The common variable immunodeficiency IgM repertoire narrowly recognizes erythrocyte and platelet glycans

BACKGROUND

Autoantibody-mediated cytopenias (AICs) regularly occur in profoundly IgG-deficient common variable immunodeficiency (CVID) patients. The isotypes, antigenic targets, and origin(s) of their disease-causing autoantibodies are unclear.

OBJECTIVE

To determine reactivity, clonality and provenance of AIC-associated IgM autoantibodies in CVID patients.

METHODS

We utilized glycan arrays, patient erythrocytes, and platelets to determine targets of CVID IgM autoantibodies. Glycan binding profiles were used to identify auto-reactive clones across B cell subsets, specifically circulating marginal zone-like (MZ) B cells, for sorting and IGH sequencing. The locations, transcriptomes and responses of tonsillar MZ B cells to different T helper cell subsets were determined by confocal microscopy, RNA-sequencing, and co-cultures, respectively.

RESULTS

Autoreactive IgM coated erythrocytes and platelets from many CVID patients with AICs (CVID+AIC). On glycan arrays, CVID+AIC plasma IgM narrowly recognized erythrocytic i antigens and platelet i-related antigens and failed to bind hundreds of pathogen- and tumor-associated carbohydrates. Polyclonal i antigen-recognizing B-cell receptors were highly enriched among CVID+AIC circulating marginal zone (MZ) B cells. Within tonsillar tissues, MZ B cells secreted copious IgM when activated by the combination of IL-10 and IL-21 or when cultured with IL10/IL-21 secreting FOXP3-CD25hiTfh cells. In lymph nodes from immunocompetent controls, MZ B cells, plentiful FOXP3+ regulatory T cells, and rare FOXP3-CD25+ cells that represented likely CD25hiTfh cells, all localized outside of GCs. In CVID+AIC lymph nodes, cellular positions were similar but CD25hiTfh cells greatly outnumbered regulatory cells.

CONCLUSIONS

Our findings indicate glycan-reactive IgM autoantibodies produced outside of GCs may contribute to the autoimmune pathogenesis of CVID.

22q11.2 Deletion-Associated Blood-Brain Barrier Permeability Potentiates Systemic Capillary Leak Syndrome Neurologic Features

We present a case study of a young male with a history of 22q11.2 deletion syndrome (22qDS), diagnosed with systemic capillary leak syndrome (SCLS) who presented with acute onset of diffuse anasarca and sub-comatose obtundation. We hypothesized that his co-presentation of neurological sequelae might be due to blood-brain barrier (BBB) susceptibility conferred by the 22q11.2 deletion, a phenotype that we have previously identified in 22qDS. Using pre- and post-intravenous immunoglobulins (IVIG) patient serum, we studied circulating biomarkers of inflammation and assessed the potential susceptibility of the 22qDS BBB. We employed in vitro cultures of differentiated BBB-like endothelial cells derived from a 22qDS patient and a healthy control. We found evidence of peripheral inflammation and increased serum lipopolysaccharide (LPS) alongside endothelial cells in circulation. We report that the patient's serum significantly impairs barrier function of the 22qDS BBB compared to control. Only two other cases of pediatric SCLS with neurologic symptoms have been reported, and genetic risk factors have been suggested in both instances. As the third case to be reported, our findings are consistent with the hypothesis that genetic susceptibility of the BBB conferred by genes such as claudin-5 deleted in the 22q11.2 region promoted neurologic involvement during SCLS in this patient.

The immunopathological landscape of human pre-TCRα deficiency: From rare to common variants

We describe humans with rare biallelic loss-of-function PTCRA variants impairing pre-α T cell receptor (pre-TCRα) expression. Low circulating naive αβ T cell counts at birth persisted over time, with normal memory αβ and high γδ T cell counts. Their TCRα repertoire was biased, which suggests that noncanonical thymic differentiation pathways can rescue αβ T cell development. Only a minority of these individuals were sick, with infection, lymphoproliferation, and/or autoimmunity. We also report that 1 in 4000 individuals from the Middle East and South Asia are homozygous for a common hypomorphic PTCRA variant. They had normal circulating naive αβ T cell counts but high γδ T cell counts. Although residual pre-TCRα expression drove the differentiation of more αβ T cells, autoimmune conditions were more frequent in these patients compared with the general population.

Immunologic, Molecular, and Clinical Profile of Patients with Chromosome 22q11.2 Duplications

PURPOSE

Duplication of chromosome 22q11.2 due to meiotic non-allelic homologous recombination results in a distinct syndrome, chromosome 22q11.2 duplication syndrome that has some overlapping phenotypic features with the corresponding 22q11.2 deletion syndrome. Literature on immunologic aspects of the duplication syndrome is limited. We conducted a retrospective study of 216 patients with this syndrome to better define the key features of the duplication syndrome.

METHODS

Single-center retrospective record review was performed. Data regarding demographics, clinical details, and immunological tests were compiled, extracted into a predetermined data collection form, and analyzed.

RESULTS

This cohort comprised 113 (52.3%) males and 103 (47.7%) females. The majority (54.6%) of mapped duplications were between low copy repeat regions A-D (LCR22A to -D). Though T cell subsets were relatively preserved, switched memory B cells, immunoglobulins, and specific antibodies were each found to be decreased in a subset of the cohort. One-fifth (17/79, 21.5%) of patients had at least 2 low immunoglobulin values, and panhypogammaglobulinemia was found in 11.7% (9/79) cases. Four children were on regular immunoglobulin replacement therapy. Asthma and eczema were the predominant atopic symptoms in our cohort.

CONCLUSION

Significant immunodeficiencies were observed in our cohort, particularly in B cells and antibodies. Our study expands the current clinical understanding and emphasizes the need of immunological studies and multidisciplinary approaches for these patients.

Disease Progression of WHIM Syndrome in an International Cohort of 66 Pediatric and Adult Patients

Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome (WS) is a combined immunodeficiency caused by gain-of-function mutations in the C-X-C chemokine receptor type 4 (CXCR4) gene. We characterize a unique international cohort of 66 patients, including 57 (86%) cases previously unreported, with variable clinical phenotypes. Of 17 distinct CXCR4 genetic variants within our cohort, 11 were novel pathogenic variants affecting 15 individuals (23%). All variants affect the same CXCR4 region and impair CXCR4 internalization resulting in hyperactive signaling. The median age of diagnosis in our cohort (5.5 years) indicates WHIM syndrome can commonly present in childhood, although some patients are not diagnosed until adulthood. The prevalence and mean age of recognition and/or onset of clinical manifestations within our cohort were infections 88%/1.6 years, neutropenia 98%/3.8 years, lymphopenia 88%/5.0 years, and warts 40%/12.1 years. However, we report greater prevalence and variety of autoimmune complications of WHIM syndrome (21.2%) than reported previously. Patients with versus without family history of WHIM syndrome were diagnosed earlier (22%, average age 1.3 years versus 78%, average age 5 years, respectively). Patients with a family history of WHIM syndrome also received earlier treatment, experienced less hospitalization, and had less end-organ damage. This observation reinforces previous reports that early treatment for WHIM syndrome improves outcomes. Only one patient died; death was attributed to complications of hematopoietic stem cell transplantation. The variable expressivity of WHIM syndrome in pediatric patients delays their diagnosis and therapy. Early-onset bacterial infections with severe neutropenia and/or lymphopenia should prompt genetic testing for WHIM syndrome, even in the absence of warts.

A Toolkit and Framework for Optimal Laboratory Evaluation of Individuals with Suspected Primary Immunodeficiency

Knowledge related to the biology of inborn errors of immunity and associated laboratory testing methods continues to expand at a tremendous rate. Despite this, many patients with inborn errors of immunity suffer for prolonged periods of time before identification of their underlying condition, thereby delaying appropriate care. Understanding that test selection and optimal evaluation for patients with recurrent infections or unusual patterns of inflammation can be unclear, we present a document that distills relevant clinical features of immunologic disease due to inborn errors of immunity and related appropriate and available test options. This document is intended to serve the practicing clinical immunologist and, in turn, patients by describing best available test options for initial and expanded immunologic evaluations across the disease spectrum. Our goal is to demystify the process of evaluating patients with suspected immune dysfunction and to enable more rapid and accurate diagnosis of such individuals.

HEM1 deficiency disrupts mTORC2 and F-actin control in inherited immunodysregulatory disease

Immunodeficiency often coincides with hyperactive immune disorders such as autoimmunity, lymphoproliferation, or atopy, but this coincidence is rarely understood on a molecular level. We describe five patients from four families with immunodeficiency coupled with atopy, lymphoproliferation, and cytokine overproduction harboring mutations in NCKAP1L, which encodes the hematopoietic-specific HEM1 protein. These mutations cause the loss of the HEM1 protein and the WAVE regulatory complex (WRC) or disrupt binding to the WRC regulator, Arf1, thereby impairing actin polymerization, synapse formation, and immune cell migration. Diminished cortical actin networks caused by WRC loss led to uncontrolled cytokine release and immune hyperresponsiveness. HEM1 loss also blocked mechanistic target of rapamycin complex 2 (mTORC2)-dependent AKT phosphorylation, T cell proliferation, and selected effector functions, leading to immunodeficiency. Thus, the evolutionarily conserved HEM1 protein simultaneously regulates filamentous actin (F-actin) and mTORC2 signaling to achieve equipoise in immune responses.

Common variable immunodeficiency-associated endotoxemia promotes early commitment to the T follicular lineage

BACKGROUND

Although chiefly a B-lymphocyte disorder, several research groups have identified common variable immunodeficiency (CVID) subjects with numeric and/or functional T_H cell alterations. The causes, interrelationships, and consequences of CVID-associated CD4⁺ T-cell derangements to hypogammaglobulinemia, autoantibody production, or both remain unclear.

OBJECTIVE

We sought to determine how circulating CD4⁺ T cells are altered in CVID subjects with autoimmune cytopenias (AICs; CVID+AIC) and the causes of these derangements.

METHODS

Using hypothesis-generating, high-dimensional single-cell analyses, we created comprehensive phenotypic maps of circulating CD4⁺ T cells. Differences between subject groups were confirmed in a large and genetically diverse cohort of CVID subjects (n = 69) by using flow cytometry, transcriptional profiling, multiplex cytokine/chemokine detection, and a suite of in vitro functional assays measuring naive T-cell differentiation, B-cell/T-cell cocultures, and regulatory T-cell suppression.

RESULTS

Although CD4⁺ T_H cell profiles from healthy donors and CVID subjects without AICs were virtually indistinguishable, T cells from CVID+AIC subjects exhibited follicular features as early as thymic egress. Follicular skewing correlated with IgA deficiency-associated endotoxemia and endotoxin-induced expression of activin A and inducible T-cell costimulator ligand. The resulting enlarged circulating follicular helper T-cell population from CVID+AIC subjects provided efficient help to receptive healthy donor B cells but not unresponsive CVID B cells. Despite this, circulating follicular helper T cells from CVID+AIC subjects exhibited aberrant transcriptional profiles and altered chemokine/cytokine receptor expression patterns that interfered with regulatory T-cell suppression assays and were associated with autoantibody production.

CONCLUSIONS

Endotoxemia is associated with early commitment to the follicular T-cell lineage in IgA-deficient CVID subjects, particularly those with AICs.

SCID genotype and 6-month posttransplant CD4 count predict survival and immune recovery

The Primary Immune Deficiency Treatment Consortium (PIDTC) performed a retrospective analysis of 662 patients with severe combined immunodeficiency (SCID) who received a hematopoietic cell transplantation (HCT) as first-line treatment between 1982 and 2012 in 33 North American institutions. Overall survival was higher after HCT from matched-sibling donors (MSDs). Among recipients of non-MSD HCT, multivariate analysis showed that the SCID genotype strongly influenced survival and immune reconstitution. Overall survival was similar for patients with RAG, IL2RG, or JAK3 defects and was significantly better compared with patients with ADA or DCLRE1C mutations. Patients with RAG or DCLRE1C mutations had poorer immune reconstitution than other genotypes. Although survival did not correlate with the type of conditioning regimen, recipients of reduced-intensity or myeloablative conditioning had a lower incidence of treatment failure and better T- and B-cell reconstitution, but a higher risk for graft-versus-host disease, compared with those receiving no conditioning or immunosuppression only. Infection-free status and younger age at HCT were associated with improved survival. Typical SCID, leaky SCID, and Omenn syndrome had similar outcomes. Landmark analysis identified CD4+ and CD4+CD45RA+ cell counts at 6 and 12 months post-HCT as biomarkers predictive of overall survival and long-term T-cell reconstitution. Our data emphasize the need for patient-tailored treatment strategies depending upon the underlying SCID genotype. The prognostic significance of CD4+ cell counts as early as 6 months after HCT emphasizes the importance of close follow-up of immune reconstitution to identify patients who may need additional intervention to prevent poor long-term outcome.

Patients with common variable immunodeficiency with autoimmune cytopenias exhibit hyperplastic yet inefficient germinal center responses

BACKGROUND

The lack of pathogen-protective, isotype-switched antibodies in patients with common variable immunodeficiency (CVID) suggests germinal center (GC) hypoplasia, yet a subset of patients with CVID is paradoxically affected by autoantibody-mediated autoimmune cytopenias (AICs) and lymphadenopathy.

OBJECTIVE

We sought to compare the physical characteristics and immunologic output of GC responses in patients with CVID with AIC (CVID+AIC) and without AIC (CVID-AIC).

METHODS

We analyzed GC size and shape in excisional lymph node biopsy specimens from 14 patients with CVID+AIC and 4 patients with CVID-AIC. Using paired peripheral blood samples, we determined how AICs specifically affected B-and T-cell compartments and antibody responses in patients with CVID.

RESULTS

We found that patients with CVID+AIC displayed irregularly shaped hyperplastic GCs, whereas GCs were scarce and small in patients with CVID-AIC. GC hyperplasia was also evidenced by an increase in numbers of circulating follicular helper T cells, which correlated with decreased regulatory T-cell frequencies and function. In addition, patients with CVID+AIC had serum endotoxemia associated with a dearth of isotype-switched memory B cells that displayed significantly lower somatic hypermutation frequencies than their counterparts with CVID-AIC. Moreover, IgG⁺ B cells from patients with CVID+AIC expressed VH4-34-encoded antibodies with unmutated Ala-Val-Tyr and Asn-His-Ser motifs, which recognize both erythrocyte I/i self-antigens and commensal bacteria.

CONCLUSIONS

Patients with CVID+AIC do not contain mucosal microbiota and exhibit hyperplastic yet inefficient GC responses that favor the production of untolerized IgG⁺ B-cell clones that recognize both commensal bacteria and hematopoietic I/i self-antigens.

Smith-Magenis Syndrome Patients Often Display Antibody Deficiency but Not Other Immune Pathologies

BACKGROUND

Smith-Magenis syndrome (SMS) is a complex neurobehavioral disorder associated with recurrent otitis. Most SMS cases result from heterozygous interstitial chromosome 17p11.2 deletions that encompass not only the intellectual disability gene retinoic acid-induced 1 but also other genes associated with immunodeficiency, autoimmunity, and/or malignancy.

OBJECTIVES

The goals of this study were to describe the immunological consequence of 17p11.2 deletions by determining the prevalence of immunological diseases in subjects with SMS and by assessing their immune systems via laboratory methods.

METHODS

We assessed clinical histories of 76 subjects with SMS with heterozygous 17p11.2 deletions and performed in-depth immunological testing on 25 representative cohort members. Laboratory testing included determination of serum antibody concentrations, vaccine titers, and lymphocyte subset frequencies. Detailed reactivity profiles of SMS serum antibodies were performed using custom-made antigen microarrays.

RESULTS

Of 76 subjects with SMS, 74 reported recurrent infections including otitis (88%), pneumonia (47%), sinusitis (42%), and gastroenteritis (34%). Infections were associated with worsening SMS-related neurobehavioral symptoms. The prevalence of autoimmune and atopic diseases was not increased. Malignancy was not reported. Laboratory evaluation revealed most subjects with SMS to be deficient of isotype-switched memory B cells and many to lack protective antipneumococcal antibodies. SMS antibodies were not more reactive than control antibodies to self-antigens.

CONCLUSIONS

Patients with SMS with heterozygous 17p.11.2 deletions display an increased susceptibility to sinopulmonary infections, but not to autoimmune, allergic, or malignant diseases. SMS sera display an antibody reactivity profile favoring neither recognition of pathogen-associated antigens nor self-antigens. Prophylactic strategies to prevent infections may also provide neurobehavioral benefits to selected patients with SMS.

Identification of 22q11.2 Deletion Syndrome via Newborn Screening for Severe Combined Immunodeficiency

PURPOSE

Chromosome 22q11.2 deletion syndrome (22q11.2DS), the most common cause of DiGeorge syndrome, is quite variable. Neonatal diagnosis traditionally relies on recognition of classic features and cytogenetic testing, but many patients come to attention only following identification of later onset conditions, such as hypernasal speech due to palatal insufficiency and developmental and behavioral differences including speech delay, autism, and learning disabilities that would benefit from early interventions. Newborn screening (NBS) for severe combined immunodeficiency (SCID) is now identifying infants with 22q11.2DS due to T cell lymphopenia. Here, we report findings in such neonates, underscoring the efficacy of early diagnosis.

METHODS

A retrospective chart review of 1350 patients with 22q11.2DS evaluated at the Children's Hospital of Philadelphia identified 11 newborns with a positive NBS for SCID.

RESULTS

Five out of 11 would have been diagnosed with 22q11.2DS without NBS, whereas early identification of 22q11.2DS in 6/11 led to the diagnosis of significant associated features including hypocalcemia, congenital heart disease (CHD), and gastroesophageal reflux disease that may have gone unrecognized and therefore untreated.

CONCLUSIONS

Our findings support rapidly screening infants with a positive NBS for SCID, but without SCID, for 22q11.2DS even when typically associated features such as CHD are absent, particularly when B cells and NK cells are normal. Moreover, direct NBS for 22q11.2DS using multiplex qPCR would be equally, if not more, beneficial, as early identification of 22q11.2DS will obviate a protracted diagnostic odyssey while providing an opportunity for timely assessment and interventions as needed, even in the absence of T cell lymphopenia.

Immunodeficiencies Associated with Abnormal Newborn Screening for T Cell and B Cell Lymphopenia

Newborn screening for SCID has revealed the association of low T cells with a number of unexpected syndromes associated with low T cells, some of which were not appreciated to have this feature. This review will discuss diagnostic approaches and the features of some of the syndromes likely to be encountered following newborn screening for immune deficiencies.

Phase I trial of low-dose interleukin 2 therapy in patients with Wiskott-Aldrich syndrome

BACKGROUND

Low dose IL-2 can restore the function of T and NK cells from Wiskott-Aldrich (WAS) patients. However, the safety of in vivo IL-2 in WAS is unknown.

OBJECTIVES

A phase-I study to assess safety of low dose IL-2 in WAS.

METHODS

Patients received 5 daily subcutaneous IL-2 injections, every 2months, for three courses. A "3+3" dose escalation method was used.

RESULTS

6 patients received the 0.5millionunits/m²/day dose without serious adverse events. However, 2 of 3 patients receiving the 1millionunits/m²/day dose developed thrombocytopenia requiring platelet transfusions. A statistically significant platelet increase occurred in patients receiving the 0.5millionunits/m²/day dose. A trend toward higher T, B and NK cell numbers and higher T regulatory cell percentages was observed.

CONCLUSION

We have identified a safe IL-2 dose for WAS patients. Additional trials are indicated to study the efficacy of this immunostimulant as a therapy for WAS.

Mutation in IRF2BP2 is responsible for a familial form of common variable immunodeficiency disorder

BACKGROUND

Genome-wide association studies have shown a pattern of rare copy number variations and single nucleotide polymorphisms in patients with common variable immunodeficiency disorder (CVID), which was recognizable by a support vector machine (SVM) algorithm. However, rare monogenic causes of CVID might lack such a genetic fingerprint.

OBJECTIVE

We sought to identify a unique monogenic cause of familial immunodeficiency and evaluate the use of SVM to identify patients with possible monogenic disorders.

METHODS

A family with multiple members with a diagnosis of CVID was screened by using whole-exome sequencing. The proband and other subjects with mutations associated with CVID-like phenotypes were screened through the SVM algorithm from our recent CVID genome-wide association study. RT-PCR, protein immunoblots, and in vitro plasmablast differentiation assays were performed on patient and control EBV lymphoblastoids cell lines.

RESULTS

Exome sequencing identified a novel heterozygous mutation in IRF2BP2 (c.1652G>A:p.[S551N]) in affected family members. Transduction of the mutant gene into control human B cells decreased production of plasmablasts in vitro, and IRF2BP2 transcripts and protein expression were increased in proband versus control EBV-immortalized lymphoblastoid cell lines. The SVM algorithm categorized the proband and subjects with other immunodeficiency-associated gene variants in TACI, BAFFR, ICOS, CD21, LRBA, and CD27 as genetically dissimilar from polygenic CVID.

CONCLUSION

A novel IRFBP2 mutation was identified in a family with autosomal dominant CVID. Transduction experiments suggest that the mutant protein has an effect on B-cell differentiation and is likely a monogenic cause of the family's CVID phenotype. Successful grouping by the SVM algorithm suggests that our family and other subjects with rare immunodeficiency disorders cluster separately and lack the genetic pattern present in polygenic CVID cases.

Corrigendum: Novel TTC37 Mutations in a Patient with Immunodeficiency without Diarrhea: Extending the Phenotype of Trichohepatoenteric Syndrome

[This corrects the article on p. 2 in vol. 3, PMID: 25688341.].

Novel TTC37 Mutations in a Patient with Immunodeficiency without Diarrhea: Extending the Phenotype of Trichohepatoenteric Syndrome

Unbiased genetic diagnosis has increasingly associated seemingly unrelated somatic and immunological phenotypes. We report a male infant who presented within the first year of life with physical growth impairment, feeding difficulties, hyperemesis without diarrhea, and abnormal hair findings suggestive of trichorrhexis nodosa. With advancing age, moderate global developmental delay, susceptibility to frequent viral illnesses, otitis media, and purulent conjunctivitis were identified. Because of the repeated infections, an immunological evaluation was pursued and identified impaired antibody memory responses following pneumococcal vaccine administration. Immunoglobulin replacement therapy and nutritional support were employed as mainstays of therapy. The child is now aged 12 years and still without diarrhea. Whole exome sequencing identified compound heterozygous mutations in the TTC37 gene, a known cause of the trichohepatoenteric syndrome (THES). This case extends the known phenotype of THES and defines a potential subset for inclusion as an immune overlap syndrome.

Fiscal implications of newborn screening in the diagnosis of severe combined immunodeficiency

In the United States, newborn screening (NBS) is currently recommended for identification of 31 debilitating and potentially fatal conditions. However, individual states determine which of the recommended conditions are screened. The addition of severe combined immunodeficiency (SCID) screening to the recommended NBS panel has been fully instituted by 18 states, with another 11 states piloting programs or planning to begin screening in 2014. Untreated, SCID is uniformly fatal by 2 years of age. Hematopoietic stem cell transplantation usually is curative, but the success rate depends on the age at which the procedure is performed. Short-term implementation costs may be a barrier to adding SCID to states' NBS panels. A retrospective economic analysis was performed to determine the cost-effectiveness of NBS for early (<3.5 months) versus late (≥3.5 months) treatment of children with SCID at 3 centers over 5 years. The mean total charges at these centers for late treatment were 4 times greater than early treatment ($1.43 million vs $365,785, respectively). Mean charges for intensive care treatments were >5 times higher ($350,252 vs $66,379), and operating room-anesthesia charges were approximately 4 times higher ($57,105 vs $15,885). The cost-effectiveness of early treatment for SCID provides a strong economic rationale for the addition of SCID screening to NBS programs of other states.

Invariant natural killer T cells in children with eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is an atopic disease characterized by eosinophilic inflammation in which dietary antigens (in particular, milk) play a major role. EoE is most likely a mixed IgE and non-IgE food-mediated reaction in which overexpression of Th2 cytokines, particularly IL-13, play a major role; however, the cells responsible for IL-13 overexpression remain elusive. Th2-cytokines are secreted following the ligation of invariant natural killer T cell receptors to sphingolipids (SLs). Sphingolipids (SLs) are presented via the CD1d molecule on the INKTs surface. Cow's milk-derived SL has been shown to activate iNKTs from children with IgE-mediated food allergies to milk (FA-MA) to produce Th2 cytokines. The role of iNKTs and milk-SL in EoE pathogenesis is currently unknown.

OBJECTIVE

The aim of this study was to investigate the role of iNKTs and milk-SL in EoE.

METHODS

Peripheral blood mononuclear cells (PBMCs) from 10 children with active EoE (EoE-A), 10 children with controlled EoE (EoE-C) and 16 healthy controls (non-EoE) were measured ex vivo and then incubated with α-galactosylceramide (αGal) and milk-SL. INKTs from peripheral blood (PB) and oesophageal biopsies were studied.

RESULTS

EoE-A children had significantly fewer peripheral blood iNKTs with a greater Th2-response to αGal and milk-SM compared with iNKTs of EoE-C and non-EoE children. Additionally, EoE-A children had increased iNKT levels in oesophageal biopsies compared with EoE-C children.

CONCLUSION

Milk-SLs are able to activate peripheral blood iNKTs in EoE-A children to produce Th2 cytokines. Additionally, iNKT levels are higher at the site of active oesophageal eosinophilic inflammation.

CLINICAL RELEVANCE

This study suggests that sphingolipids (SLs) contained in milk may drive the development of EoE by promoting an iNKT-cell-mediated Th2-type cytokine response that facilitates eosinophil-mediated allergic inflammation.

Transplantation outcomes for severe combined immunodeficiency, 2000-2009

BACKGROUND

The Primary Immune Deficiency Treatment Consortium was formed to analyze the results of hematopoietic-cell transplantation in children with severe combined immunodeficiency (SCID) and other primary immunodeficiencies. Factors associated with a good transplantation outcome need to be identified in order to design safer and more effective curative therapy, particularly for children with SCID diagnosed at birth.

METHODS

We collected data retrospectively from 240 infants with SCID who had received transplants at 25 centers during a 10-year period (2000 through 2009).

RESULTS

Survival at 5 years, freedom from immunoglobulin substitution, and CD3+ T-cell and IgA recovery were more likely among recipients of grafts from matched sibling donors than among recipients of grafts from alternative donors. However, the survival rate was high regardless of donor type among infants who received transplants at 3.5 months of age or younger (94%) and among older infants without prior infection (90%) or with infection that had resolved (82%). Among actively infected infants without a matched sibling donor, survival was best among recipients of haploidentical T-cell-depleted transplants in the absence of any pretransplantation conditioning. Among survivors, reduced-intensity or myeloablative pretransplantation conditioning was associated with an increased likelihood of a CD3+ T-cell count of more than 1000 per cubic millimeter, freedom from immunoglobulin substitution, and IgA recovery but did not significantly affect CD4+ T-cell recovery or recovery of phytohemagglutinin-induced T-cell proliferation. The genetic subtype of SCID affected the quality of CD3+ T-cell recovery but not survival.

CONCLUSIONS

Transplants from donors other than matched siblings were associated with excellent survival among infants with SCID identified before the onset of infection. All available graft sources are expected to lead to excellent survival among asymptomatic infants. (Funded by the National Institute of Allergy and Infectious Diseases and others.).

Cornelia de Lange syndrome: further delineation of phenotype, cohesin biology and educational focus, 5th Biennial Scientific and Educational Symposium abstracts

Cornelia de Lange syndrome (CdLS) is the prototype for the cohesinopathy disorders that have mutations in genes associated with the cohesin subunit in all cells. Roberts syndrome is the next most common cohesinopathy. In addition to the developmental implications of cohesin biology, there is much translational and basic research, with progress towards potential treatment for these conditions. Clinically, there are many issues in CdLS faced by the individual, parents and caretakers, professionals, and schools. The following abstracts are presentations from the 5th Cornelia de Lange Syndrome Scientific and Educational Symposium on June 20-21, 2012, in conjunction with the Cornelia de Lange Syndrome Foundation National Meeting, Lincolnshire, IL. The research committee of the CdLS Foundation organizes the meeting, reviews and accepts abstracts and subsequently disseminates the information to the families. In addition to the basic science and clinical discussions, there were educationally-focused talks related to practical aspects of management at home and in school. AMA CME credits were provided by Greater Baltimore Medical Center, Baltimore, MD.

Immunologic features of Cornelia de Lange syndrome

OBJECTIVES

Cornelia de Lange syndrome (CdLS) is a genetic syndrome with multisystem abnormalities. Infections are a significant cause of morbidity and mortality. The goals of our study were to identify the frequency and types of infections in CdLS and to determine if underlying immunodeficiency contributes to the clinical spectrum of this syndrome.

METHODS

We assessed infectious histories in 45 patients with CdLS and evaluated conventional immunologic screening tests in 27 patients. Among these 27 subjects, additional phenotypic enumeration of T-cell subsets, expression of activation markers in T cells, and production of cytokines in response to T-cell stimulants were studied in 12 CdLS subjects compared with 12 normal case control subjects.

RESULTS

Recurrent infections were reported at high frequency in CdLS patients and included chronic ear infections (53%), chronic viral respiratory infections (46%), pneumonia (42%), sinus infections (33%), oral candidiasis (13%), sepsis (6%), and bacterial skin infections (4%). Full immune evaluation in 27 subjects led to identification of 9 cases of antibody deficiency syndrome in patients with severe forms of CdLS. Subjects with CdLS had decreased percentages of T regulatory cells and T follicular helper cells compared with normal control subjects (P < .05).

CONCLUSIONS

This study identified for the first time a high frequency of antibody deficiency in CdLS subjects, indicating a critical need for screening and management of immunodeficiency in CdLS patients with a history of well-documented severe or recurrent infections. Furthermore, our results indicate that impaired T-cell populations may be associated with antibody deficiency in CdLS.

A patient with X-linked dyskeratosis congenita presenting with bronchiolitis obliterans requiring lung transplantation and immunodeficiency

Dyskeratosis congenita (DKC) is a syndrome characterized by immunodeficiency, bone marrow (BM) failure, somatic abnormalities, and predisposition to malignancy, resulting from mutations in proteins involved in maintenance of telomeres. Pulmonary fibrosis resulting in respiratory failure is a serious complication affecting approximately 20% of DKC patients. Pediatric pulmonologists should consider this diagnosis in patients with lung fibrosis and concurrent immunodeficiency or BM failure.

Chipping away at a mountain: genomic studies in common variable immunodeficiency

Common variable immunodeficiency (CVID) represents one of the most frequently diagnosed disorders of the immune system. Though several causative and associated genes have been identified, the origins of most cases remain unknown. Diagnostic delay is common due to the gradual evolution and wide spectrum of phenotypes, which can include autoimmune disease, enteropathy, and lung disease. A recent genome wide array identified novel gene associations with CVID, and also showed that identification of a genetic signature via a Support Vector Machine algorithm may be a powerful diagnostic tool. Studies utilizing whole genome or exome sequencings have also met with success in identifying new causes of CVID in subgroups of patients.

Autoimmune regulator (AIRE) contributes to Dectin-1-induced TNF-α production and complexes with caspase recruitment domain-containing protein 9 (CARD9), spleen tyrosine kinase (Syk), and Dectin-1

BACKGROUND

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) syndrome is a complex immunologic disease caused by mutation of the autoimmune regulator (AIRE) gene. Autoimmunity in patients with APECED syndrome has been shown to result from deficiency of AIRE function in transcriptional regulation of thymic peripheral tissue antigens, which leads to defective T-cell negative selection. Candidal susceptibility in patients with APECED syndrome is thought to result from aberrant adaptive immunity.

OBJECTIVE

To determine whether AIRE could function in anticandidal innate immune signaling, we investigated an extrathymic role for AIRE in the immune recognition of β-glucan through the Dectin-1 pathway, which is required for defense against Candida species.

METHODS

Innate immune signaling through the Dectin-1 pathway was assessed in both PBMCs from patients with APECED syndrome and a monocytic cell line. Subcellular localization of AIRE was assessed by using confocal microscopy.

RESULTS

PBMCs from patients with APECED syndrome had reduced TNF-α responses after Dectin-1 ligation but in part used a Raf-1-mediated pathway to preserve function. In the THP-1 human monocytic cell line, reducing AIRE expression resulted in significantly decreased TNF-α release after Dectin-1 ligation. AIRE formed a transient complex with the known Dectin-1 pathway components phosphorylated spleen tyrosine kinase and caspase recruitment domain-containing protein 9 after receptor ligation and localized with Dectin-1 at the cell membrane.

CONCLUSION

AIRE can participate in the Dectin-1 signaling pathway, indicating a novel extrathymic role for AIRE and a defect that likely contributes to fungal susceptibility in patients with APECED syndrome.

Dyskeratosis congenita: a combined immunodeficiency with broad clinical spectrum--a single-center pediatric experience

BACKGROUND

Dyskeratosis Congenita (DKC) is a syndrome characterized by immunodeficiency, bone marrow failure, somatic abnormalities, and cancer predisposition resulting from defective telomere maintenance. The immunologic features of DKC remain under diagnosed and under treated despite the fact that immunodeficiency is a major cause of premature mortality in DKC.

METHODS

This study undertook a retrospective review of 7 DKC patients diagnosed at the Children's Hospital of Philadelphia. In parallel, we reviewed previously reported immunologic findings in DKC patients.

RESULTS

Immunologic abnormalities (lymphopenia, low B-cell numbers, hypogammaglobulinemia, and decreased T-cell function) were the most frequent laboratory findings at initial presentation, preceding the development of significant anemia or thrombocytopenia. Recurrent sinopulmonary or opportunistic infections were present in 6/7 patients. Infant-onset patients had more severe immunologic and somatic features (particularly severe enteropathy).

CONCLUSION

In DKC, development of immunologic abnormalities can precede bone marrow failure, highlighting the importance of proper immunodeficiency management to minimize morbidity and premature mortality in this disease.

Invariant natural killer T cells from children with versus without food allergy exhibit differential responsiveness to milk-derived sphingomyelin

BACKGROUND

A key immunologic feature of food allergy (FA) is the presence of a T(h)2-type cytokine bias. Ligation of the invariant natural killer T cell (iNKT) T-cell receptor (TCR) by sphingolipids presented via the CD1d molecule leads to copious secretion of T(h)2-type cytokines. Major food allergens (eg, milk, egg) are the richest dietary source of sphingolipids (food-derived sphingolipids [food-SLs]). Nonetheless, the role of iNKTs in FA is unknown.

OBJECTIVE

To investigate the role of iNKTs in FA and to assess whether food-SL-CD1d complexes can engage the iNKT-TCR and induce iNKT functions.

METHODS

PBMCs from 15 children with cow's milk allergy (MA), 12 children tolerant to cow's milk but with allergy to egg, and 13 healthy controls were incubated with α-galactosylceramide (αGal), cow's milk-sphingomyelin, or hen's egg-ceramide. iNKTs were quantified, and their cytokine production and proliferation were assessed. Human CD1d tetramers loaded with milk-sphingomyelin or egg-ceramide were used to determine food-SL binding to the iNKT-TCR.

RESULTS

Milk-sphingomyelin, but not egg-ceramide, can engage the iNKT-TCR and induce iNKT proliferation and T(h)2-type cytokine secretion. Children with FA, especially those with MA, had significantly fewer peripheral blood iNKTs and their iNKTs exhibited a greater T(h)2 response to αGal and milk-sphingomyelin than iNKTs of healthy controls.

CONCLUSION

iNKTs from children with FA, especially those with MA, are reduced in number and exhibit a T(h)2 bias in response to αGal and milk-sphingomyelin. These data suggest a potential role for iNKTs in FA.

Association of eosinophilic gastrointestinal disorders with other atopic disorders

Eosinophilic esophagitis is a chronic disease that leads to either persistent symptoms or, at times, intermittent "flares." It shares many features with other atopic diseases (asthma, allergic rhinitis, and atopic dermatitis), including the following: T helper 2 cells and eosinophils play a critical role in the pathogenesis of the disease; avoidance of allergens promotes remission of disease and symptom control; and locally applied corticosteroids provide control. Finally, most patients who have eosinophilic gastrointestinal disorders have an associated atopic disease.

CHARGE (coloboma, heart defect, atresia choanae, retarded growth and development, genital hypoplasia, ear anomalies/deafness) syndrome and chromosome 22q11.2 deletion syndrome: a comparison of immunologic and nonimmunologic phenotypic features

OBJECTIVES

CHARGE (coloboma, heart defect, atresia choanae, retarded growth and development, genital hypoplasia, ear anomalies/deafness) syndrome and chromosome 22q11.2 deletion syndrome are known to have significant clinical overlap including cardiac anomalies, ear abnormalities, hearing loss, developmental delay, renal abnormalities, and cleft palate. Immunodeficiency has been well documented in 22q11.2 deletion, but there has been limited recognition of this potentially serious complication in CHARGE syndrome. The goals of our study were to identify clinical features unique to CHARGE syndrome or 22q11.2 deletion and to describe the spectrum of immunodeficiency found in patients with CHARGE syndrome.

METHODS

This study included 25 children diagnosed with CHARGE syndrome with positive CHD7 mutations through the Children's Hospital of Philadelphia genetics program. Clinical features and laboratory findings were reviewed retrospectively. We compared our findings to data available for a large cohort of patients with 22q11.2 deletion syndrome followed in our clinical genetics program.

RESULTS

Features found more commonly in CHARGE syndrome included coloboma, choanal atresia, facial nerve palsy, tracheoesophageal fistula, and genital hypoplasia in boys. A high incidence of marked hypocalcemia was observed in our study group (72%). We found a spectrum of cell-mediated immunodeficiency in our study group, which ranged from lymphopenia (60%) to severe combined immunodeficiency (8%). Defects in humoral immunity were documented in 4 patients and included severe hypogammaglobulinemia with decreased T-cell numbers, transient hypogammaglobulinemia during infancy, and immunoglobulin A deficiency.

CONCLUSIONS

The presence of coloboma, choanal atresia, facial nerve palsy, tracheoesophageal fistula, or genital hypoplasia in boys should alert the clinician to the possibility of CHARGE syndrome rather than the 22q11.2 deletion. Molecular testing for CHD7 mutations may help to confirm the diagnosis. In this study, significant hypocalcemia and lymphopenia occurred more frequently in patients with CHARGE syndrome than in those with 22q11.2 deletion syndrome. Early inclusion of immunologists to the multidisciplinary care team (as with 22q11.2 deletion) may be of great benefit to affected patients.