Reference ranges for serum immunoglobulin (IgG, IgA, and IgM) and IgG subclass levels in healthy children

Biomarkers for a less invasive strategy to predict children with eosinophilic esophagitis

BACKGROUND

Noninvasive biomarkers for diagnosing and monitoring eosinophilic esophagitis (EoE) are currently lacking. This study evaluates 20 biomarkers in serum and saliva, aiming to assess their diagnostic potential in pediatric EoE patients and healthy individuals.

METHODS

Blood and saliva from children undergoing upper endoscopy were analyzed for biomarkers, including absolute eosinophil count (AEC), eosinophil-derived neurotoxin (EDN), total and specific IgG4-antibodies (sIgG4), specific IgE-antibodies (sIgE) and 15-hydroxyeicosatetraenoic acid (15(S)-HETE). Some patients participated twice, forming a longitudinal cohort. The ability to use the biomarkers to predict the EoE diagnosis was evaluated.

RESULTS

Analysis from 105 children divided into active EoE, remission, and healthy, revealed elevated levels of serum biomarkers (AEC, EDN, 15(S)-HETE, sIgG4, and sIgE) in active EoE compared to healthy individuals. A combination of biomarkers (AEC, EDN, sIgE to egg white and wheat) and symptoms showed an AUC of 0.92 in distinguishing between the three groups. We further showed that optimal cutoff values for these biomarkers could discriminate between active EoE and healthy with a sensitivity of 88% and a specificity of 100% in distinguishing EoE (active and in remission) from healthy. Longitudinally, levels of EDN, sIgG4 to Bos d 4, Bos d 5, Bos d 8, gliadin, and birch, and sIgE to milk decreased in patients progressing from active EoE to remission (p <.05).

CONCLUSIONS

This study identified novel biomarkers associated with EoE and proposes a panel, together with symptoms, for effective discrimination between active EoE, EoE in remission, and healthy individuals. The findings may contribute to a less invasive diagnostic method and may be a potential surveillance tool for pediatric EoE patients.

Immunoglobulin therapies for primary immunodeficiency diseases (part 1): understanding the pharmacokinetics

Immunoglobulin G (IgG) therapies have been used for decades as standard treatment for patients with primary antibody deficiencies. Monitoring the pharmacokinetics (PK) of IgG is a key component in guiding treatment regimens. Despite the wealth of clinical experience, substantial gaps exist in our understanding of the true nature of IgGs and their disposition in humans. Furthermore, intrinsic and extrinsic factors may alter the PK of IgG, necessitating an individualized approach for patients. A comprehensive literature review was performed in order to summarize the PK of IgGs, examine the mechanisms of IgG disposition (including catabolism), outline considerations for special patient populations and discuss knowledge gaps and future perspectives for improving our understanding of IgG PK in relation to the individualized treatment paradigm.

Preexisting antibody assays for gene therapy: Considerations on patient selection cutoffs and companion diagnostic requirements

Recombinant adeno-associated virus (AAV) vectors are the leading delivery vehicle used for in vivo gene therapies. Anti-AAV antibodies (AAV Abs) can interact with the viral capsid component of an AAV-based gene therapy (GT). Therefore, patients with preexisting AAV Abs (seropositive patients) are often excluded from GT trials to prevent treatment of patients who are unlikely to benefit1 or may have a higher risk for adverse events outweighing treatment benefits. On the contrary, unnecessary exclusion of patients with high unmet medical need should be avoided. Instead, a risk-benefit assessment that weighs the potential risks due to seropositivity vs. severity of disease and available treatment options, should drive the decision if patient selection is required. Assays for patient selection must be validated according to their intended use following national regulations/standards for diagnostic assays in appropriate laboratories. In this review, we summarize the current process of patient selection, including assay cutoff criteria and related assay validation approaches. We further provide considerations on regulatory requirements for the development of in vitro diagnostic tests supporting market authorization of a corresponding GT.

Disturbances in the IgG Antibody Profile in HIV-Exposed Uninfected Infants Associated with Maternal Factors

Over the last 20 years, the incidence of vertical HIV transmission has decreased from 25%-42% to less than 1%. Although there are no signs of infection, the health of HIV-exposed uninfected (HEU) infants is notoriously affected during the first months of life, with opportunistic infections being the most common disease. Some studies have reported effects on the vertical transfer of antibodies, but little is known about the subclass distribution of these antibodies. We proposed to evaluate the total IgG concentration and its subclasses in HIV+ mothers and HEU pairs and to determine which maternal factors condition their levels. In this study, plasma from 69 HEU newborns, their mothers, and 71 control pairs was quantified via immunoassays for each IgG isotype. Furthermore, we followed the antibody profile of HEUs throughout the first year of life. We showed that mothers present an antibody profile characterized by high concentrations of IgG1 and IgG3 but reduced IgG2, and HEU infants are born with an IgG subclass profile similar to that of their maternal pair. Interestingly, this passively transferred profile could remain influenced even during their own antibody production in HEU infants, depending on maternal conditions such as CD4+ T-cell counts and maternal antiretroviral treatment. Our findings indicate that HEU infants exhibit an altered IgG subclass profile influenced by maternal factors, potentially contributing to their increased susceptibility to infections.

Diagnostic accuracy of a novel point-of-care test for simultaneous detection of anti-transglutaminase IgA and anti-deamidated gliadin IgG antibodies

BACKGROUND

Point-of-care tests (POCTs) may have a role in detecting undiagnosed cases of Celiac disease (CD). We assessed the diagnostic accuracy of a novel POCT, compared with the conventional serological methods, for simultaneous anti-transglutaminase (tTG) IgA and anti-deamidated gliadin (DGP) IgG antibody detection. Furthermore, we evaluated the effect of different biological matrices (whole blood and serum) on test performance.

METHODS

Serum and whole blood from celiac or suspected celiac patients who underwent duodenal biopsy were assayed for the presence of anti-tTG IgA and anti-DGP IgG both with the reference standard methods (Thermo Fisher Scientific, Uppsala, Sweden) and with the POCT (PRIMA Lab SA, Balerna, Switzerland).

RESULTS

266 sera (101 negative and 165 positive) and 60 whole blood samples (34 positive and 26 negative) were included in the study. POCT for anti-DGP IgG showed a sensitivity of 84.3% and a specificity of 90.1%, with positive (PPV) and negative predictive values (NPV) of 91.07% and 82.73%. POCT for anti-tTG IgA showed a sensitivity of 98.31% and a specificity of 98.02%, with a PPV and NPV of 98.31% and 98.02%. Test accuracies were 86.94% and 98.17%, respectively. The agreement of the results between the two different matrices showed a strong correlation rate: 95% for anti-DGP IgG and 100% for anti-tTG IgA.

CONCLUSION

The anti-tTG IgA/anti-DGP IgG-based POCT showed good diagnostic accuracy with comparable sensitivities and specificities to reference standard methods in detecting CD in symptomatic patients and could be considered as a mass screening test before referring to conventional serology.

Mulibrey nanism and immunological complications: a comprehensive case report and literature review

Introduction

Mulibrey nanism (MUL) is a rare disorder caused by TRIM37 gene variants characterized by growth failure, dysmorphic features, congestive heart failure (CHF), and an increased risk of Wilms' tumor. Although immune system impairment has been documented in MUL, the underlying mechanisms remain poorly understood.

Methods

We present a case of MUL with progressive lymphopenia and review similar cases from the literature.

Results

Our patient presented with prenatal onset growth restriction, characteristic dysmorphic features, and Wilms' tumor. She developed progressive lymphopenia starting at 10 years of age, leading to the initiation of intravenous immunoglobulin (IVIG) replacement therapy and infection prophylaxis. Genetic analysis detected a likely pathogenic variant on the maternal allele and copy number loss on the paternal allele in TRIM37. Subsequently a cardiac magnetic resonance imaging was conducted revealing signs of pericardial constriction raising concerns for intestinal lymphatic losses. The cessation of IVIG therapy did not coincide with any increase in the rate of infections. The patient exhibited a distinct immunological profile, characterized by hypogammaglobulinemia, impaired antibody responses, and skewed T-cell subsets with an altered CD4+/CD8+ ratio, consistent with previous reports. Normal thymocyte development assessed by artificial thymic organoid platform ruled out an early hematopoietic intrinsic defect of T-cell development.

Discussion

The immunological profile of MUL patients reported so far shares similarities with that described in protein-losing enteropathy secondary to CHF in Fontan circulation and primary intestinal lymphangiectasia. These similarities include hypogammaglobulinemia, significant T-cell deficiency with decreased CD4+ and CD8+ counts, altered CD4+/CD8+ ratios, and significantly modified CD4+ and CD8+ T-cell phenotypes toward effector and terminal differentiated T cells, accompanied by a loss of naïve CD45RA+ T lymphocytes. In MUL, CHF is a cardinal feature, occurring in a significant proportion of patients and influencing prognosis. Signs of CHF or constrictive pericarditis have been evident in the case reported here and in all cases of MUL with documented immune dysfunction reported so far. These observations raise intriguing connections between these conditions. However, further investigation is warranted to in-depth define the immunological defect, providing valuable insights into the pathophysiology and treatment strategies for this condition.

The opposing effects of two gene defects in STX11 and SLP76 on the disease in a patient with an inborn error of immunity

BACKGROUND

Inborn errors of immunity are mostly monogenic. However, disease phenotype and outcome may be modified by the coexistence of a second gene defect.

OBJECTIVE

We sought to identify the genetic basis of the disease in a patient who experienced bleeding episodes, pancytopenia, hepatosplenomegaly, and recurrent pneumonia that resulted in death.

METHODS

Genetic analysis was done using next-generation sequencing. Protein expression and phosphorylation were determined by immunoblotting. T-cell proliferation and F-actin levels were studied by flow cytometry.

RESULTS

The patient harbored 2 homozygous deletions in STX11 (c.369_370del, c.374_376del; p.V124fs60∗) previously associated with familial hemophagocytic lymphohistiocytosis and a novel homozygous missense variant in SLP76 (c.767C>T; p.T256I) that resulted in an approximately 85% decrease in SLP76 levels and absent T-cell proliferation. The patient's heterozygous family members showed an approximately 50% decrease in SLP76 levels but normal immune function. SLP76-deficient J14 Jurkat cells did not express SLP76 and had decreased extracellular signal-regulated kinase signaling, basal F-actin levels, and polymerization following T-cell receptor stimulation. Reconstitution of J14 cells with T256I mutant SLP76 resulted in low protein expression and abnormal extracellular signal-regulated kinase phosphorylation and F-actin polymerization after T-cell receptor activation compared with normal expression and J14 function when wild-type SLP76 was introduced.

CONCLUSIONS

The hypomorphic mutation in SLP76 tones down the hyperinflammation due to STX11 deletion, resulting in a combined immunodeficiency that overshadows the hemophagocytic lymphohistiocytosis phenotype. To our knowledge, this study represents the first report of the opposing effects of 2 gene defects on the disease in a patient with an inborn error of immunity.

Circulation of Respiratory Viruses in the City: Towards an Agent-Based Ecosystem model

Mathematical models play an important role in management of outbreaks of acute respiratory infections (ARI). While such models are generally used to study the spread of a solitary virus, in reality multiple viruses co-circulate in the population. These viruses have been studied in detail, including the course of infection and immune defense mechanisms. We developed an agent-based model, called ABM-ARI, assimilating heterogeneous data and theoretical knowledge into a biologically motivated system, that allows to reproduce the seasonal patterns of ARI incidence and simulate interventions. ABM-ARI uses city-specific data to create a synthetic population and to construct realistic contact networks in different activity settings. Characteristics of infection, immune protection and non-specific resistance were varied between individuals to account for the population heterogeneity. For the calibration, we minimised the normalised mean absolute error between simulated and observed epidemic curves. ABM-ARI was built based on the quantitative assessment of features of predominant respiratory viruses and epidemiological characteristics of the population. It provides a good fit to the observed epidemic curves for different age groups and viruses. We also simulated one-week school closures when student absences were at or above 10%, 20% or 30% and found that only 10% and 20% thresholds resulted in a reduction of the incidence. ABM-ARI has a great potential in tackling the challenge of emerging infections by simulating and evaluating the effectiveness of various interventions.

Reference intervals for serum immunoglobulin A levels in Brazilian children aged 1 to 10 years: a population-based study

OBJECTIVE

To determine reference intervals (RI) for serum immunoglobulin A (IgA) levels in healthy children aged 1 to 1 0 years residing in the central region of Brazil.

METHODS

This cross-sectional study was conducted on 1,743 healthy children randomly selected from kindergartens and public schools in Cuiabá, MT, Brazil. The IgA RIs were defined using the statistical methods postulated by the guidelines of the United States Clinical and Laboratory Standards Institute, the nonparametric bootstrap method, and Horn's robust method after the correction of discrepancies by Tukey's, Dixon's, and Horn's methods, respectively. The results were defined based on the values contained between the 2.5th and 97.5th percentiles and their respective 95% confidence intervals.

RESULTS

Partition by sex was not necessary to determine the IgA RI of the studied children. Homogeneous subgroups were identified among children aged 1-<2, 2-<5, and 5-<11 years, whose IgA-specific RIs were determined.

CONCLUSION

The serum IgA RIs were established for three groups of Brazilian children aged 1-11 years, which differed from those currently applied in Brazilian pediatric practice and from those defined by international studies. This definition will help Brazilian pediatricians formulate an accurate diagnosis and facilitate decision-making.

Serum immunoglobulin A (IgA) levels in children affected with Juvenile Idiopathic Arthritis

Background and objective

Immunoglobulin A (IgA) is the most abundant antibody isotype in the human body, considering its presence on the mucosal surfaces, in addition to the amount circulating in the bloodstream. Serum IgA levels can be variably altered in several pathological settings. However, very few studies specifically investigated serum IgA in Juvenile Idiopathic Arthritis (JIA). In the present study, we specifically assessed serum IgA levels in our cohort of patients affected with JIA.

Methods

In this cross-sectional study, serum IgA levels were measured in patients with JIA (and age-matched controls) and analyzed according to age class. The correlation of serum IgA levels with hematological, inflammatory, and disease activity parameters was assessed.

Results

No significant difference in the frequency of low IgA levels (according to the definition of complete and partial IgA deficiency) was observed between JIA patients and controls, overall. This pediatric study population showed a progressive increase of total serum IgA concentrations with age, as expected; however, in JIA patients aged 10-17 years, total IgA serum levels resulted to be significantly higher than in age-matched control subjects. No clear correlation between IgA levels and the examined inflammatory, hematological, and disease activity parameters was observed in JIA patients, except for the erythrocyte sedimentation rate (ESR) in oligoarticular JIA patients: here, serum IgA levels showed a positive and moderate covariation with ESR, which was also observed for disease activity (JADAS-10) in selected oJIA patients without biological therapy.

Conclusions

In our cohort of JIA patients, total serum IgA levels were not reduced and were actually increased in adolescents compared to controls. Larger studies are needed to confirm this finding, which cannot be certainly explained based on the available data in this study, even though JIA disease control and/or chronic inflammation may be implicated to some extent.

Effects of Diabetes and Voluntary Exercise on IgA Concentration and Polymeric Immunoglobulin Receptor Expression in the Submandibular Gland of Rats

Background and Objectives: Patients with diabetes are more susceptible to upper respiratory tract infections (URTIs) because they are easily infected. Salivary IgA (sali-IgA) levels play a major role in transmitting URTIs. Sali-IgA levels are determined by salivary gland IgA production and polymeric immunoglobulin receptor (poly-IgR) expression. However, it is unknown whether salivary gland IgA production and poly-IgR expression are decreased in patients with diabetes. While exercise is reported to increase or decrease the sali-IgA levels, it is unclear how exercise affects the salivary glands of patients with diabetes. This study aimed to determine the effects of diabetes and voluntary exercise on IgA production and poly-IgR expression in the salivary glands of diabetic rats. Materials and Methods: Ten spontaneously diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats (eight-week-old) were divided into two groups of five rats each: a non-exercise group (OLETF-C) and a voluntary wheel-running group (OLETF-E). Five Long-Evans Tokushima Otsuka (LETO) rats without diabetes were bred under the same conditions as the OLETF-C. Sixteen weeks after the study began, the submandibular glands (SGs) were collected and analyzed for IgA and poly-IgR expression levels. Results: IgA concentrations and poly-IgR expression levels in SGs were lower in OLETF-C and OLETF-E than in LETO (p < 0.05). These values did not differ between the OLETF-C and OLETF-E. Conclusions: Diabetes decreases IgA production and poly-IgR expression in the salivary glands of rats. Moreover, voluntary exercise increases sali-IgA levels but does not increase IgA production and poly-IgR expression in the salivary glands of diabetic rats. Increasing IgA production and poly-IgR expression in the salivary glands, which is reduced in diabetes, might require slightly higher-intensity exercise than voluntary exercise under the supervision of a doctor.

L-cysteine/MoS2 modified robust surface plasmon resonance optical fiber sensor for sensing of Ferritin and IgG

L-cysteine conjugated molybdenum disulphide (MoS₂) nanosheets have been covalently attached to a gold coated surface plasmon resonance (SPR) optical fiber to prepare a robust and stable sensor. Owing to the multifunctionality of the deposited nanosheet conjugate, the antibodies are also covalently conjugated in the subsequent step to realize the design of a SPR optical fiber biosensor for the two important bioanalytes namely, Ferritin and Immunoglobin G (IgG). The different stages of the biosensor preparation have been characterized and verified with microscopic and spectroscopic techniques. A uniform and stable deposition of the L-cysteine/MoS₂ nanosheets has allowed the biosensor to be reused for multiple times. Unlike the peeling-off of the MoS₂ coatings from the gold layer reported previously in the case of physically adsorbed nanomaterial, the herein adopted strategy addresses this critical concern. It has also been possible to use the single SPR fiber for both Ferritin and IgG bioassay experiments by regenerating the sensor and immobilizing two different antibodies in separate steps. For ferritin, the biosensor has delivered a linear sensor response (SPR wavelength shifts) in the concentration range of 50-400 ng/mL, while IgG has been successfully sensed from 50 to 250 µg/mL. The limit of detection for Ferritin and IgG analysis have been estimated to be 12 ng/mL and 7.2 µg/mL, respectively. The biosensors have also been verified for their specificity for the targeted molecule only. A uniform and stable deposition of the nanomaterial conjugate, reproducibility, regeneration capacity, a good sensitivity, and the specificity can be highlighted as some of key features of the L-cysteine/MoS₂ optical fiber biosensor. The system can be advocated as a useful biosensor setup for the sensitive biosensing of Ferritin and IgG.

Urinary epidermal growth factor predicts complete remission of proteinuria in Chinese children with IgA nephropathy

BACKGROUND

This study investigated the association between urinary epidermal growth factor (EGF) and complete remission (CR) of proteinuria in children with IgA nephropathy (IgAN).

METHODS

We included 108 patients from the Registry of IgA Nephropathy in Chinese Children. The urinary EGF at the baseline and follow-up were measured and normalized by urine creatinine (expressed as uEGF/Cr). The person-specific uEGF/Cr slopes were estimated using linear mixed-effects models for the subset of patients with longitudinal data of uEGF/Cr. Cox models were used to analyze the associations of baseline uEGF/Cr and uEGF/Cr slope with CR of proteinuria.

RESULTS

Patients with high baseline uEGF/Cr were more likely to achieve CR of proteinuria (adjusted HR 2.24, 95% CI: 1.05-4.79). The addition of high baseline uEGF/Cr on the traditional parameters significantly improved the model fit for predicting CR of proteinuria. In the subset of patients with longitudinal data of uEGF/Cr, high uEGF/Cr slope was associated with a higher likelihood of CR of proteinuria (adjusted HR 4.03, 95% CI: 1.02-15.88).

CONCLUSIONS

Urinary EGF may be a useful noninvasive biomarker for predicting and monitoring CR of proteinuria in children with IgAN.

IMPACT

High levels of baseline uEGF/Cr (>21.45 ng/mg) could serve as an independent predictor for CR of proteinuria. The addition of baseline uEGF/Cr on the traditional clinical pathological parameters significantly improved the fitting ability for the prediction of CR of proteinuria. Longitudinal data of uEGF/Cr were also independently associated with CR of proteinuria. Our study provides evidence that urinary EGF may be a useful noninvasive biomarker in the prediction of CR of proteinuria as well as monitoring therapeutic response, thus guiding treatment strategies in clinical practice for children with IgAN.

Impact of nitric oxide synthesis modulators on the state of humoral immune system in experimental antiphospholipid syndrome

Background: Antiphospholipid syndrome is an autoimmune disease of multiple venous and/or arterial thrombosis and/or pregnancy loss. Oxidative stress only enhances the body’s immune response. In pathological conditions, the formation of nitric oxide is disrupted, which can be manifested by vasoconstriction, increased coagulation, and endothelial dysfunction.

Objective: The aim of the research was to study the level of immunoglobulins and circulating immune complexes (CICs) in experimental antiphospholipid syndrome and its correction with L-arginine and aminoguanidine.

Materials and methods: Antiphospholipid syndrome was modeled on white female BALB/c mice. L-arginine (25 mg/kg) and aminoguanidine (10 mg/kg) were used for its correction. The content of immunoglobulins and CICs was studied.

Results: It was established that the level of immunoglobulins (Ig) and circulating immune complexes increased in the group of animals with antiphospholipid syndrome compare to the control. The levels of IgA and CICs decreased significantly, and the levels of IgM and IgG did not change in the mice with antiphospholipid syndrome and L-arginine correction. In cases of aminoguanidine administration, decreased IgM and IgG levels and no significant decrease in IgA and CICs was evidenced compare to the animals with antiphospholipid syndrome. In cases of using a combination of L-arginine and aminoguanidine agents, only IgM did not change, all other parameters decreased compare to the animals with APS.

Conclusion: The parameters of the humoral immunity in female mice with experimental antiphospholipid syndrome increase. The level of immunoglobulins and circulating immune complexes decrease depending on the chosen correction agents or their complex administration. Thus, L-arginine and aminoguanidine has a positive effect on various immunity responses by decreasing the negative impact of pathobiochemical alterations.

Correlation Depending on Age Between Saliva and Plasma Parameters

Introduction. Because of the increasing interest in the study of saliva, many methods have become available that can allow us to perform multiple and rapid analyzes of the composition of salivary secretion using advanced techniques of nanotechnology and fluid micro- engineering. The objectives of our study were to identify immunoglobulin levels variations with age.

Materials and methods. We conducted an analysis to check the correlation between saliva and plasma parameters on 24 patients. The study population was divided into 2 groups based on age, with a cut-off at 35 years. The differences on the variables between two groups were evaluated by TTEST and CORREL.

Results. Total plasma calcium, as well as ionic calcium have increased values in group 2, the increase being statistically significant (p =0.04) only for ionic calcium. Significant correlation of plasma and salivary values in the case of IgA / IgG ratio, and also a significant correlation of salivary and plasma concentrations for IgG were identified in our study.

Conclusions. The correlation between plasma and salivary parameters is closely related to age and these can be used as markers for diagnosis and evaluation of various pathologies. Also, regarding women, salivary calcium and phosphate concentrations increase with age showing peak values around menopause.

Neonatal sepsis and transient immunodeficiency: Potential for novel immunoglobulin therapies?

Neonates, especially preterm neonates, have the highest risk of sepsis of all age groups. Transient immaturity of the neonatal immune system is an important risk factor. Neonates suffer from hypogammaglobulinemia as nor IgA nor IgM is transferred over the placenta and IgG is only transferred over the placenta late in gestation. In addition, neutrophil numbers and complement function are also decreased. This mini-review focuses on strategies to improve neonatal host-defense. Both clinical and preclinical studies have attempted to boost neonatal immunity to lower the incidence of sepsis and improve outcome. Recent advances in the development of (monoclonal) antibodies show promising results in preclinical studies but have yet to be tested in clinical trials. Strategies to increase complement activity seem efficient in vitro but potential disadvantages such as hyperinflammation have held back further clinical development. Increase of neutrophil numbers has been tested extensively in clinical trials but failed to show improvement in mortality. Future research should focus on clinical applicability of promising new prevention strategies for neonatal sepsis.

Spondyloenchondrodysplasia Due to Mutation in ACP5 Gene Presenting with Nephrotic Syndrome: A Case Report

Spondyloenchondrodysplasia (SPENCD) with immune dysregulation (SPENCDI) is a rare autosomal recessive inherited immuno-osseous dysplasia characterized by spondylo-metaphyseal enchondromas, along with immune dysregulation ranging from immunodeficiency to autoimmune disorder. Here, we present two cousins with ACP5 gene mutation who had severe short stature with mild hypogammaglobulinemia, nephrotic syndrome, autoimmune thyroiditis and cerebral calcification (Case 1); and in the other (Case 2), there was no clinical findings other than severe short stature, CD4+−T cell lymphopenia and non-autoimmune compensated hypothyroidism. We wanted to emphasize that monogenic causes should be considered in the etiology of early-onset nephrotic syndrome due to the detection of a mutation in the ACP5 gene (her actual diagnosis was changed to SPENCDI.) 5 years after the diagnosis of nephrotic syndrome in the first case, and that the renal involvement may occur without SLE in patients with ACP5 mutation. Severe short stature was a common finding in both cases. We underlined that the clinic can be different even in the same mutation, due to the absence of cerebral calcification and renal involvement in the second case, which is a cousin with Case 1. As a result, endocrinologists, immunologists, rheumatologists, nephrologists and orthopedists should be aware of this syndrome, because SPENCDI causes a pleiotropic (due to more than one phenotypic effect of a gene) clinical picture. Severe short stature may be the only presenting sign of patients with SPENCDI. In addition, in the presence of early-onset nephrotic syndrome and autoimmune thyroiditis, the patient should be evaluated for this type of monogenic disorders as well.

Mycophenolate mofetil-induced hypogammaglobulinemia and infectious disease susceptibility in pediatric patients with chronic rheumatic disorders: a monocentric retrospective study

Mycophenolate mofetil (MMF) is an immunosuppressive drug used for the treatment of autoimmune rheumatological diseases. To test the risk of hypothetical drug-induced hypogammaglobulinemia, the aim of this study was to report the trend of the immunoglobulin (Ig) values and of the infectious diseases in children treated with MMF. This study retrospectively evaluated demographic, clinical, and laboratory data of a cohort of patients affected by a chronic rheumatic disease receiving MMF, followed at the Rheumatology Unit of Meyer Children Hospital, Florence. A total of 29 pediatric patients were enrolled. In patients with normal values of immunoglobulins at the baseline, treatment with MMF resulted in a statistically significant reduction of the IgG levels (p = 0.0058) and in a decrease of IgM levels not reaching statistical significance. The levels of IgA were not affected. During the follow-up, seven patients developed an humoral immune defect. The univariate analysis did not identify any risk factors related to the iatrogenic hypogammaglobulinemia. The infection rate during MMF therapy was significantly higher than the 12-month period before therapy (p = 0.006), while the severe infections did not significantly increase (p = 0.1818), even considering only the patients with hypogammaglobulinemia.

CONCLUSION

In pediatric patients with chronic rheumatic diseases, immunological first level tests and serological analyses to screen the protection against the common childhood pathogens are suggested before starting an immunosuppressive drug. These patients should also complete the vaccination schedule. In patients treated with MMF a strict monitoring of Ig is required during treatment and after discontinuation of the drug.

WHAT IS KNOWN

• MMF is an immunosuppressive drug initially used for the treatment of the graft-versus-host disease. • Mycophenolic acid is an inhibitor of inosine-5'-monophosphate dehydrogenase, expressed in lymphocytes; therefore, MMF could impair the immune system function.

WHAT IS NEW

• MMF resulted in a reduction of IgG and an increase of not severe infection rate. • Immunological first level tests, including Ig, lymphocyte subpopulations, and antibody response to vaccines, are suggested in pediatric patients before starting MMF; a strict monitoring of Ig is important before, during, and after MMF treatment.

Clinical report and predictors of sequelae of 319 cases of pediatric bacterial osteomyelitis

Pediatric osteomyelitis is an insidious disease that can lead to permanent sequelae, the management of which still relies on lengthy intravenous antibiotic therapy. The purpose of this study is to report and describe the clinical course and outcome of pediatric bacterial osteomyelitis in our experience. We reported the clinical, diagnostic, and treatment characteristics of all cases of osteomyelitis in children younger than 18 years of age who were hospitalized between January 2010 and December 2021 at the Bambino Gesù Children’s Hospital in Rome, Italy, we compared patients with and without complications at follow-up, to identify any predictive factor for sequelae. The study sample included 319 cases of pediatric bacterial osteomyelitis. The median age was 7.77 years. Males (60.8%) were more affected than females. The most affected bones were the femur, tibia, and spine. Etiology was identified in 40.1% of cases, with S.aureus as the most common causative agent. Sequelae were reported in 43 cases (13.5%). The main predictors of sequelae were sepsis on admission and hypergammaglobulinemia. Our results show that a severe presentation with sepsis and hypergammaglobulinemia on admission may be associated with a higher frequency of late sequelae. Early recognition and aggressive treatment of this subgroup of patients may lead to a reduction in complications.

Natural history of type 1 diabetes on an immunodysregulatory background with genetic alteration in B-cell activating factor receptor: A case report

The immunological events leading to type 1 diabetes (T1D) are complex and heterogeneous, underscoring the necessity to study rare cases to improve our understanding. Here, we report the case of a 16-year-old patient who showed glycosuria during a regular checkup. Upon further evaluation, stage 2 T1D, autoimmune thrombocytopenic purpura (AITP), and common variable immunodeficiency (CVID) were diagnosed. The patient underwent low carb diet, losing > 8 kg, and was placed on Ig replacement therapy. Anti-CD20 monoclonal antibody (Rituximab, RTX) was administered 2 years after diagnosis to treat peripheral polyneuropathy, whereas an atypical mycobacteriosis manifested 4 years after diagnosis and was managed with prolonged antibiotic treatment. In the fifth year of monitoring, the patient progressed to insulin dependency despite ZnT8A autoantibody resolution and IA-2A and GADA autoantibody decline. The patient had low T1D genetic risk score (GRS = 0.22817) and absence of human leukocyte antigen (HLA) DR3/DR4-DQ8. Genetic analysis identified the monoallelic mutation H159Y in TNFRSF13C, a gene encoding B-cell activating factor receptor (BAFFR). Significant reduced blood B-cell numbers and BAFFR levels were observed in line with a dysregulation in BAFF–BAFFR signaling. The elevated frequency of PD-1⁺ dysfunctional Tfh cells composed predominantly by Th1 phenotype was observed at disease onset and during follow-up. This case report describes a patient progressing to T1D on a BAFFR-mediated immunodysregulatory background, suggesting a role of BAFF–BAFFR signaling in islet-specific tolerance and T1D progression.

Monoclonal antibodies effectively potentiate complement activation and phagocytosis of Staphylococcus epidermidis in neonatal human plasma

Central line associated bloodstream infections (CLABSI) with Staphylococcus epidermidis are a major cause of morbidity in neonates, who have an increased risk of infection because of their immature immune system. As especially preterm neonates suffer from antibody deficiency, clinical studies into preventive therapies have thus far focused on antibody supplementation with pooled intravenous immunoglobulins from healthy donors (IVIG) but with little success. Here we study the potential of monoclonal antibodies (mAbs) against S. epidermidis to induce phagocytic killing by human neutrophils. Nine different mAbs recognizing Staphylococcal surface components were cloned and expressed as human IgG1s. In binding assays, clones rF1, CR5133 and CR6453 showed the strongest binding to S. epidermidis ATCC14990 and CR5133 and CR6453 bound the majority of clinical isolates from neonatal sepsis (19 out of 20). To study the immune-activating potential of rF1, CR5133 and CR6453, bacteria were opsonized with mAbs in the presence or absence of complement. We observed that activation of the complement system is essential to induce efficient phagocytosis of S. epidermidis. Complement activation and phagocytic killing could be enhanced by Fc-mutations that improve IgG1 hexamerization on cellular surfaces. Finally, we studied the ability of the mAbs to activate complement in r-Hirudin neonatal plasma conditions. We show that classical pathway complement activity in plasma isolated from neonatal cord blood is comparable to adult levels. Furthermore, mAbs could greatly enhance phagocytosis of S. epidermidis in neonatal plasma. Altogether, our findings provide insights that are crucial for optimizing anti-S. epidermidis mAbs as prophylactic agents for neonatal CLABSI.

Congenital Rare Diseases Causing Persistent Diarrhea in the Newborn: A Single Center Experience

Congenital diarrheal disorders (CDDs) are a heterogeneous group of inherited diseases that typically occur in the first weeks of life or can present later in life after the introduction of different nutrients; they can cause life-threatening severe dehydration and electrolyte disturbances. This study was conducted to characterize the causes of monogenic CDDs, and their clinical consequences. Clinical characteristics of 31 patients with CDDs that occurred in the first month of life and lasted more than 2 weeks were analyzed retrospectively. The patients were divided into groups according to the current CDD classification. The rate of consanguinity among parents was 77.4%. Of the patients, 16 (51.6%) were female and 15 (48.4%) were male. The underlying genetic defect was determined in 26 (83.9%) patients. The most common etiologic factors were digestive disorders of food and absorption and transport of electrolytes (58.1%, 18/31) (most of them being carbohydrate malabsorption disorders, 12/18) and intestinal immune system disorders (9.6%, 3/31). Total parenteral nutrition (TPN) was given to 45.2% (14/31) of the patients. Mortality rate was 28.5% (8/28). In conclusion, early diagnosis and treatment of CDDs with high morbidity and mortality is extremely important in terms of prognosis. Clinical and laboratory findings, stool characteristics, histopathological findings and the effects of dietary therapy are the primary and most important steps that lead to accurate diagnosis. In addition, advanced diagnostic possibilities, including genetic analyses, are essential for diagnosing underlying diseases.

The Mutation of CD27 Deficiency Presented With Familial Hodgkin Lymphoma and a Review of the Literature

This study aimed to report 4 siblings with CD27 deficiency presented with Hodgkin lymphoma. The father of the family, his 2 wives, and 17 children born from these wives were included into the study. CD27 mutation of all the family members with, and without Hodgkin lymphoma were studied. The variants detected by the exome sequencing analysis were verified by Sanger sequencing and analyzed using SeqScape Software 3. It was determined that both the father of the family and his 2 wives carried the same variant heterozygously. Of the children born to the first mother, 2 children were normal, 3 were heterozygous and 5 were homozygous. Four of these 5 homozygous children were diagnosed with Hodgkin lymphoma. Of the children born to the second mother, 1 child was normal, 3 children were heterozygous and 2 children were homozygous, and none of them had developed a malignant event. We also showed that CD27 deficiency may enhance Treg differentiation. According to our information, this study augmented the relationship of Hodgkin lymphoma and CD27 deficiency. The detection of homozygous CD27 variant in all siblings who developed lymphoma strengthened the place of this mutation in the etiology of Hodgkin lymphoma. In contrast, the presence of homozygous siblings with no malignant event suggested the possible contributions of environmental factors on the etiology.

Toxocariasis in migrant children: A 6 years' experience in a reference pediatric unit in Spain

BACKGROUND

Toxocariasis is a worldwide distributed zoonosis that affects characteristically children. Clinical presentation is highly variable, often asymptomatic, and treatment duration is controversial.

METHODS

A retrospective descriptive study (January 2014-December 2019) was performed in a referral Unit for Pediatric Tropical Diseases. Patients younger than 18 years of age diagnosed with toxocariasis were included.

RESULTS

Out of 931 children screened for toxocariasis, 49 (5.3%) were seropositive. The median age was 11.0 years, 55.1% male and 30.6% referred contact with puppies. Overall, 34.7% were Latin-American, 24.5% Asiatic, 20.4% European, and 20.4% African. Only 34.7% presented symptoms, gastrointestinal the most common (52.9%). The 57.1% of children presented eosinophilia and 50% elevated total IgE. Most cases (95.9%) corresponded to covert toxocariasis. All children were treated with albendazole for 5-14-21 days, and 4 children required a second course. Follow-up data were available in 32 children (65.3%) for a median of 7 months, showing a progressive decline in eosinophils, IgE-titers and ELISA optical density.

CONCLUSION

Toxocariasis is mostly asymptomatic in children and eosinophilia is not always present. Serological tests should be included in migrant health screening and in the diagnostic assessment of eosinophilia. Eosinophil count, IgE-titers and ELISA optical-density could be useful during follow-up.

Acquired Thrombotic Thrombocytopenic Purpura in a 5-Year-old Child With Wiskott-Aldrich Syndrome

Thrombocytopenia is often seen as a laboratory finding during childhood. A supposed idiopathic thrombocytopenic purpura patient who was later diagnosed as Wiskott-Aldrich syndrome (WAS) and developed acquired thrombotic thrombocytopenic purpura (aTTP). Although autoimmune manifestations in WAS described, aTTP was reported just once. Five-year-old-boy was initially brought with cough, bloody stool (diarrhea), oral mucosal bleeding at 12th months of age. Following diagnosed with idiopathic thrombocytopenic purpura and receiving intravenous immunoglobulin, platelet count raised from 20,000 to 50,000/µL. One year after WAS diagnosis by mutation analysis, he presented with complaints of resistant fever, epistaxis, and melena. Hemoglobin decreased from 10 to 5.9 g/dL. Schistocytes in peripheral blood smear and high anti-ADAMTS-13 antibody level indicated development of aTTP.

Eosinophilia in Migrant Children: How Should We Proceed?

BACKGROUND

The diagnostic approach to eosinophilia is complex, given the numerous reported etiologies. Intestinal parasites (especially helminths) are a concern in children from high-burden settings. We describe the diagnostic approach and clinical management of eosinophilia in a cohort of migrant children.

METHODS

We conducted a retrospective observational study that included children diagnosed with eosinophilia at a reference center for pediatric tropical diseases from 2014 to 2018. All patients were screened according to a unified protocol, including direct microbiologic and serologic tests.

RESULTS

A total of 163 children presented with eosinophilia during the study period [median age, 7.7 years (4.1-12.2); 57.1% boys], mostly from Asia (27.6%) and South America (22.1%). Most were internationally adopted children (43.6%) or migrants (26.4%). Only 34.4% of the children were symptomatic, and the main etiology for eosinophilia was helminths (56.4%). After a sequential diagnostic approach, no etiology was found for 40.5% of the patients. The independent risk factors for an unexplained etiology were younger age (≤2 years: odds ratio, 3.6; 95% CI, 1.3-10.2; P = 0.015), absence of symptoms (odds ratio, 4.8; 95% CI, 1.8-12.5; P = 0.001) and mild eosinophilia (<1000/µL: odds ratio, 4.2; 95% CI, 4.5-11.7; P = 0.005). Only 6 children were treated empirically. In those children with an identified cause and in those treated empirically, the eosinophilia resolved in 52% in a median of 7 months (5-9).

CONCLUSIONS

Helminths are the main cause of eosinophilia in migrant children and need to be hunted, especially in older children with eosinophil counts >1000 eosinophils/µL.

Effects of 8 Weeks of High-Intensity Interval Training and Spirulina Supplementation on Immunoglobin Levels, Cardio-Respiratory Fitness, and Body Composition of Overweight and Obese Women

Simple Summary

Overweight and obese, like other forms of malnutrition, have been shown to affect immune function through changing immunoglobin or cardio-respiratory fitness levels and cell-mediated immune responses. Although calorie restriction and exercise are the most common therapies for obesity or overweight, it is unclear what kind of supplementation these people should take or how much exercise they should perform. Hence, in this study, we examined the effect of 8 weeks of high-intensity interval training (HIIT) with spirulina supplementation on the humoral immunity, cardio-respiratory fitness, and body composition of overweight and obese women. The results demonstrated that spirulina supplementation with HIIT not only decreased fat free mass but also boosted immunoglobin-A, which plays an important role in the immune system.

Abstract

Our study examined the effect of 8 weeks of high-intensity interval training (HIIT) and spirulina supplementation on the humoral immunity, cardio-respiratory fitness, and body composition of overweight and obese women. Thirty sedentary women (height: 161.7 ± 2.8 cm, body mass: 75.8 ± 8.4 kg, body mass index [BMI]: 28.8 ± 2.5 kg/m², age: 25.1 ± 6.7 years) were divided into three groups: placebo with HIIT group, spirulina group (SG), or combined group (CG). Exercise groups performed HIIT for 8 weeks, with three sessions per week and four to seven repetitions in each session of 30 s running and 30 s walking; the intensity was established at 90% of the maximum heart rate. Supplementation groups received 6 g of spirulina powder per day. Fasting blood samples were collected before and after 8 weeks to determine the concentrations of immunoglobulins (IgA and IgG). There was a significant group-by-time interaction for fat free mass (FFM; p = 0.001, f = 8.52, ηp² = 0.39) and IgA (p = 0.036, f = 3.86, ηp² = 0.22). The post hoc analysis revealed that CG reduced FFM significantly (p = 0.012, g = −0.55) after training. CG and SG showed significantly greater IgA concentrations after 8 weeks (p = 0.02, g = 0.70 and p = 0.001, g = 0.34, respectively). We conclude that spirulina supplementation with HIIT affects the body composition (lower FFM) but also boosts IgA, which plays an important role in the immune system.

Recovery of lymphocyte subpopulations is incomplete in the long-term setting in pediatric solid tumor survivors

BACKGROUND

Childhood cancer survivors (CCSs) may have comorbidities including a long-term abnormality in the immune system. Immune reconstitution in CCSs after treatment for acute leukemia has been reported previously, while analyses of immune reconstitution in CCSs with solid tumors have been limited.

METHODS

Childhood cancer survivors who received chemotherapy for solid tumors and who visited University of Tsukuba Hospital between November 2019 and March 2021 were included the study. Peripheral blood was collected for flow cytometry analysis.

RESULTS

Forty-nine samples from 35 CCSs (18 male, 17 female) were included in the study. High-dose chemotherapy and cerebral spinal irradiation were conducted in 14 CCSs (40%) and in five CCSs (14%), respectively. The median time between the completion of chemotherapy and the collection of the present samples was 15.0 months (range, 0-286 months). The total lymphocyte count, B cells, and CD8-positive T cells recovered to the normal range of controls (NR-CTLs) in 0 (0%), four (66.7%), and four (66.7%) of six samples at 0-3 months after the completion of chemotherapy, and in three (60%), four (80%), and three (60%) of five samples at 3-12 months after the completion of chemotherapy, respectively. Meanwhile, CD4-positive T cells remained lower than NR-CTLs in 0 (0%) of six samples, one (20%) of five samples, and seven (63.7%) of 11 samples at 0-3, 3-12 and 12-60 months after the completion of chemotherapy, respectively.

CONCLUSIONS

Recovery to the NR-CTLs was rapidly achieved in B cells and CD8-positive T cells, while the recovery was slower and incomplete in CD4-positive T cells. Careful observation of infection in long-term follow-up clinics is needed.

Association of dengue infection with anti-alpha-gal antibodies, IgM, IgG, IgG1, and IgG2

Dengue virus (DENV) transmitted by the Aedes mosquitoes is the etiological agent of dengue fever, one of the fastest-growing reemerging mosquito-borne diseases on the planet with a 30-fold surge in the last five decades. Interestingly, many arthropod-borne pathogens, including DENV type 2, have been reported to contain an immunogenic glycan galactose-alpha1,3-galactose (alpha-Gal or aGal). The aGal molecule is a common oligosaccharide found in many microorganisms and in most mammals, except for humans and the Old-World primates. The loss of aGal in humans is considered to be an evolutionary innovation for enabling the production of specific antibodies against aGal that could be presented on the glycan of pathogens. The objective of this study was to evaluate different anti-aGal antibodies (IgM, IgG, IgG1, and IgG2) in people exposed to DENV. We observed a significant difference in anti-aGal IgG and IgG1 levels among dengue severity classifications. Furthermore, a significant positive correlation was observed between the anti-aGal IgG and the number of days with dengue symptoms in patients. Additionally, both anti-aGal IgM and IgG levels differ between the two geographical locations of patients. While the anti-aGal IgM and IgG2 levels were not significantly different according to the dengue severity levels, age was negatively correlated with anti-aGal IgM and positively correlated with anti-aGal IgG2. Significant involvement of aGal antibodies in Dengue infection processes is suggested based on the results. Our results open the need for further studies on the exact roles and the mechanisms of the aGal antibodies in Dengue infection.

Neisseria meningitidis IgA1-specific serine protease exhibits novel cleavage activity against IgG3

Neisseria meningitidis (meningococcus) is a common bacterial colonizer of the human nasopharynx but can occasionally cause very severe systemic infections with rapid onset. Meningococci are able to degrade IgA encountered during colonization of mucosal membranes using their IgA1-specific serine protease. During systemic infection, specific IgG can induce complement-mediated lysis of the bacterium. However, meningococcal immune evasion mechanisms in thwarting IgG remain undescribed. In this study, we report for the first time that the meningococcal IgA1-specific serine protease is able to degrade IgG3 in addition to IgA. The IgG3 heavy chain is specifically cleaved in the lower hinge region thereby separating the antigen binding part from its effector binding part. Through molecular characterization, we demonstrate that meningococcal IgA1-specific serine protease of cleavage type 1 degrades both IgG3 and IgA, whereas cleavage type 2 only degrades IgA. Epidemiological analysis of 7581 clinical meningococcal isolates shows a significant higher proportion of cleavage type 1 among isolates from invasive cases compared to carrier cases, regardless of serogroup. Notably, serogroup W cc11 which is an increasing cause of invasive meningococcal disease globally harbors almost exclusively cleavage type 1 protease. Our study also shows an increasing prevalence of meningococcal isolates encoding IgA1P cleavage type 1 compared to cleavage type 2 during the observed decade (2010-2019). Altogether, our work describes a novel mechanism of IgG3 degradation by meningococci and its association to invasive meningococcal disease.

Assessing antibody decline after chemotherapy of early chronic Chagas disease patients

BACKGROUND

Chagas disease remains a significant public health problem in Latin America. There are only two chemotherapy drugs, nifurtimox and benznidazole, and both may have severe side effects. After complete chemotherapy of acute cases, seropositive diagnosis may revert to negative. However, there are no definitive parasitological or serological biomarkers of cure.

METHODS

Following a pilot study with seven Bolivian migrants to Spain, we tested 71 serum samples from chronic patients (mean age 12.6 years) inhabiting the Argentine Chaco region. Benznidazole chemotherapy (5-8 mg/kg day, twice daily for 60 days) was administered during 2011-2016. Subsequently, pre-and post-chemotherapy serum samples were analysed in pairs by IgG1 and IgG ELISA using two different antigens and Chagas Sero K-SeT rapid diagnostic tests (RDT). Molecular diagnosis by kDNA-PCR was applied to post-treatment samples.

RESULTS

Pilot data demonstrated IgG1 antibody decline in three of seven patients from Bolivia 1 year post-treatment. All Argentine patients in 2017 (averaging 5 years post-treatment), except one, were positive by conventional serology. All were kDNA-PCR-negative. Most (91.5%) pre-treatment samples were positive by the Chagas Sero K-SeT RDT, confirming the predominance of TcII/V/VI. IgG1 and IgG of Argentine patients showed significant decline in antibody titres post-chemotherapy, with either lysate (IgG, P = 0.0001, IgG1, P = 0.0001) or TcII/V/VI peptide antigen (IgG, P = 0.0001, IgG1, P = 0.0001). IgG1 decline was more discriminative than IgG. Antibody decline after treatment was also detected by the RDT. Incomplete treatment was associated with high IgG1 post-treatment titres against lysate (P = 0.013), as were IgG post-treatment titres to TcII/V/VI peptide (P = 0.0001). High pre-treatment IgG1 with lysate was associated with Qom ethnicity (P = 0.045). No associations were found between gender, age, body mass index and pre- or post-treatment antibody titres.

CONCLUSIONS

We show that following chemotherapy of early chronic Chagas disease, significant decline in IgG1 antibody suggests cure, whereas sustained or increased IgG1 is a potential indicator of treatment failure. Due to restricted sensitivity, IgG1 should not be used as a diagnostic marker but has promise, with further development, as a biomarker of cure. We show that following chemotherapy of early chronic Chagas disease, a significant decline in IgG1 antibody suggests cure, whereas sustained or increased IgG1 is a potential indicator of treatment failure. Due to restricted sensitivity, IgG1 should not be used as a diagnostic marker but has promise, with further development, as a biomarker of cure.

Neonatal Linear IgA Bullous Dermatosis Mediated by Breast Milk-Borne Maternal IgA

Importance

Neonatal linear immunoglobulin A (IgA) bullous dermatosis (LABD) is a rare disease that can be fatal when associated with respiratory failure. All previously reported cases of neonatal LABD have been in newborns with healthy asymptomatic mothers, and the pathogenic IgA was of unknown origin.

Objective

To clarify the origin of IgA associated with LABD in neonates born of healthy asymptomatic mothers.

Design, Setting, and Participants

This case study analyzed the laboratory findings of a single breast-fed newborn male with neonatal LABD admitted to the Keio University Hospital in Tokyo and his healthy asymptomatic mother. The healthy newborn developed life-threatening blisters and erosions of the skin and mucous membranes on day 4 after birth. Blood serum, skin, and maternal breast milk were examined for IgA autoantibodies.

Main Outcomes and Measures

Histopathologic and immunofluorescence analyses of specimens (serum, skin, and breast milk) from the patient and his mother.

Results

Histopathologic evaluation of the newborn's skin revealed subepidermal blisters with neutrophil infiltrates, and immunofluorescence testing showed linear IgA deposition along the basement membrane zone (BMZ), which lead to the diagnosis of neonatal LABD. Indirect immunofluorescence using normal human skin after treatment with 1-mol/L sodium chloride showed the patient to have circulating IgA binding to the dermal side of BMZ. Immunohistochemical staining proved the deposition of secretory IgA in the neonatal skin by demonstrating the presence of J chain-not been seen in other LABD cases-indicating that the autoantibodies producing the blisters were derived from the maternal breast milk. Although no circulating IgA against the skin was detected in mother's sera, the breast milk contained IgA that reacted with the dermal side of the BMZ. No new blister formation was observed after cessation of breastfeeding.

Conclusions and Relevance

The results of this case study suggest a passive transfer of pathogenic IgA to a newborn from an asymptomatic mother via breast milk. In prior reports, no serum from asymptomatic mothers of newborns with LABD had IgA autoantibodies binding to skin components; however, in this case, we found that the maternal breast milk contained IgA autoantibodies associated with neonatal LABD. In neonatal LABD, maternal breast milk should be examined for IgA autoantibodies and breast milk feeding should be discontinued as soon as neonatal LABD is suspected.

Hide and seek in a pandemic: review of SARS-CoV-2 infection and sequelae in children

New Findings

What is the topic of this review?

A description of the current literature relating to COVID‐19 infection in children and the associated inflammatory condition, paediatric multi‐inflammatory syndrome temporally associated with SARS‐CoV‐2 (PIMS‐TS).

What advances does it highlight?

Children with SARS‐CoV‐2 infection have a distinct clinical phenotype when compared to adults. This may relate to relative differences in their adaptive immunity and in the degree and distribution of expression of the SARS‐CoV‐2 receptor (angiotensin‐converting enzyme 2). There are several similarities between PIMS‐TS, Kawasaki disease shock syndrome and other known inflammatory disorders such as macrophage activation syndrome. Few data are available to date regarding vaccination responses of children against COVID‐19.

Abstract

Children infected with SARS‐CoV‐2 have a clinical phenotype that is distinct from that observed in adult cases. They can present with a range of respiratory, gastrointestinal and neurological symptoms, or with a delayed hyperinflammatory syndrome (paediatric multisystem inflammatory system temporally associated with SARS‐CoV‐2; PIMS‐TS) that frequently requires treatment in an intensive care unit. These manifestations may be related to unique expression of transmembrane receptors and immune physiology in children. The clinical features and inflammatory profile of PIMS‐TS are similar to other inflammatory disorders that occur in children such as Kawasaki disease, macrophage activation syndrome and sepsis. Given children are infected less frequently and have less severe disease due to COVID‐19 compared to adults, their physiological profile is of great interest. An understanding of the unique mechanisms of infection and disease in children could aid the identification of potential therapeutic targets. Like adults, children can have long‐term complications of SARS‐CoV‐2 infection, including neurological and cardiac morbidity. Vaccination against SARS‐CoV‐2 is not yet authorised in children aged <12 years, and hence we anticipate ongoing paediatric presentations of COVID‐19 in the coming months.

Class Switch Recombination Defects: impact on B cell maturation and antibody responses

To assess how B cell phenotype analysis correlates with antigen responses in patients with class switch recombination defects (CSRD) we quantified memory B cells by flow-cytometry and immunized CSRD patients with the neoantigen bacteriophage phiX174 (phage). CSRD patients showed uniformly absent or markedly reduced switched memory B cells (IgM^-IgD^-CD27⁺). CD40L patients had reduced CD27⁺ memory B cells (both non-switched and switched). In NEMO patients, results varied depending on the IKKγ gene variant. Three of four AID patients had normal percentages of CD27⁺ memory B cells while CD27⁺IgM^-IgD^- switched memory B cells were markedly reduced in all AID patients. Antibody response to phage was remarkably decreased with lack of memory amplification and class-switching in immunized CD40L, UNG deficient, and NEMO patients. Distinct B-cell phenotype pattern correlated with abnormal antibody responses to a T-cell dependent neoantigen, representing a powerful tool to identify CSRD patients.

Dynamics of immunoglobulin G subclasses during the first two years of life in Malawian infants born to HIV-positive mothers

Background

Maternal antibodies are key components of the protective responses of infants who are unable to produce their own IgG until 6 months of life. There is evidence that HIV-exposed uninfected children (HEU) have IgG levels abnormalities, that can be partially responsible for the higher vulnerability to infections in the first 2 years of the life of this population.

This retrospective study aimed to characterize the dynamics in plasma levels of total IgG and their isotypes during the first 2 years of life in HEU infants exclusively breastfed through 6 months of age.

Methods

Total IgG, IgG1, IgG2, IgG3 and IgG4 isotypes, and IgM and IgA plasma concentrations were determined by nephelometric methods in 30 Malawian infants born to HIV-positive women at month 1, 6 and 24 of life.

Results

At 1-month infants had a median concentration of total IgG of 8.48 g/l, (IQR 7.57–9.15), with an overrepresentation of the IgG1 isotype (89.0% of total) and low levels of IgG2 (0.52 g/l, IQR, 0.46–0.65). Total IgG and IgG1 concentrations were lower at 6 months (− 2.1 and − 1.12 g/dl, respectively) reflecting disappearance of maternal antibodies, but at 24 months their levels were higher with respect to the reported reference values for age-matched pairs. Abnormal isotype distribution was still present at 24 months with IgG2 remaining strongly underrepresented (0.87 g/l, 7.5% of total IgG).

Conclusion

HIV exposure during pregnancy and breastfeeding seems to influence the IgG maturation and isotype distribution that persist in 2-year old infants.