222 Rn emanation measurements for the XENON1T experiment.

The selection of low-radioactive construction materials is of utmost importance for the success of low-energy rare event search experiments. Besides radioactive contaminants in the bulk, the emanation of radioactive radon atoms from material surfaces attains increasing relevance in the effort to further reduce the background of such experiments. In this work, we present the 222 Rn emanation measurements performed for the XENON1T dark matter experiment. Together with the bulk impurity screening campaign, the results enabled us to select the radio-purest construction materials, targeting a 222 Rn activity concentration of 10 µ Bq / kg in 3.2 t of xenon. The knowledge of the distribution of the 222 Rn sources allowed us to selectively eliminate problematic components in the course of the experiment. The predictions from the emanation measurements were compared to data of the 222 Rn activity concentration in XENON1T. The final 222 Rn activity concentration of ( 4.5 ± 0.1 ) µ Bq / kg in the target of XENON1T is the lowest ever achieved in a xenon dark matter experiment.

Light Dark Matter Search with Ionization Signals in XENON1T.

We report constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment. We mitigate backgrounds with strong event selections, rather than requiring a scintillation signal, leaving an effective exposure of (22±3) tonne day. Above ∼0.4 keV_{ee}, we observe <1 event/(tonne day keV_{ee}), which is more than 1000 times lower than in similar searches with other detectors. Despite observing a higher rate at lower energies, no DM or CEvNS detection may be claimed because we cannot model all of our backgrounds. We thus exclude new regions in the parameter spaces for DM-nucleus scattering for DM masses m_{χ} within 3-6 GeV/c^{2}, DM-electron scattering for m_{χ}>30 MeV/c^{2}, and absorption of dark photons and axionlike particles for m_{χ} within 0.186-1 keV/c^{2}.

Search for Light Dark Matter Interactions Enhanced by the Migdal Effect or Bremsstrahlung in XENON1T.

Direct dark matter detection experiments based on a liquid xenon target are leading the search for dark matter particles with masses above ∼5 GeV/c^{2}, but have limited sensitivity to lighter masses because of the small momentum transfer in dark matter-nucleus elastic scattering. However, there is an irreducible contribution from inelastic processes accompanying the elastic scattering, which leads to the excitation and ionization of the recoiling atom (the Migdal effect) or the emission of a bremsstrahlung photon. In this Letter, we report on a probe of low-mass dark matter with masses down to about 85 MeV/c^{2} by looking for electronic recoils induced by the Migdal effect and bremsstrahlung using data from the XENON1T experiment. Besides the approach of detecting both scintillation and ionization signals, we exploit an approach that uses ionization signals only, which allows for a lower detection threshold. This analysis significantly enhances the sensitivity of XENON1T to light dark matter previously beyond its reach.

Flow cytometric analysis of TCR Vß repertoire in patients with 22q11.2 deletion syndrome.

In 22q11.2 deletion patients, the normal decrease in T lymphocyte counts after 1-2 years is blunted such that relatively T lymphocyte numbers increase over early childhood, probably via post-thymic expansion of peripheral lymphocytes. This may leave less T lymphocyte receptor (TCR) diversity than when derived from naive thymic emigrants. We analysed TCR Vß repertoire on 27 22q11.2 chromosome deletion patients. No patient had infection at sampling. CD3(+) CD4(+) recent thymic emigrants (RTEs) were identified by CD45RA and CD31 expression. TCR Vß repertoire was determined using four-colour flow cytometry. Patients and controls showed significant TCR Vß family usage differences between CD3(+) CD4(+) and CD3(+) CD4(-) T lymphocyte subpopulations. Vß family abnormalities (±3 SD of controls) were identified in 18/27 (67%) patients and 12/47 (25%) controls. In patients, the magnitude of expansions was increased, with some Vß families representing 37% of the cells present in the subpopulations. There was a significant increase in frequency of abnormalities in CD3(+) CD4(+) (P < 0.001) and CD3(+) CD4(-) T lymphocytes (P < 0.05) in patients. A total of 11/16 patients had an abnormal CD4(+) CD25(Bright) TCR Vß repertoire. There was no difference in expansions/contractions between CD4(+) CD25(Bright) and CD4(+) T lymphocyte repertoires (P = 0.575) for individual patients but significant differences in expansions/contractions between CD4(+) CD25(Bright) and CD8(+) T lymphocytes repertoires (P = 0.011). There was bias in Vß usage between CD3(+) CD4(+) and CD3(+) CD4(-) T lymphocyte subsets. A total of 67% patients had TCR Vß repertoire abnormalities, with a trend towards increased repertoire abnormalities with fewer RTEs, suggesting thymic output plays an important role in TCR repertoire diversity. There was no correlation between skewed repertoire and symptoms of infection or autoimmunity.

Intrasinus catheter-directed heparin infusion in the treatment of dural venous sinus thrombosis.

BACKGROUND AND PURPOSE: In this small series, local intrasinus catheter-directed heparin infusion with or without balloon thrombectomy was safe in the treatment of dural venous sinus thrombosis (DVST). Although systemic anticoagulation (SAC) is the treatment of choice, there is a lack of consensus regarding the best treatment should SAC fail or be contraindicated. We present our institutional experience with 16 patients in whom failure of, or contraindication to, SAC occurred and who subsequently underwent intrasinus catheter-directed heparin infusion with or without balloon thrombectomy. MATERIALS AND METHODS: A retrospective review of 16 patients ranging in age from 14 days to 77 years who had intrasinus catheter-directed heparin infusion was undertaken with 9 male and 7 female patients identified. Of these 16 patients, 4 (25%) had a contraindication to SAC and SAC failed in 12 (75%). Technically successful intrasinus infusion catheter placement was achieved in all 16 patients (100%). Mean duration of infusion was 3.3 days (range, 1-6 days). Adjunctive balloon thrombectomy was performed in 9 (56.3%) of 16 patients. No procedure-related mortality occurred. RESULTS: Partial and complete sinus recanalization occurred in 10 (62.5%) of 16 patients and 1 (6.3%) of 16 patients, respectively. There were 3 deaths (18.8%) attributed to disease progression. At most recent clinical follow-up (mean, 9.3 months), 11 (84.6%) of 13 surviving patients were independent, with a modified Rankin Scale (mRS) score of 1 or less. CONCLUSIONS: Local intrasinus catheter-directed heparin infusion with or without adjunctive balloon thrombectomy seems to be a safe and effective treatment of DVST in patients in whom SAC failed or in whom there was a contraindication to SAC. In addition, the risk for symptomatic intracranial hemorrhage may be significantly lower than intrasinus infusion of thrombolytics.

Sphenoidal electrode placement using biplane fluoroscopy and rotational flat panel CT imaging.

Assessment of otherwise occult seizure foci arising from the anterior mesial temporal region occasionally necessitates placement of sphenoidal electrodes (SEs). This minimally invasive procedure is often performed without imaging guidance; however, more precise lead positioning with a reduced risk of complications has been described with fluoroscopic guidance. We describe the added value of rotational flat panel CT imaging for precise anatomic localization of the SE tip in relation to the foramen ovale.

Mutations in CHD7 in patients with CHARGE syndrome cause T-B + natural killer cell + severe combined immune deficiency and may cause Omenn-like syndrome.

More than 11 genetic causes of severe combined immunodeficiency (SCID) have been identified, affecting development and/or function of T lymphocytes, and sometimes B lymphocytes and natural killer (NK) cells. Deletion of 22q11.2 is associated with immunodeficiency, although less than 1% of cases are associated with T-B + NK + SCID phenotype. Severe immunodeficiency with CHARGE syndrome has been noted only rarely Omenn syndrome is a rare autosomal recessive form of SCID with erythroderma, hepatosplenomegaly, lymphadenopathy and alopecia. Hypomorphic recombination activating genes 1 and 2 mutations were first described in patients with Omenn syndrome. More recently, defects in Artemis, RMRP, IL7Ralpha and common gamma chain genes have been described. We describe four patients with mutations in CHD7, who had clinical features of CHARGE syndrome and who had T-B + NK + SCID (two patients) or clinical features consistent with Omenn syndrome (two patients). Immunodeficiency in patients with DiGeorge syndrome is well recognized--CHARGE syndrome should now be added to the causes of T-B + NK + SCID, and mutations in the CHD7 gene may be associated with Omenn-like syndrome.

T cell receptor Vbeta repertoire of T lymphocytes and T regulatory cells by flow cytometric analysis in healthy children.

Evaluation of the T cell receptor (TCR) Vbeta repertoire by flow cytometric analysis has been used for studying the T cell compartments for diseases in which T cells are implicated in the pathogenesis. For the interpretation of these studies information is needed about Vbeta usage in healthy individuals and there are few data for normal usage in paediatric populations. We examined the T lymphocyte (sub)populations in 47 healthy controls (age range: 3 months-16 years). We found non-random Vbeta usage with skewed reactivity of some families towards CD4+ or CD4- T cells. Importantly, there appeared to be no significant change in Vbeta usage according to age group. Some controls showed expansions in some Vbeta families, although incidence of such expansions was low. We went on to examine the repertoire of CD4+CD25(Bright) T regulatory cells in 25 healthy controls. We found overlapping quantitative usage for each of the Vbeta families between CD4+CD25- and CD4+CD25(Bright) T cells. However, there was a significant preferential usage for five Vbeta families and decreased usage of two Vbeta families in the CD4+CD25(Bright) T cells, suggesting that although they overlap there may be subtle but important differences in the TCR repertoire of T regulatory cells.

Postmortem diagnosis of chronic granulomatous disease: how worthwhile is it?

A previously healthy 11 year old boy died unexpectedly after a rapid course of progressive pneumonia. Postmortem microbiology and histopathology suggested an underlying diagnosis of chronic granulomatous disease. This was confirmed by neutrophil oxidative burst and gene mutation analysis of other family members, one of whom benefited from early bone marrow transplantation.

Single centre experience of umbilical cord stem cell transplantation for primary immunodeficiency.

Primary immunodeficiencies (PID) are an important cause of childhood mortality. Haematopoietic stem cell transplantation (HSCT) is the best treatment for many PID. Umbilical cord stem cells are an alternative source of HSC. There is little data regarding outcome of umbilical cord stem cell transplantation (UCSCT) for PID. Our single centre experience is reported. A retrospective study of 14 of 148 patients transplanted for PID, who have received 15 UCSCT was performed, with specific regard to graft-versus-host disease (GvHD) and immune reconstitution. Eight patients with severe combined immunodeficiency (SCID), and six with other combined immunodeficiencies were treated. Of the patients, 12 received unrelated cords, and two had sibling transplants. Median age at transplant was 3.5 months, median nucleated cell dose was 0.8 x 10(8)/kg. All engrafted. Median time to neutrophil engraftment was 22 days, median time to platelet engraftment was 51 days. One developed significant grade III GvHD post transplantation. In total, 11 patients had full donor T and six full donor B-cell chimerism, six of nine patients >1 year post-BMT had normal IgG levels and specific antibody responses to tetanus and Hib vaccines; two are being assessed. Two patients died of multi-organ failure related to pre-existing infection and inflammatory complications respectively. UCSCT should be considered for patients requiring stem cell therapy for PID.

Lymphocyte subsets in term and significantly preterm UK infants in the first year of life analysed by single platform flow cytometry.

This observational study describes the ranges observed for lymphocyte subsets for significantly preterm infants (<32 weeks) in the first year of life, measured by single platform flow cytometry and compared to identically determined subsets in term infants. After ethical approval 39 term and 28 preterm infants had lymphocyte subset analysis before and after their primary immunization series. Median values with 5th and 95th percentiles of absolute counts and percentages are presented for total lymphocytes, T cells, NK cells, B cells, cytotoxic T cells, helper T cells, dual positive T cells, activated T cells, activated T helper cells (including T regulatory cells), pan memory T cells, pan naive T cells, memory helper T cells, naive helper T cells and the T helper/suppressor ratio. The lymphocyte profile of the preterm infants differed from that of the term infants.

The clinical and biological overlap between Nijmegen Breakage Syndrome and Fanconi anemia.

Fanconi anemia (FA), an autosomal recessive chromosomal instability syndrome, is characterized clinically by developmental abnormalities, growth retardation, progressive bone marrow failure, pancytopenia, and pronounced cancer predisposition. Nijmegen Breakage Syndrome (NBS) is a related disorder that shares overlapping clinical features, principally, developmental delay, microcephaly, and cancer predisposition. The diagnosis has relied on chromosomal instability following exposure to DNA cross-linking agents in FA and to ionizing radiation (IR) in NBS. We describe two patients who clinically had FA, but showed sensitivity to both DNA cross-linking agents and ionizing radiation, and who were found to have a rare mutation in the NBS gene. The importance of genetic diagnosis with respect to treatment and prognosis is discussed.

Successful umbilical cord blood stem cell transplantation for chronic granulomatous disease.

Chronic granulomatous disease (CGD) causes growth failure, inflammatory lung damage and often early death. Prophylactic cotrimoxazole improves medium-term survival, but cannot prevent inflammatory sequelae. We report the first patient with CGD who underwent successful HLA identical sibling umbilical cord stem cell transplantation (UCSCT) after myeloablative conditioning. The patient presented with colitis, confirmed as CGD at 2 years of age. Following BU16/CY200 conditioning, he had UCSCT from his unaffected HLA identical sister. A year post-transplant, his colitis had resolved clinically and on radioisotope scan growth has improved. Neutrophil oxidative burst was 92% normal with full donor lymphocyte reconstitution.

Antibody deficiency and autoimmunity in 22q11.2 deletion syndrome.

BACKGROUND: Although severe T cell immunodeficiency in DiGeorge anomaly is rare, previous studies of humoral function in these patients have found no antibody abnormalities but have not examined the response to polysaccharide antigens. Isolated cases of autoimmunity have been reported. Several patients with 22q11.2 deletion attending our immunology clinic suffered recurrent sinopulmonary infection or autoimmune phenomena. AIMS: To investigate humoral immunodeficiency, particularly pneumococcal polysaccharide antibody deficiency, and autoimmune phenomena in a cohort of patients with 22q11.2 deletion. METHODS: A history of severe or recurrent infection and autoimmune symptoms were noted. Lymphocyte subsets, immunoglobulins, IgG subclasses, specific vaccine antibodies, and autoantibodies were measured. Subjects were vaccinated with appropriate antigens as indicated. RESULTS: Of 32 patients identified, 26 (81%) had severe or recurrent infection, of which 13 (50%) had abnormal serum immunoglobulin measurements and 11/20 >/=4 years old (55%) had an abnormal response to pneumococcal polysaccharide. Ten of 30 patients (33%) had autoimmune phenomena; six (20%) were symptomatic. CONCLUSIONS: Humoral immunodeficiency is more common than previously recognised in patients with 22q11.2 deletion. Normal T cell function and immunoglobulin levels do not exclude poor specific antibody responses. Patients should be referred for formal immunological assessment of cellular and humoral immune function.

Lymphocyte subset populations in children with polysaccharide antibody deficiency following cardiac transplantation.

Pneumococcal polysaccharide (PPS) antibody deficiency occurs in some children immunosuppressed following cardiac transplantation in early childhood. We studied lymphocyte subset populations in these children to identify patterns associated with antibody deficiency, particularly in CD21 + B cells. Lymphocyte surface markers CD3, CD4, CD8, CD19, and CD21 were measured on whole blood by FACS analysis in four patient groups: cardiac transplant patients who did and did not respond to PPS, nontransplanted cardiac patients, and normal controls. Absolute cell numbers were compared with age-related normal ranges. The proportion of children with values below the age-related 25th percentile in each group was compared. Normal controls had significantly more CD3+, CD8+, and CD19+ cells, even when age-related differences were accounted for. Control groups had significantly more CD19 cells than transplant patients and transplanted PPS responders and cardiac controls had more mature B cells (CD21+) than transplanted PPS nonresponders. PPS antibody deficiency following pediatric cardiac transplantation may be related to an immaturity in B cells due to immunosuppression commenced in early childhood.

CAMPATH-1M T-cell depleted BMT for SCID: long-term follow-up of 19 children treated 1987-98 in a single center.

BACKGROUND: SCID can be cured by BMT. Depletion of mature T cells from BM has enabled HLA non-identical stem-cell transplantation. We report the outcome of 30 patients treated with 37 T-cell depleted BMT procedures using CAMPATH-1M in vitro between 1987-98 in a single center. METHODS: Immune reconstitution and quality-of-life were assessed in 19 longterm survivors. All but two received pre-transplant conditioning. T- and B-cell chimerism, numbers and function were analyzed during a median follow-up of 5.3 years (range 1.33-12). RESULTS: The overall engraftment rate was 59%, six children required repeated BMT and the survival rate was 63%. All have donor T cells, 58% normal T-cell numbers and 74% normal T-cell function. Of 17 evaluated, 16 patients (94%) have normal IgM and IgG levels, and production of specific Abs to protein Ags, but only 5/16 (31%) have a good response to pneumococcal polysaccharide. Early and late post-BMT complications were rare and there were no delayed deaths. Only one child continues on long-term i.v. Ig 4-years post-BMT. Eleven children died (37%). DISCUSSION: CAMPATH-1M T-cell depleted BMT for SCID resulted in 63% survival. Deaths of 11 children were mainly due to pre-existing infections. Seventeen of 19 long-term survivors have normal immune function and good quality-of-life.

Delayed engraftment and mixed chimerism after HLA-identical sibling donor BMT in Fanconi anaemia.

A 12-year-old girl with Fanconi anaemia (FA) received a bone marrow transplant from her HLA-identical brother following conditioning with cyclophosphamide (20 mg/kg), thoraco-abdominal radiation (TAI) (4 Gy) and equine anti-thymocyte globulin (ATG) (90 mg/kg). Engraftment was delayed and initially tenuous, and was followed by mixed chimerism (MC) over a follow-up period of 2 years. DNA analysis of engraftment was performed on whole peripheral blood and on separated granulocytes, B and T lymphocytes using PCR detection of CA tandem repeat polymorphisms. At 10 weeks post BMT, granulocytes were predominantly donor, but B and T lymphocytes recipient, in origin. Over the subsequent 90 weeks, granulocytes and B lymphocytes were donor-derived, whilst T cells showed persistent MC but with an increasing donor component. Marrow haemopoietic function (Hb, ANC and platelet count) improved gradually in parallel with a rise in the proportion of donor lymphocyte engraftment. We postulate that a population of recipient lymphocytes survived conditioning and in turn delayed the development of full donor chimerism. Although transient MC has been described after allogeneic BMT in FA, its association with delayed engraftment, and persistence for more than 1 year post BMT, has not been documented clearly.