the relative contribution of host and donor to haemopoiesis following stem cell transplantation (SCT) in children with beta-thalassaemia major (n = 35), using karyotype analysis or Southern blot/polymerase chain reaction analysis of variable number tandem repeats on genomic DNA from peripheral blood. Early haemopoiesis was fully donor in origin in 24 out of 35 cases and remained so throughout the post-transplant course in all but one patient, who evolved to stable mixed chimaerism. The remaining 11 cases (31%) initially showed mixed chimaerism: four of these rejected, one eventually eradicated host haemopoiesis to become fully donor haemopoietic, and the remaining six had persistent mixed chimaerism, with 5--38% host haemopoiesis. The risk of graft rejection was high when > 15% host haemopoiesis was present at 3 months post transplant: four out of six such patients rejected their grafts; conversely, zero out of 29 patients with < 15% host haemopoiesis at 3 months rejected (P < 0.0001). There was a higher incidence of significant acute and chronic graft-versus-host disease in patients with full donor chimaerism. These studies confirm that the mixed chimaeric state is common following SCT for thalassaemia, often persists (with up to 4 years follow-up) and is compatible with long-term cure. Analysis of chimaerism in patients undergoing SCT for beta-thalassaemia enables monitoring of engraftment in the early post-transplant period, provides insight into the biology of engraftment and may be useful in identifying patients at high risk of rejection.