FOXN1 forms higher-order nuclear condensates displaced by mutations causing immunodeficiency

The transcription factor FOXN1 is a master regulator of thymic epithelial cell (TEC) development and function. Here, we demonstrate that FOXN1 expression is differentially regulated during organogenesis and participates in multimolecular nuclear condensates essential for the factor’s transcriptional activity. FOXN1’s C-terminal sequence regulates the diffusion velocity within these aggregates and modulates the binding to proximal gene regulatory regions. These dynamics are altered in a patient with a mutant FOXN1 that is modified in its C-terminal sequence. This mutant is transcriptionally inactive and acts as a dominant negative factor displacing wild-type FOXN1 from condensates and causing athymia and severe lymphopenia in heterozygotes. Expression of the mutated mouse ortholog selectively impairs mouse TEC differentiation, revealing a gene dose dependency for individual TEC subtypes. We have therefore identified the cause for a primary immunodeficiency disease and determined the mechanism by which this FOXN1 gain-of-function mutant mediates its dominant negative effect.

The United Kingdom Primary Immune Deficiency (UKPID) Registry: report of the first 4 years' activity 2008-2012

This report summarizes the establishment of the first national online registry of primary immune deficency in the United Kingdom, the United Kingdom Primary Immunodeficiency (UKPID Registry). This UKPID Registry is based on the European Society for Immune Deficiency (ESID) registry platform, hosted on servers at the Royal Free site of University College, London. It is accessible to users through the website of the United Kingdom Primary Immunodeficiency Network (www.ukpin.org.uk). Twenty-seven centres in the United Kingdom are actively contributing data, with an additional nine centres completing their ethical and governance approvals to participate. This indicates that 36 of 38 (95%) of recognized centres in the United Kingdom have engaged with this project. To date, 2229 patients have been enrolled, with a notable increasing rate of recruitment in the past 12 months. Data are presented on the range of diagnoses recorded, estimated minimum disease prevalence, geographical distribution of patients across the United Kingdom, age at presentation, diagnostic delay, treatment modalities used and evidence of their monitoring and effectiveness.

Lymphoid tumours and breast cancer in ataxia telangiectasia; substantial protective effect of residual ATM kinase activity against childhood tumours

Background:

Immunodeficiency in ataxia telangiectasia (A-T) is less severe in patients expressing some mutant or normal ATM kinase activity. We, therefore, determined whether expression of residual ATM kinase activity also protected against tumour development in A-T.

Methods:

From a total of 296 consecutive genetically confirmed A-T patients from the British Isles and the Netherlands, we identified 66 patients who developed a malignant tumour; 47 lymphoid tumours and 19 non-lymphoid tumours were diagnosed. We determined their ATM mutations, and whether cells from these patients expressed any ATM with residual ATM kinase activity.

Results:

In childhood, total absence of ATM kinase activity was associated, almost exclusively, with development of lymphoid tumours. There was an overwhelming preponderance of tumours in patients <16 years without kinase activity compared with those with some residual activity, consistent with a substantial protective effect of residual ATM kinase activity against tumour development in childhood. In addition, the presence of eight breast cancers in A-T patients, a 30-fold increased risk, establishes breast cancer as part of the A-T phenotype.

Conclusion:

Overall, a spectrum of tumour types is associated with A-T, consistent with involvement of ATM in different mechanisms of tumour formation. Tumour type was influenced by ATM allelic heterogeneity, residual ATM kinase activity and age.

Clinical and immunological manifestations of patients with atypical severe combined immunodeficiency

Hypomorphic mutations in genes associated with severe combined immunodeficiency (SCID) or Omenn syndrome can also cause milder immunodeficiencies. We report 10 new patients with such "atypical" SCID and summarize 63 patients from the literature. The patient groups with T(low)B(low) (n=28), T(low)B(+) (n=16) and ADA (n=29) SCID variants had similar infection profiles but differed in the frequency of immune dysregulation, which was observed predominantly in patients with recombination defects. Most immunological parameters were remarkably similar in the three groups. Of note, 19/68 patients with "atypical" SCID had normal T cell counts, 48/68 had normal IgG and 23/46 had at least one normal specific antibody titer. Elevated IgE was a characteristic feature of ADA deficiency. This overview characterizes "atypical" SCID as a distinct disease with immune dysregulation in addition to infection susceptibility. Lymphopenia, reduced naïve T cells and elevated IgE are suggestive, but not consistent features of the disease.

Haemopoietic stem-cell transplantation with antibody-based minimal-intensity conditioning: a phase 1/2 study

BACKGROUND

Stem-cell transplantation can cure primary immunodeficiencies. However, in patients with pre-existing organ toxicity, patients younger than 1 year, and those with DNA or telomere repair disorders, chemotherapy-based conditioning is poorly tolerated and results in major morbidity and mortality. We tested a novel antibody-based minimal-intensity conditioning (MIC) regimen to assess whether this approach allowed curative donor stem-cell engraftment without non-haemopoietic toxicity.

METHODS

16 high-risk patients underwent stem-cell transplantation for primary immunodeficiencies with an MIC regimen consisting of two rat anti-CD45 monoclonal antibodies YTH 24.5 and YTH 54.12 for myelosuppression, and alemtuzumab (anti-CD52) and fludarabine, and low dose cyclophosphamide for immunosuppression. Donors were matched siblings (n=5), and matched (9) and mismatched (2) unrelated donors.

FINDINGS

Antibody-based conditioning was well tolerated, with only two cases of grade 3 and no grade 4 toxicity. Rates of clinically significant acute (n=6, 36%) and chronic graft-versus-host disease (GVHD) (n=5, 31%) were acceptable. 15 of 16 patients (94%) engrafted, of whom 11 (69%) achieved full or high-level mixed chimerism in both lymphoid and myeloid lineages, and three achieved engraftment in the T-lymphoid lineage only. One patient needed retransplantation. At a median of 40 months post-transplant, 13 of 16 patients (81%) in this high-risk cohort were alive and cured from their underlying disease.

INTERPRETATION

Monoclonal antibody-based conditioning seems well tolerated and can achieve curative engraftment even in patients with severe organ toxicity or DNA repair defects, or both. This novel approach represents a shift from the paradigm that intensive chemotherapy or radiotherapy, or both, is needed for donor stem-cell engraftment. This antibody-based conditioning regimen may reduce toxicity and late effects and enable SCT in virtually any primary immunodeficiency patient with a matched donor.

FUNDING

None.

Immunodeficiency in ataxia telangiectasia is correlated strongly with the presence of two null mutations in the ataxia telangiectasia mutated gene

Immunodeficiency affects over half of all patients with ataxia telangiectasia (A-T) and when present can contribute significantly to morbidity and mortality. A retrospective review of clinical history, immunological findings, ataxia telangiectasia mutated (ATM) enzyme activity and ATM mutation type was conducted on 80 consecutive patients attending the National Clinic for Ataxia Telangiectasia, Nottingham, UK between 1994 and 2006. The aim was to characterize the immunodeficiency in A-T and determine its relationship to the ATM mutations present. Sixty-one patients had mutations resulting in complete loss of ATM kinase activity (group A) and 19 patients had leaky splice or missense mutations resulting in residual kinase activity (group B). There was a significantly higher proportion of patients with recurrent sinopulmonary infections in group A compared with group B (31 of 61 versus four of 19 P = 0.03) and a greater need for prophylactic antibiotics (30 of 61 versus one of 19 P = 0.001). Comparing group A with group B patients, 25 of 46 had undetectable/low immunoglobulin A (IgA) levels compared with none of 19; T cell lymphopenia was found in 28 of 56 compared with one of 18 and B cell lymphopenia in 35 of 55 compared with four of 18 patients (P = 0.00004, 0.001 and 0.003 respectively). Low IgG2 subclass levels and low levels of antibodies to pneumococcal polysaccharide were more common in group A than group B (16 of 27 versus one of 11 P = 0.01; 34/43 versus six of 17 P = 0.002) patients. Ig replacement therapy was required in 10 (12.5%) of the whole cohort, all in group A. In conclusion, A-T patients with no ATM kinase activity had a markedly more severe immunological phenotype than those expressing low levels of ATM activity.

Clinical spectrum of immunodeficiency, centromeric instability and facial dysmorphism (ICF syndrome)

BACKGROUND

Immunodeficiency, centromeric instability and facial dysmorphism (ICF syndrome) is a rare autosomal recessive disease characterised by facial dysmorphism, immunoglobulin deficiency and branching of chromosomes 1, 9 and 16 after PHA stimulation of lymphocytes. Hypomethylation of DNA of a small fraction of the genome is an unusual feature of ICF patients which is explained by mutations in the DNA methyltransferase gene DNMT3B in some, but not all, ICF patients.

OBJECTIVE

To obtain a comprehensive description of the clinical features of this syndrome as well as genotype-phenotype correlations in ICF patients.

METHODS

Data on ICF patients were obtained by literature search and additional information by means of questionnaires to corresponding authors.

RESULTS AND CONCLUSIONS

45 patients all with proven centromeric instability were included in this study. Facial dysmorphism was found to be a common characteristic (n = 41/42), especially epicanthic folds, hypertelorism, flat nasal bridge and low set ears. Hypo- or agammaglobulinaemia was demonstrated in nearly all patients (n = 39/44). Opportunistic infections were seen in several patients, pointing to a T cell dysfunction. Haematological malignancy was documented in two patients. Life expectancy of ICF patients is poor, especially those with severe infections in infancy or chronic gastrointestinal problems and failure to thrive. Early diagnosis of ICF is important since early introduction of immunoglobulin supplementation can improve the course of the disease. Allogeneic stem cell transplantation should be considered as a therapeutic option in patients with severe infections or failure to thrive. Only 19 of 34 patients showed mutations in DNMT3B, suggesting genetic heterogeneity. No genotype-phenotype correlation was found between patients with and without DNMT3B mutations.

Rituximab for the treatment of autoimmune cytopenias in children with immune deficiency

Autoimmune cytopenias are well recognised in patients with primary immune deficiency, but treatment may be difficult. We report eight children with autoimmune cytopenias (autoimmune haemolytic anaemia, autoimmune thrombocytopenia, autoimmune neutropenia) complicating immune deficiency states (common variable immunodeficiency, Wiskott-Aldrich Syndrome, autoimmune lymphoproliferative syndrome, combined immunodeficiency) treated with between 1 and 3 courses of rituximab (anti-CD20). Responses occurred for 90% of treatments but relapse rates (after a median of 53 weeks) were high (78%). We conclude that rituximab is an effective treatment for autoimmune cytopenias in children with immune deficiencies, but repeated courses of treatment may be needed.

Prevalence of SAP gene defects in male patients diagnosed with common variable immunodeficiency

The molecular basis of common variable immunodeficiency (CVID) is undefined, and diagnosis requires exclusion of other diseases including X-linked lymphoproliferative disease (XLP). This rare disorder of immunedysregulation presents typically after Epstein-Barr virus infection and results from defects in the SAP (SLAM associated protein) gene. SAP mutations have been found in a few patients diagnosed previously as CVID, suggesting that XLP may mimic CVID, but no large-scale analysis of CVID patients has been undertaken. We therefore analysed 60 male CVID and hypogammaglobulinaemic patients for abnormalities in SAP protein expression and for mutations in the SAP gene. In this study only one individual, who was found later to have an X-linked family history, was found to have a genomic mutation leading to abnormal SAP cDNA and protein expression. These results demonstrate that SAP defects are rarely observed in CVID patients. We suggest that routine screening of SAP may only be necessary in patients with other suggestive clinical features.

Pneumococcal vaccines for sickle cell disease

BACKGROUND

People with sickle cell disease are particularly susceptible to pneumococcal infection, which may be fatal. Infants (children aged up to 23 months) are at particularly high risk, but conventional polysaccharide pneumococcal vaccines may be ineffective in this age group. New conjugate pneumococcal vaccines are now available, which may help to reduce the incidence of infection in people with sickle cell disease.

OBJECTIVES

To determine the efficacy of pneumococcal vaccines for reducing morbidity and mortality in people with sickle cell disease.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group trials register, comprising of references identified from comprehensive electronic database searches and hand searching relevant journals and abstract books of conference proceedings. In addition, we contacted relevant pharmaceutical companies and experts in the field.Date of most recent search of Group's trials register: November 2003.

SELECTION CRITERIA

All randomised and quasi-randomised controlled trials comparing a polysaccharide or conjugate pneumococcal vaccine regimen with a different regimen or no vaccination in people with sickle cell disease.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected studies for inclusion, extracted data and assessed trial quality.

MAIN RESULTS

Nine trials were identified in the searches and five trials, with a total of 547 participants, met the inclusion criteria. Only one trial reported incidence of pneumococcal infection, and this demonstrated that the polysaccharide pneumococcal vaccine used (PPV14) failed to significantly reduce the risk of infection in children under three years of age, but was associated with only minor adverse events. Three trials of conjugate pneumococcal vaccines found that immune response was increased compared to control groups, including in infants, although clinical outcomes were not measured in these trials.

REVIEWER'S CONCLUSIONS

Previous trials have shown that conjugate pneumococcal vaccines are safe and effective in normal healthy patients, even those under the age of two years. The controlled trials included in this review have demonstrated immunogenicity (the body's response, without which there is no protection) of these vaccines, and observational studies in people with sickle cell disease support these findings. We therefore recommend that conjugate pneumococcal vaccines are used in people with sickle cell disease. Randomised trials in patients with sickle cell disease will be needed to determine the optimal vaccination regimen when further, potentially more effective vaccines become available. Such trials should measure clinical outcomes of effectiveness.

Isolated EBV lymphoproliferative disease in a child with Wiskott-Aldrich syndrome manifesting as cutaneous lymphomatoid granulomatosis and responsive to anti-CD20 immunotherapy

Patients with primary immunodeficiencies such as the Wiskott-Aldrich syndrome (WAS) are prone to develop Epstein-Barr virus (EBV) related lymphoproliferative disorders (LPDs). EBV LPD is most frequently seen in patients receiving immunosuppressive treatment after organ transplantation (post-transplant lymphoproliferative disorder), but can also arise in the primary immunodeficiencies. Typically, EBV LPD presents as a diffuse systemic disease with lymphadenopathy and organ involvement. A rare angiocentric and angiodestructive form of EBV associated B cell LPD, lymphomatoid granulomatosis (LyG), has also been reported in association with WAS. LyG most commonly involves the lung, but can also be seen in brain, kidney, liver, and skin. This report describes the case of a 16 year old boy with WAS who presented with an isolated non-healing ulcerating skin lesion. Biopsy revealed an EBV related LPD with the histological features of LyG. This cutaneous lesion responded dramatically to treatment with specific anti-CD20 immunotherapy and the patient remains clinically free of LPD at 18 months.

X-linked lymphoproliferative disease: three atypical cases

Common variable immunodeficiency (CVID) is the most frequently occurring primary immunodeficiency in both children and adults. The molecular basis of CVID has not been defined, and diagnosis involves exclusion of other molecularly defined disorders. X-linked lymphoproliferative disease (XLP) is a rare disorder in which severe immunodysregulatory phenomena typically follow Epstein-Barr virus (EBV) infection. Boys who survive initial EBV infection have a high incidence of severe complications, including progressive immunodeficiency, aplastic anaemia, lymphoproliferative disease and lymphoma. Survival beyond the second decade is unusual, although bone marrow transplantation can be curative. Until recently reliable diagnostic testing for XLP has not been available, but the identification of the XLP gene, known as SH2D1A, and coding for a protein known as SAP, means that molecular diagnosis is now possible, both by protein expression assays, and mutation detection, although the mutation detection rate in several series is only 55-60%. We describe three male patients initially diagnosed as affected by CVID, one of whom developed fatal complications suggestive of XLP, and all of whom lack expression of SAP. Two out of three have disease-causing mutations in the SAP gene, consistent with published data for XLP. These findings raise the possibility that a subgroup of patients with CVID may be phenotypic variants of XLP. Further studies are necessary to investigate this possibility, and also to clarify the prognostic significance of SAP abnormalities in such patients in the absence of typical features of XLP.

Defective expression of the interleukin-2/interleukin-15 receptor beta subunit leads to a natural killer cell-deficient form of severe combined immunodeficiency

Development of T and natural killer (NK) cells is critically dependent on cytokine signaling, and defects in cytokine receptor complex subunits have been shown to result in severe combined immunodeficiency (SCID) syndromes in humans and in murine models. An infant boy had typical clinical features of SCID and was found to lack NK cells in his peripheral circulation. Molecular analysis did not reveal abnormalities in his gammac or JAK-3 genes, and he was investigated for defects in the interleukin-15 (IL-15) receptor complex because functional IL-15 signaling is essential for NK cell development. Expression of the IL-2R/IL-15Rbeta chain was significantly reduced in the patient's peripheral blood mononuclear cells (PBMCs) by immunoblot, flow cytometry, and Northern blot analysis. Furthermore, IL-2 stimulation of PBMCs showed only minimal tyrosine phosphorylation of JAK-3. These data demonstrate that defects in IL-2R/1L-15Rbeta expression can lead to a unique NK-deficient SCID immunophenotype. (Blood. 2001;98:877-879)

Protein assays for diagnosis of Wiskott-Aldrich syndrome and X-linked thrombocytopenia

Mutations in the gene encoding the Wiskott-Aldrich syndrome protein (WASp) give rise to Wiskott-Aldrich syndrome (WAS), a condition that exhibits a wide spectrum of clinical severity. Patients may develop mild thrombocytopenia or suffer from a wide range of associated disorders including eczema, immune dysfunction, autoimmune disease and malignancy. The clinical diagnosis of Wiskott-Aldrich syndrome (WAS) can be difficult and is usually supported by the detection of WASp gene mutations using genetic analysis. Recently, protein-based assays have been used to demonstrate the absence of WASp in patients known to have WASp gene mutations. We have now reversed this approach and report on the use of immunoblot assays to rapidly diagnose WAS in 13 patients. There was a complete absence of WASp in 10 out of 13 patients and an abnormal protein form was detected in the remaining three patients. In all cases, subsequent genetic analysis confirmed the presence of a WASp gene mutation. We believe that protein-based assays should be employed as the first line of investigation in the diagnosis of WAS spectrum disorders.

A trial of recombinant human granulocyte colony stimulating factor for the treatment of very low birthweight infants with presumed sepsis and neutropenia

OBJECTIVES

The primary objective was to investigate the safety of recombinant human granulocyte colony stimulating factor (rhG-CSF) for the treatment of very low birthweight infants (VLBW) with sepsis and relative neutropenia, specifically with regard to worsening of respiratory distress and thrombocytopenia and all cause mortality. Secondary objectives were to evaluate duration of ventilation, intensive care, and antibiotic use as markers of efficacy.

DESIGN

Neonates (< or = 28 days) in intensive care, with birth weights of 500-1500 g, absolute neutrophil count (ANC) of < or = 5 x 10(9)/l, and clinical evidence of sepsis, were randomly assigned to receive either rhG-CSF (10 microg/kg/day) administered intravenously (n = 13), or placebo (n = 15) for a maximum of 14 days, in addition to standard treatment and antibiotics. All adverse events, oxygenation index, incidence of thrombocytopenia, all cause mortality, duration of ventilation, intensive care and antibiotic treatment, and ANC recovery were compared between the two groups.

RESULTS

Adverse events and oxygenation index were not increased by, and thrombocytopenia was not attributable to, treatment with rhG-CSF. At 6 and 12 months postmenstrual age, there were significantly fewer deaths in the group receiving rhG-CSF (1/13 v 7/15; p < or = 0.038). There was a non-significant trend towards a reduction in duration of ventilation, intensive care, and antibiotic use in the rhG-CSF group. There was a significantly more rapid increase in ANC in the rhG-CSF treated babies (p < 0.001).

CONCLUSIONS

In a small randomised placebo controlled trial in a highly selected group of neonates, adjuvant treatment with rhG-CSF increased ANC rapidly, and no treatment related adverse events were identified. Mortality at 6 and 12 months postmenstrual age was significantly lower in the treatment group. A large trial investigating efficacy in a similar group of neonates is warranted.

Rapid protein-based assays for the diagnosis of T-B+ severe combined immunodeficiency

The severe combined immunodeficiencies (SCID) are a heterogeneous group of conditions arising from a variety of molecular defects. The X-linked form of SCID (X-SCID) is caused by defects in the common gamma chain (gammac), and is characterized by a T-B+NK- immunophenotype. This lymphocyte profile is seen in an autosomal recessive form of SCID caused by mutations in the JAK3 molecule. Thus, X-SCID and JAK3-deficient SCID are clinically and immunologically indistinguishable. Knowledge of the precise molecular defect is essential for antenatal diagnosis, carrier testing and for treatment using somatic gene therapy. To identify the molecular defect in children presenting with a T-B+NK- form of SCID, we have developed rapid assays based on flow cytometric analysis of gammac, immunoblotting for JAK3 and gammac, and detection of interleukin-2 (IL-2)-induced tyrosine phosphorylation of JAK3. Sixteen T-B+NK- SCID patients from 15 families were examined. Nine had no detectable gammac, four had abnormal gammac expression and no IL-2-induced JAK3 tyrosine phosphorylation, and one had normal gammac expression but no IL-2-induced JAK3 tyrosine phosphorylation, although JAK3 was present. All these patients had mutations identified in their gammac gene. Two patients exhibited normal gammac expression, but JAK3 was not detected by immunoblotting and these patients were confirmed as having JAK3 gene mutations. Thus, these protein-based assays have led to rapid molecular diagnoses in T-B+ SCID that have subsequently been confirmed by genetic analysis.

Demystified...adhesion molecule deficiencies

The basic physiology of leucocyte emigration from the intravascular space into the tissues is now known to be dependent on a class of cell surface molecules that have come to be known as adhesion molecules. Many cell-cell interactions are dependent on adhesion and signal transduction via the various adhesion molecules, particularly the integrins. The study of the functions of these molecules has been enhanced by the development of blocking and activating monoclonal antibodies, knockout mice, and by the rare "experiments of nature" in the human population, in whom there is absence or dysfunction of one of the adhesion molecules. This review describes these leucocyte adhesion defects and discusses how they have provided important insights into the function of these molecules.

Genetic variation in ICF syndrome: evidence for genetic heterogeneity

ICF syndrome is a rare autosomal recessive immunoglobulin deficiency, sometimes combined with defective cellular immunity. Other features that are frequently observed in ICF syndrome patients include facial dysmorphism, developmental delay, and recurrent infections. The most diagnostic feature of ICF syndrome is the branching of chromosomes 1, 9, and 16 due to pericentromeric instability. Positional candidate cloning recently discovered the de novo DNA methyltransferase 3B (DNMT3B) as the responsible gene by identifying seven different mutations in nine ICF patients. DNMT3B specifically methylates repeat sequences adjacent to the centromeres of chromosome 1, 9, and 16. Our panel of 14 ICF patients was subjected to mutation analysis in the DNMT3B gene. Mutations in DNMT3B were discovered in only nine of our 14 ICF patients. Moreover, two ICF patients from consanguineous families who did not show autozygosity (i.e. homozygosity by descent) for the DNMT3B locus did not reveal DNMT3B mutations, suggesting genetic heterogeneity for this disease. Mutation analysis revealed 11 different mutations, including seven novel ones: eight different missense mutations, two different nonsense mutations, and a splice-site mutation leading to the insertion of three aa's. The missense mutations occurred in or near the catalytic domain of DNMT3B protein, indicating a possible interference with the normal functioning of the enzyme. However, none of the ICF patients was homozygous for a nonsense allele, suggesting that absence of this enzyme is not compatible with life. Compound heterozygosity for a missense and a nonsense mutation did not seem to correlate with a more severe phenotype.

Clinical course of patients with major histocompatibility complex class II deficiency

The clinical course of 10 children who have been diagnosed with major histocompatibility complex (MHC) class II deficiency (bare lymphocyte syndrome) in the UK over the past eight years is described. They have had a generally poor prognosis, with only two of the 10 still alive despite eight attempts at bone marrow transplantation in six patients. Overwhelming viral infection was the predominant cause of death. Alternative transplant strategies or novel therapies are required for these patients.

Diagnosis of X-linked lymphoproliferative disease by analysis of SLAM-associated protein expression

X-linked lymphoproliferative disease (XLP) is an inherited immunodeficiency in which affected boys show abnormal responses to Epstein-Barr virus infection. The gene defective in XLP has been identified and designated SH2D1A and encodes a protein termed SLAM-associated protein (SAP). Mutation analysis in individuals with typical XLP presentations and family histories has only detected abnormalities in approximately 60% of patients. Thus, genetic analysis alone cannot confirm a diagnosis of XLP We have developed a SAP expression assay that can be used as a diagnostic indicator of XLP We show that SAP is constitutively expressed in normal individuals, in patients with severe sepsis and in patients with other primary immunodeficiencies. In six XLP patients, four with classical and two with atypical presentations, SAP expression was absent. In the latter two, who were previously assigned as having common variable immunodeficiency (CVID), the diagnosis of XLP was initially made using the protein expression assay. In two further patients in whom no mutation could be detected by genetic analysis, lack of SAP expression strongly suggests that these individuals have XLP. We therefore suggest that XLP should be suspected in certain boys previously diagnosed as having CVID and recommend that patients are investigated both by genetic analysis of SH2D1A and by expression of SAP protein.

Absence of platelet CD40L identifies patients with X-linked hyper IgM syndrome

CD40 ligand (CD40L), a membrane protein expressed on activated T cells, plays a pivotal role in B cell proliferation and differentiation. Mutations in the CD40L gene are associated with a rare immunodeficiency state, X-linked hyper IgM syndrome (XLHIGM). Recently, platelets have been described as capable of expressing CD40L within minutes of stimulation. We have developed a rapid technique to determine expression of CD40L on activated platelets by flow cytometry in whole blood. We have demonstrated that this technique is useful in neonatal screening, in rapid diagnosis and in determining reconstitution by donor bone marrow post-transplantation.

Pyoderma gangrenosum in a child with congenital partial deficiency of leucocyte adherence glycoproteins

Congenital deficiency of beta 2 integrin leucocyte adhesion molecules is a rare immunodeficiency and is often fatal. Neutrophils are unable to bind to ligands on the endothelium, and so cannot leave the circulation during inflammation or infection. When leucocyte adhesion deficiency (LAD) is caused by abnormally low expression of beta 2 integrins, it is termed LAD type 1. We describe a 5-year-old girl with a history of recurrent bacterial infections since early childhood who developed necrotic skin ulcers resembling pyoderma gangrenosum and a persistent circulating neutrophilia. Histologically, the lesions showed deep ulceration with a diffuse lymphohistiocytic infiltrate, but with a relative sparsity of neutrophils. Subsequent investigation revealed a complete absence of CD11a/CD18 beta 2 integrins on the surface of the patient's neutrophils, confirming the diagnosis of LAD type 1. The ulcers responded to treatment with oral prednisolone and colchicine.

A simple flow cytometry assay using dihydrorhodamine for the measurement of the neutrophil respiratory burst in whole blood: comparison with the quantitative nitrobluetetrazolium test

The neutrophil respiratory burst is essential for the host's ability to kill ingested microorganisms. Several flow cytometric assays have recently been developed to measure this process. These assays are largely unvalidated. In this study a whole blood flow cytometry assay using dihydrorhodamine 123 (DHR) as a substrate was compared with the quantitative nitrobluetetrazolium (NBT) test, an accepted measure of the earliest events in the respiratory burst. Because whole blood is used, the new assay is quicker and simpler than existing flow cytometry assays. Specimens as small as 0.1 ml can be used which makes the assay ideal for use in neonates and young children. There was a high degree of correlation between the DHR assay and the quantitative NBT test (r(s) = 0.76, P < 0.01). It is concluded that the whole blood DHR assay is an accurate and sensitive measure of the respiratory burst.

The economics of a pharmacy-based central intravenous additive service for paediatric patients

This study was designed to compare the costs of a pharmacy-based Central Intravenous Additive Service (CIVAS) with those of traditional ward-based preparation of intravenous doses for a paediatric population. Labour costs were derived from timings of preparation of individual doses in both the pharmacy and ward by an independent observer. The use of disposables and diluents was recorded and their acquisition costs apportioned to the cost of each dose prepared. Data were collected from 20 CIVAS sessions (501 doses) and 26 ward-based sessions (30 doses). In addition, the costs avoided by the use of part vials in CIVAS was calculated. This was derived from a total of 50 CIVAS sessions. Labour, disposable and diluent costs were significantly lower for CIVAS compared with ward-based preparation (p < 0.001). The ratio of costs per dose [in 1994 pounds sterling] between ward and pharmacy was 2.35:1 (2.51 pounds:1.07 pounds). Sensitivity analysis of the best and worst staff mixes in both locations ranged from 2.3:1 to 4.0:1, always in favour of CIVAS. There were considerable costs avoided in CIVAS from the multiple use of vials; the estimated annual sum derived from the study was 44,000 pounds. In addition, CIVAS was less vulnerable to unanticipated interruptions in work flow than ward-based preparation. CIVAS for children was more economical than traditional ward-based preparation, because of a cost-minimisation effect. Sensitivity analysis showed that these advantages were maintained over a full range of skill mixes. Additionally, significant savings accrued from the multiple use of vials in CIVAS.

Enteroviral pharyngitis diagnosed by reverse transcriptase-polymerase chain reaction

The role of enteroviruses in childhood pharyngitis was investigated using enteroviral specific reverse transcriptase-polymerase chain reaction (RT-PCR). Viral/bacterial throat swabs were taken from 50 children with acute pharyngitis and 26 controls. A positive culture was identified in only 26% of children with pharyngitis (adenovirus 10%, group A streptococci 2%), and none of the controls. Enteroviral RT-PCR was positive in 8% of the pharyngitis group and none of the controls. Enteroviruses are an important cause of pharyngitis in childhood.

Campath-1G in vivo confers a low incidence of graft-versus-host disease associated with a high incidence of mixed chimaerism after bone marrow transplantation for severe aplastic anaemia using HLA-identical sibling donors

We have evaluated the effect of in vivo Campath-1G on engraftment and GVHD in 23 patients with severe aplastic anaemia transplanted from HLA-identical sibling donors. In 14 patients Campath 1g was given pre-transplant for up to 9 days in an attempt to overcome graft rejection (group 1). In nine patients Campath-1G was given pre-transplant, but also continued post-transplant until day +5 to reduce GVHD (group 2). There were three patients with late graft failure in group I following initial neutrophil engraftment, and four cases of grade II+ GVHD. In group II, two patients had early graft failure (no take), and there were no cases of acute GVHD out of seven evaluable patients. One patient in group I developed chronic GVHD of the liver, and two patients (one in each group) had transient localised chronic GVHD. PCR of short tandem repeats was used to evaluate chimaeric status in 13 patients. Of 11 patients with initial neutrophil engraftment, only one had 100% donor haemopoiesis at all times. The remaining patients had either transient mixed chimaerism or persistence of recipient (< 20%) cells. We conclude that in vivo Campath-1G is associated with a high incidence of mixed chimaerism which tips the balance away from GVHD but towards graft rejection.

An audit of early wound infection after elective orthopaedic surgery

The incidence of early post-operative wound infection was studied prospectively in 1053 patients undergoing elective orthopaedic procedures over a 3-month period. The study was repeated in 1131 patients a year later, 6 months after the hospital had moved to new premises. A clinical definition of wound infection identified disturbingly high sepsis rates. A total of 44% of all infections occurred after discharge from hospital. Despite the large sample, there was no significant difference in the rate of early wound infection between the two periods (7.85 and 6.82%). There was no significant difference in infection rates between theatres with and without laminar air flow. In the majority (35 out of 53) of minor infections, bacteriological confirmation was not available because no microbiological specimens were received. Conversely, there were five negative swabs out of 16 wounds defined clinically as major infections. We conclude that, where the rate of bacteriological confirmation of wound infection is low, the use of a clinical definition gives higher audited sepsis rates. Large audit samples are required to demonstrate differences as a result of a changed practice.

The in vitro effects of granulocyte and granulocyte-macrophage colony-stimulating factor on interleukin-3-dependent proliferation of human neonatal circulating progenitor cells

Recombinant human granulocyte (rhG) colony-stimulating factor (CSF) and recombinant human granulocyte-macrophage (rhGM) CSF have been used to enhance neonatal neutrophil host defense. We aimed to determine the comparative efficacy of rhG-CSF and rhGM-CSF in increasing numbers of granulocyte colony-forming unit (CFU-G) and granulocyte-macrophage colony-forming unit (CFU-GM) in recombinant human (rh) IL-3-dependent cultures of human neonatal circulating hematopoietic progenitor cells, including cells from infants born to hypertensive mothers. We also investigated the relationship between fractional increase in CFU-G and endogenous plasma concentration of G-CSF. Circulating mononuclear cells were harvested from 25 neonates, and standard short-term assays in semisolid agar were established in the presence of rhIL-3 alone, rhIL-3 with rhG-CSF and rhGM-CSF, and both rhG-CSF and rhGM-CSF. CFU-G and CFU-GM were counted on d 14. Total colony number and CFU-G were significantly greater in cultures supplemented with rhG-CSF, with or without rhGM-CSF (p < 0.001 and p < 0.0005 for total colony number and CFU-G, respectively), when compared with cultures with rhIL-3 alone. Progenitor cells from three infants born to hypertensive mothers responded similarly. Total colony numbers and CFU-G were not increased by rhGM-CSF alone or by addition of rhGM-CSF to rhG-CSF; however, the proportions of CFU-GM were (p < 0.05 and p < 0.001, respectively, compared with rhIL-3 alone).(ABSTRACT TRUNCATED AT 250 WORDS)

Familial disseminated atypical mycobacterial infection in childhood: a human mycobacterial susceptibility gene?

Inherited defects in specific components of the immune system have provided many clues to the immunological mechanisms underlying resistance to microbial infection. We report a familial immune defect predisposing to disseminated atypical mycobacterial infection in childhood. 6 children with disseminated atypical mycobacterial infection and no recognised form of immunodeficency were identified. Four, including two brothers, come from a village in Malta, and two are brothers of Greek Cypriot origin. They presented with fever, weight loss, lymphadenopathy, and hepatosplenomegaly. They had anaemia and an acute phase response. A range of different mycobacteria (Mycobacterium fortuitum, M chelonei, and four strains of M avium intracellulare complex) were isolated. Treatment with multiple antibiotics failed to eradicate the infection, although treatment with gamma interferon was associated with improvement. Three have died and the surviving children have chronic infection. Tumour necrosis factor-alpha production in response to endotoxin and gamma-interferon was found to be defective in affected patients and their parents. T-cell proliferative responses to mycobacterial and recall antigens were reduced in parents of affected children and gamma-interferon production was diminished in the affected patients and their parents. Clinical and immunological features suggest that these patients are phenotypically similar to Lsh/Ity/Bcg susceptible mice. Understanding of this defect may provide insights into the mechanisms responsible for susceptibility to mycobacteria.

Granulocyte colony stimulating factor treatment for neonatal neutropenia

In a pilot study recombinant human granulocyte colony-stimulating factor (rhG-CSF) was administered to 12 neutropenic preterm infants to determine if neonatal neutropenia is secondary to decreased endogenous G-CSF production. Respiratory variables were monitored because of the possible link between inflammatory cells and hyaline membrane disease. All infants showed increased neutrophil counts. The only possible side effect observed was an exacerbation of thrombocytopenia.

Toledo type brachyolmia

Brachyolmia is a form of spondylodysplasia that has not to the authors' knowledge been described in the UK. It may be a cause of short stature that is currently unrecognised. A case of an 11 year old boy with clinical, radiographic, and eye findings consistent with Toledo type brachyolmia is reported.

Fever of unknown origin in childhood: difficulties in diagnosis

We have described a child with systemic onset juvenile chronic arthritis who presented initially with fever of unknown origin. Treatment of a presumed infection led to a severe allergic response with Stevens-Johnson syndrome, renal failure and DIC. This reaction obscured the features of the underlying disease and delayed the diagnosis.

Liposomal amphotericin B in hepatic candidosis

A 4 year old girl treated with a standard chemotherapy protocol for acute lymphoblastic leukaemia developed hepatic candidosis during the consolidation phase. This relapsed after a prolonged course of amphotericin B and flucytosine. An eight week course of liposomal amphotericin produced a marked clinical improvement which was sustained for one year. A subsequent relapse was associated with transformation to myelodysplastic leukaemia.

Plasma granulocyte-colony stimulating factor concentrations ([G-CSF]) in the early neonatal period

We studied G-CSF concentrations ([G-CSF]) at birth and their relationship with neutrophil count, incidence of infection, gestational age, labour, and the presence of maternal pregnancy-induced hypertension. Plasma [G-CSF] were significantly elevated in babies with suspected infection and in those of hypertensive mothers, compared to healthy babies delivered by elective caesarian section (median [range] = 3101 [75- > 5000] pg/ml and 153 [45-857] pg/ml versus 32 [11-266] pg/ml; P < 0.0001); and were unrelated to neutrophil count and gestational age. Initial high concentrations (> 100 pg/ml) declined by 7 d (P < 0.0001).

Encephalopathy associated with Salmonella enteritidis infection

A 15-year-old boy who presented with a short history of a diarrhoeal illness associated with encephalopathic features is described. Salmonella enteritidis phage type 4 was cultured from his stool. Although encephalopathy in the absence of CNS infection or electrolyte disturbance is well described in enteric fever, it is very rare in infections with non-typhoidal Salmonella serotypes and has not previously been described in association with S. enteritidis infection.

Pseudomonal supraglottitis occurring in a patient with profound neutropenia secondary to virus-associated haemophagocytic syndrome

We present a case of virus-associated haemophagocytic syndrome following Epstein-Barr virus infection in which a fulminant pseudomonal supraglottitis developed. Increasingly, unusual pathogens have been found in immunocompromised patients. This is the first reported case of pseudomonal supraglottitis.

Validation and reproducibility of bidirectional laser Doppler velocimetry for the measurement of retinal blood flow

Bidirectional laser Doppler velocimetry (BLDV) for the measurement of retinal blood flow was validated in six anaesthetised minipigs, by comparing BLDV derived results with those obtained using radioactively labelled microspheres (RLM). The mean velocity of blood (Vmean) was calculated from the maximum red blood cell velocity measured by BLDV. Volumetric flow rate was determined from Vmean and vessel diameter, measure from monochromatic fundus photographs. Total retinal blood flow (TRBF) was calculated by summating flow values obtained for each retinal vein draining into the optic disc. A significant correlation was found between the TRBF results obtained by the two techniques (r = 0.99, p less than 0.001). The BLDV results were between 3-35 microliters/min lower than the corresponding RLM results (p = 0.05). Values of 57 +/- 24 microliters/min and 76 +/- 34 microliters/min were obtained for TRBF using the BLDV and RLM techniques respectively. Reproducibility studies with BLDV were also performed in six anaesthetised pigs over three hours and in six normal human volunteers over two hours and two weeks. No significant difference between measurements was found with time. Ninety five percent confidence limits of +/- 9.8% for the six pigs and +/- 8.9% for the six human volunteers were found for measurements on the same day and at two weeks. We conclude that with a sample size of six, changes in flow of approximately 20% can be detected using BLDV and monochromatic fundus photography.

A laser Doppler velocimetry study of the effect of hypoglycaemia on retinal blood flow in the minipig

The effect of acute hypoglycaemia (plasma glucose less than 2.2 mmol/l) on retinal venous blood flow in the minipig has been determined using bidirectional laser Doppler velocimetry and red free retinal photography. In six pigs the mean flow in a retinal vein increased from 19.3 (+/- 2.8 SEM) microliters/min to 29.7 (+/- 7.5) microliters/min during hypoglycaemia (p less than 0.05) with a return to 18.6 (+/- 3.6) microliters/min when euglycaemia was restored. Retinal blood flow is affected by hypoglycaemia or its haemodynamic consequences.

Restrictive dermopathy: a report of three cases

We report three infants with a rare syndrome of restrictive dermopathy, in which rigidity of the skin at birth is associated with characteristic facial anomalies, generalised arthrogryposis, bony abnormalities, and lung hypoplasia. The skin has a distinctive pathology with compaction of the dermal collagen and fibrosis of the subcutaneous tissue. The inheritance is likely to be autosomal recessive and the condition appears to be fatal in the early neonatal period.

Macular blood flow response to acute reduction of plasma glucose in diabetic patients measured by the blue light entoptic technique

The response of retinal blood flow to acute reduction in plasma glucose levels was studied in 20 poorly controlled type I diabetic patients. Perifoveal flow velocity was determined, using the blue-light entoptoscope, and arterial calibers measured, using a computer-aided digitizing system. Mean plasma glucose level was lowered from 17.7 +/- 4 to 7.0 +/- 1 mmol/l after a subcutaneous insulin infusion and measurements taken at both glucose levels. The autoregulatory change induced by breathing 60% oxygen at the two plasma glucose levels also was compared. Mean flow velocities were 0.54 +/- 0.28 mm/sec at a high plasma glucose level compared with 0.55 +/- 0.32 mm/sec at a low plasma glucose level, whereas hyperoxia reduced these by 16.58 and 16.71%, respectively. No significant difference in the responses of arterial diameters to hyperoxia between the two glucose levels was found. The authors conclude that acute reduction in plasma glucose level in this group of patients is not associated with significant changes in macular blood flow or in alteration in autoregulation.