Autoantibodies against type I IFNs in humans with alternative NF-κB pathway deficiency.

Patients with autoimmune polyendocrinopathy syndrome type 1 (APS-1) caused by autosomal recessive AIRE deficiency produce autoantibodies that neutralize type I interferons (IFNs)1,2, conferring a predisposition to life-threatening COVID-19 pneumonia3. Here we report that patients with autosomal recessive NIK or RELB deficiency, or a specific type of autosomal-dominant NF-κB2 deficiency, also have neutralizing autoantibodies against type I IFNs and are at higher risk of getting life-threatening COVID-19 pneumonia. In patients with autosomal-dominant NF-κB2 deficiency, these autoantibodies are found only in individuals who are heterozygous for variants associated with both transcription (p52 activity) loss of function (LOF) due to impaired p100 processing to generate p52, and regulatory (IκBδ activity) gain of function (GOF) due to the accumulation of unprocessed p100, therefore increasing the inhibitory activity of IκBδ (hereafter, p52LOF/IκBδGOF). By contrast, neutralizing autoantibodies against type I IFNs are not found in individuals who are heterozygous for NFKB2 variants causing haploinsufficiency of p100 and p52 (hereafter, p52LOF/IκBδLOF) or gain-of-function of p52 (hereafter, p52GOF/IκBδLOF). In contrast to patients with APS-1, patients with disorders of NIK, RELB or NF-κB2 have very few tissue-specific autoantibodies. However, their thymuses have an abnormal structure, with few AIRE-expressing medullary thymic epithelial cells. Human inborn errors of the alternative NF-κB pathway impair the development of AIRE-expressing medullary thymic epithelial cells, thereby underlying the production of autoantibodies against type I IFNs and predisposition to viral diseases.

Evaluation of Clinical and Immunological Alterations Associated with ICF Syndrome.

PURPOSE: Immunodeficiency with centromeric instability and facial anomalies (ICF) syndrome is a rare autosomal recessive combined immunodeficiency. The detailed immune responses are not explored widely. We investigated known and novel immune alterations in lymphocyte subpopulations and their association with clinical symptoms in a well-defined ICF cohort. METHODS: We recruited the clinical findings from twelve ICF1 and ICF2 patients. We performed detailed immunological evaluation, including lymphocyte subset analyses, upregulation, and proliferation of T cells. We also determined the frequency of circulating T follicular helper (cTFH) and regulatory T (Treg) cells and their subtypes by flow cytometry. RESULTS: There were ten ICF1 and two ICF2 patients. We identified two novel homozygous missense mutations in the ZBTB24 gene. Respiratory tract infections were the most common recurrent infections among the patients. Gastrointestinal system (GIS) involvements were observed in seven patients. All patients received intravenous immunoglobulin replacement therapy and antibacterial prophylaxis; two died during the follow-up period. Immunologically, CD4+ T-cell counts, percentages of recent thymic emigrant T cells, and naive CD4+ T decreased in two, five, and four patients, respectively. Impaired T-cell proliferation and reduced CD25 upregulation were detected in all patients. These changes were more prominent in CD8+ T cells. GIS involvements negatively correlated with CD3+ T-, CD3+CD4+ T-, CD16+CD56+ NK-cell counts, and CD4+/CD8+ T-cell ratios. Further, we observed expanded cTFH cells and reduced Treg and follicular regulatory T cells with a skewing to a TH2-like phenotype in all tested subpopulations. CONCLUSION: The ICF syndrome encompasses various manifestations affecting multiple end organs. Perturbed T-cell responses with increased cTFH and decreased Treg cells may provide further insight into the immune aberrations observed in ICF syndrome.

Risk factors predisposing children to food allergies.

BACKGROUND: Food allergies are the most common cause of anaphylaxis in children, and their incidence is increasing globally. The aim of this study was to determine the risk factors leading to food allergies in childhood. METHODS: Children with food allergies and non-atopic healthy children were compared using a questionnaire that included prenatal, neonatal, and postnatal risk factors. RESULTS: A total of 314 subjects, 155 patients and 159 healthy children for the control group, were enrolled in the study. The median age of patients with a food allergy at diagnosis was 6 months (1-156 months), and 71 patients (45.8%) were males. The median age of the control group was 12 months (1-61 months), and 67.0% were males. Older maternal age (P = 0.023), birth by caesarean section (P = 0.001), birth in the summer or autumn (P = 0.011), crowded housing (P = 0.001), damp houses (P = 0.001), being fed with breast milk and complementary food (P = 0.001), use of synthetic bedding (P = 0.024), and being the oldest child in the family (P = 0.001) were the considered risk factors for an immunoglobulin-E (IgE)-mediated food allergy. A low frequency of yoghurt consumption by mother (P = 0.001) and use of wool bedding (P = 0.018) were identified as risk factors for non-IgE-mediated food allergies. Low socioeconomic status (P = 0.001) played a protective role against both IgE- and non-IgE-mediated food allergies whereas breastfeeding played a protective role against IgE-mediated food allergies (P = 0.030). CONCLUSION: The most important aspect of this study was that it separately identified prenatal, neonatal, and postnatal risk factors for IgE- and non-IgE-mediated food allergies.

Comparing the levels of CTLA-4-dependent biological defects in patients with LRBA deficiency and CTLA-4 insufficiency.

BACKGROUND: Lipopolysaccharide-responsive beige-like anchor protein (LRBA) deficiency and cytotoxic T-lymphocyte protein-4 (CTLA-4) insufficiency are recently described disorders that present with susceptibility to infections, autoimmunity, and lymphoproliferation. Clinical and immunological comparisons of the diseases with long-term follow-up have not been previously reported. We sought to compare the clinical and laboratory manifestations of both diseases and investigate the role of flow cytometry in predicting the genetic defect in patients with LRBA deficiency and CTLA-4 insufficiency. METHODS: Patients were evaluated clinically with laboratory assessments for lymphocyte subsets, T follicular helper cells (TFH ), LRBA expression, and expression of CD25, FOXP3, and CTLA4 in regulatory T cells (Tregs) at baseline and 16 h post-stimulation. RESULTS: LRBA-deficient patients (n = 29) showed significantly early age of symptom onset, higher rates of pneumonia, autoimmunity, chronic diarrhea, and failure to thrive compared to CTLA-4 insufficiency (n = 12). In total, 29 patients received abatacept with favorable responses and the overall survival probability was not different between transplanted versus non-transplanted patients in LRBA deficiency. Meanwhile, higher probability of survival was observed in CTLA-4-insufficient patients (p = 0.04). The T-cell subsets showed more deviation to memory cells in CTLA-4-insufficiency, accompanied by low percentages of Treg and dysregulated cTFH cells response in both diseases. Cumulative numbers of autoimmunities positively correlated with cTFH frequencies. Baseline CTLA-4 expression was significantly diminished in LRBA deficiency and CTLA-4 insufficiency, but significant induction in CTLA-4 was observed after short-term T-cell stimulation in LRBA deficiency and controls, while this elevation was less in CTLA-4 insufficiency, allowing to differentiate this disease from LRBA deficiency with high sensitivity (87.5%) and specificity (90%). CONCLUSION: This cohort provided detailed clinical and laboratory comparisons for LRBA deficiency and CTLA-4 insufficiency. The flow cytometric approach is useful in predicting the defective gene; thus, targeted sequencing can be conducted to provide rapid diagnosis and treatment for these diseases impacting the CTLA-4 pathway.

Food-induced anaphylaxis in early childhood and factors associated with its severity.

Background: Several factors that increase the risk of severe food-induced anaphylaxis have been identified. Objective: We aimed to determine the demographic, etiologic, and clinical features of food-induced anaphylaxis in early childhood and also any other factors associated with severe anaphylaxis. Methods: We carried out a medical chart review of anaphylaxis cases from 16 pediatric allergy and immunology centers in Turkey. Results: The data of 227 patients with 266 food-induced anaphylaxis episodes were included in the study. The median (interquartile range) age of the first anaphylaxis episode was 9 months (6-18 months); 160 of these patients were boys (70.5%). The anaphylaxis episodes were mild in 75 cases (28.2%), moderate in 154 cases (57.9%), and severe in 37 cases (13.9%). The most frequent food allergens involved were cow's milk (47.4%), nuts (16.7%), and hen's egg (15.8%). Epinephrine was administered in only 98 (36.8%) of these anaphylaxis episodes. A logistic regression analysis revealed two statistically significant factors that were independently associated with severe anaphylaxis: the presence of angioedema and hoarseness during the anaphylactic episode. Urticaria was observed less frequently in patients who developed hypotension. In addition, confusion and syncope were associated with 25.9- and 44.6-fold increases, respectively, in the risk of concomitant hypotension. Conclusion: Cow's milk, nuts, and hen's egg caused the majority of mild and moderate-to-severe anaphylaxis episodes. The presence of angioedema and hoarseness in any patient who presents with a history of food-induced anaphylaxis should alert clinicians that the reaction may be severe. In addition, the presence of confusion, syncope, or stridor probably indicates concomitant hypotension.

Management of subglottic hemangioma with propranolol.

Subglottic hemangioma is a rare but life- threatening condition which requires intervention. It generally starts proliferating in the first and second months of lifespan and whether there is a respiration problem or not, it causes biphasic stridor. Its diagnosis generally requires direct laryngoscopy or direct screening through bronchoscopy. This case report presents a 45-day-old girl who had subglottic hemangioma presenting with wheezing and stridor. Our case took propranolol with a dose of 2 mg/kg/day and within 48 h after the start of the treatment, obstructive symptoms started to alleviate considerably.

Evaluation of red meat allergy patients and review of the literature.

BACKGROUND: It was reported that prevalence of red meat allergy in children was higher in our country than in western populations. However, the diagnosis of these patients is often delayed. The aim of the study was to present the clinical and laboratory characteristics of our red meat allergy patients. METHODS: The data were collected retrospectively from the files of children with red meat allergy. Also, 6 adults with red meat allergies were recorded in the families of the children. Patients with symptoms associated with red meat allergy and sensitive to beef or mutton in prick-to-prick tests were recorded. RESULTS: The median age of the 43 patients was 12 years (2-37), and 51% were male. Most of the patients were children (n=37, 86%). The median age was 10 years in children (2-17), and 54% were male. All of the children had dermatologic manifestations, 51% had respiratory symptoms, and 64% had anaphylaxis upon exposure to red meat. The anaphylaxis history was not associated with demographic, clinical and laboratory data. A total of 63% children had additional allergic diseases, and 75% of them were sensitive to both mutton and beef in prickto- prick tests. The median total IgE level of the children was 327 (20-3550) IU/mL, median eosinophil count was 210/mm < sup > 3 < /sup > (40-990) and mean vitamin D was 13.1 ± 1.2 mcg/L (n=27). Anaphylaxis occurred in 3 of 9 patients who received the open oral food challenge (OFC) test. After OFC, 3 patients continued to eat red meat without issues, and 1 patient was recommended to eat alternatives to red meat. CONCLUSIONS: Clinical and laboratory findings were heterogeneous in children with red meat allergy. Anaphylaxis risk seems to be higher than other food allergies. OFC test is more helpful in both diagnosis and alternative red meat selection compared to laboratory findings.

Multiplex PCR-Based Newborn Screening for Severe T and B-Cell Lymphopenia: The first Pilot Study in Turkey.

Objectives: Severe combined immunodeficiency disease (SCID), non-SCID T-cell lymphopenia, and other primary immunodeficiency diseases with T-cell and B-cell lymphopenia have low the T-cell-receptor-excision circles (TRECs) and κ-deleting-recombination-excision circles (KRECs) levels that can be measured in dried blood spots (DBS) of the newborn. The incidence of SCID and non-SCID T-cell lymphopenia in Western societies has been reported by TREC screening of newborns as 1: 58,000 and 1: 7300, respectively. Since there is no similar study in our country, we aimed to perform the first pilot study of TREC and KREC screening of newborn for SCID and non-SCID T-cell lymphopenia in Turkey. Methods: The heel blood samples of newborns born between 1st October 2015 and 31st December 2016 at two major hospitals in our city were included in this study. TREC and KREC copies were determined by a multiplex quantitative PCR-based method from newborn DBS. Cutoff levels were used as 7 copies per DBS for TRECs and KRECs, 1000 copies for ACTB (internal control). Failed samples or abnormal results in measurements were tested the second time. An immunologist evaluated data of newborns with low TREC and KREC copies clinically and through the laboratory. Results: A total of 1960 DBS were tested. The results of 1856 newborns were evaluated. The low TRECs and/or KRECs levels were detected in 71 newborns (3.8 %). The low TRECs rate was 1.1 %. Preterm newborns have lower levels of TRECs and KRECs than term newborns (both p <0.0001). As a result of immunological research, we did not detect any SCID, but we detected 2 newborns with non-SCID T-cell lymphopenia (1:928). These 2 newborns were found to have frequent and severe infectious diseases or hypogammaglobulinemia in their clinical follow-up, although they did not have absolute lymphopenia. Conclusion: Non-SCID T-cell lymphopenia is common in our country than in western societies. TRECs and KRECs assay should be considered for routine NBS programs in our country. Studies involving more newborns should be conducted to detect SCID.

Impaired respiratory burst contributes to infections in PKCδ-deficient patients.

Patients with autosomal recessive protein kinase C δ (PKCδ) deficiency suffer from childhood-onset autoimmunity, including systemic lupus erythematosus. They also suffer from recurrent infections that overlap with those seen in patients with chronic granulomatous disease (CGD), a disease caused by defects of the phagocyte NADPH oxidase and a lack of reactive oxygen species (ROS) production. We studied an international cohort of 17 PKCδ-deficient patients and found that their EBV-B cells and monocyte-derived phagocytes produced only small amounts of ROS and did not phosphorylate p40phox normally after PMA or opsonized Staphylococcus aureus stimulation. Moreover, the patients' circulating phagocytes displayed abnormally low levels of ROS production and markedly reduced neutrophil extracellular trap formation, altogether suggesting a role for PKCδ in activation of the NADPH oxidase complex. Our findings thus show that patients with PKCδ deficiency have impaired NADPH oxidase activity in various myeloid subsets, which may contribute to their CGD-like infectious phenotype.

Risk factors predisposing children to food allergies

Background: Food allergies are the most common cause of anaphylaxis in children, and their incidence is increasing globally. The aim of this study was to determine the risk factors leading to food allergies in childhood. Methods: Children with food allergies and non-atopic healthy children were compared using a questionnaire that included prenatal, neonatal, and postnatal risk factors. Results: A total of 314 subjects, 155 patients and 159 healthy children for the control group, were enrolled in the study. The median age of patients with a food allergy at diagnosis was 6 months (1–156 months), and 71 patients (45.8%) were males. The median age of the control group was 12 months (1–61 months), and 67.0% were males. Older maternal age (P = 0.023), birth by caesarean section (P = 0.001), birth in the summer or autumn (P = 0.011), crowded housing (P = 0.001), damp houses (P = 0.001), being fed with breast milk and complementary food (P = 0.001), use of synthetic bedding (P = 0.024), and being the oldest child in the family (P = 0.001) were the considered risk factors for an immunoglobulin-E (IgE)-mediated food allergy. A low frequency of yoghurt consumption by mother (P = 0.001) and use of wool bedding (P = 0.018) were identified as risk factors for non-IgE-mediated food allergies. Low socioeconomic status (P = 0.001) played a protective role against both IgE- and non-IgE-mediated food allergies whereas breastfeeding played a protective role against IgE-mediated food allergies (P = 0.030). Conclusion: The most important aspect of this study was that it separately identified prenatal, neonatal, and postnatal risk factors for IgE- and non-IgE-mediated food allergies (AU)