Helper T cell immunity in humans with inherited CD4 deficiency.

CD4+ T cells are vital for host defense and immune regulation. However, the fundamental role of CD4 itself remains enigmatic. We report seven patients aged 5-61 years from five families of four ancestries with autosomal recessive CD4 deficiency and a range of infections, including recalcitrant warts and Whipple's disease. All patients are homozygous for rare deleterious CD4 variants impacting expression of the canonical CD4 isoform. A shorter expressed isoform that interacts with LCK, but not HLA class II, is affected by only one variant. All patients lack CD4+ T cells and have increased numbers of TCRαß+CD4-CD8- T cells, which phenotypically and transcriptionally resemble conventional Th cells. Finally, patient CD4-CD8- αß T cells exhibit intact responses to HLA class II-restricted antigens and promote B cell differentiation in vitro. Thus, compensatory development of Th cells enables patients with inherited CD4 deficiency to acquire effective cellular and humoral immunity against an unexpectedly large range of pathogens. Nevertheless, CD4 is indispensable for protective immunity against at least human papillomaviruses and Trophyrema whipplei.

Combined immunodeficiency caused by pathogenic variants in the ZAP70 C-terminal SH2 domain.

Introduction: ZAP-70, a protein tyrosine kinase recruited to the T cell receptor (TCR), initiates a TCR signaling cascade upon antigen stimulation. Mutations in the ZAP70 gene cause a combined immunodeficiency characterized by low or absent CD8+ T cells and nonfunctional CD4+ T cells. Most deleterious missense ZAP70 mutations in patients are located in the kinase domain but the impact of mutations in the SH2 domains, regulating ZAP-70 recruitment to the TCR, are not well understood. Methods: Genetic analyses were performed on four patients with CD8 lymphopenia and a high resolution melting screening for ZAP70 mutations was developed. The impact of SH2 domain mutations was evaluated by biochemical and functional analyses as well as by protein modeling. Results and discussion: Genetic characterization of an infant who presented with pneumocystis pneumonia, mycobacterial infection, and an absence of CD8 T cells revealed a novel homozygous mutation in the C-terminal SH2 domain (SH2-C) of the ZAP70 gene (c.C343T, p.R170C). A distantly related second patient was found to be compound heterozygous for the R170C variant and a 13bp deletion in the ZAP70 kinase domain. While the R170C mutant was highly expressed, there was an absence of TCR-induced proliferation, associated with significantly attenuated TCR-induced ZAP-70 phosphorylation and a lack of binding of ZAP-70 to TCR-ζ. Moreover, a homozygous ZAP-70 R192W variant was identified in 2 siblings with combined immunodeficiency and CD8 lymphopenia, confirming the pathogenicity of this mutation. Structural modeling of this region revealed the critical nature of the arginines at positions 170 and 192, in concert with R190, forming a binding pocket for the phosphorylated TCR-ζ chain. Deleterious mutations in the SH2-C domain result in attenuated ZAP-70 function and clinical manifestations of immunodeficiency.

Hospital admissions for urticaria in a pediatric emergency department of a tertiary care hospital.

BACKGROUND: Urticaria is a common disorder, estimated to affect 2.1 to 6.7% of children and adolescents, and is a frequent cause of emergency department (ED) admissions. METHODS: The aim of this study was to retrospectively characterize the clinical features of children and adolescents with a diagnosis of urticaria, evaluated in a tertiary care pediatric ED between 2015 and 2019. Statistical analysis was performed using IBM SPSS Statistics®, version 27.0. RESULTS: A total of 2254 episodes of urticaria were counted with 98.1% corresponding to acute urticaria (AU). A suspected trigger factor was identified in 51.6% of the episodes, namely infections (27.8%), drugs (9.9%) and food (7.6%). From these episodes, excluding infections, only 59.2% were referred to an Allergy Consultation for further study, with only 18.8% (drug) and 28.3% (food) confirmed as the AU trigger. Of the 43 episodes of chronic urticaria (CU), 79% were referred to consultation, with 23 being diagnosed with chronic spontaneous urticaria, 8 with inducible urticaria and 3 with both entities. Older age (p < 0.001), personal history of atopy (p = 0.019) and angioedema (p = 0.003) were factors associated with CU, while the presence of other accompanying symptoms (p = 0.007) was associated with AU. Older age (OR = 1.2; p < 0.001) and the presence of angioedema (OR = 2.7; p = 0.007) were identified as independent factors for CU. CONCLUSION: The majority of episodes corresponded to AU. Infections were the main suspected trigger, followed by drugs and food, with an overall confirmation rate ranging from 18 to 30%, highlighting the importance of an allergologic follow-up evaluation.

Hospital admissions for urticaria in a pediatric emergency department of a tertiary care hospital

Background: Urticaria is a common disorder, estimated to affect 2.1 to 6.7% of children and adolescents, and is a frequent cause of emergency department (ED) admissions. Methods: The aim of this study was to retrospectively characterize the clinical features of children and adolescents with a diagnosis of urticaria, evaluated in a tertiary care pediatric ED between 2015 and 2019. Statistical analysis was performed using IBM SPSS Statistics®, version 27.0. Results: A total of 2254 episodes of urticaria were counted with 98.1% corresponding to acute urticaria (AU). A suspected trigger factor was identified in 51.6% of the episodes, namely infections (27.8%), drugs (9.9%) and food (7.6%). From these episodes, excluding infections, only 59.2% were referred to an Allergy Consultation for further study, with only 18.8% (drug) and 28.3% (food) confirmed as the AU trigger. Of the 43 episodes of chronic urticaria (CU), 79% were referred to consultation, with 23 being diagnosed with chronic spontaneous urticaria, 8 with inducible urticaria and 3 with both entities. Older age (p < 0.001), personal history of atopy (p = 0.019) and angioedema (p = 0.003) were factors associated with CU, while the presence of other accompanying symptoms (p = 0.007) was associated with AU. Older age (OR = 1.2; p < 0.001) and the presence of angioedema (OR = 2.7; p = 0.007) were identified as independent factors for CU. Conclusion: The majority of episodes corresponded to AU. Infections were the main suspected trigger, followed by drugs and food, with an overall confirmation rate ranging from 18 to 30%, highlighting the importance of an allergologic follow-up evaluation (AU)

Mastocytosis: the safety of different COVID-19 vaccines / Mastocitose: segurança de diferentes vacinas contra a COVID-19

The COVID-19 pandemic has forced the development of vaccines to fight SARS-CoV-2. After vaccination began, reports of adverse reactions, including anaphylaxis, emerged. This raised concerns about the safety of COVID-19 vaccines in patients diagnosed with mastocytosis. The authors share their experience in administering different COVID-19 vaccines to patients diagnosed with mastocytosis.

A pandemia por COVID-19 obrigou ao rápido desenvolvimento de vacinas para combate ao SARS-CoV-2. Após o início da vacinação começaram a surgir relatos de reações adversas às vacinas, incluindo reações anafiláticas, surgindo dúvidas sobre a segurança das vacinas em doentes com mastocitose. Os autores apresentam a sua experiência em relação à administração de diferentes vacinas contra a COVID-19 em doentes com diagnóstico de mastocitose.

Allergic manifestations of inborn errors of immunity and their impact on the diagnosis: A worldwide study.

Background: Allergies have long been observed in Inborn Errors of Immunity (IEI) and might even be the first presentation resulting in delayed diagnosis or misdiagnosis in some cases. However, data on the prevalence of allergic diseases among IEI patients are limited and contradictory. Objective: To provide a worldwide view of allergic diseases, across a broad spectrum of IEI, and their impact on the timely diagnosis of IEI. Methods: This is a worldwide study, conceived by the World Allergy Organization (WAO) Inborn Errors of Immunity Committee. A questionnaire was developed and pilot-tested and was sent via email to collect data from 61 immunology centers known to treat pediatric and/or adult IEI patients in 41 countries. In addition, a query was submitted to The United States Immunodeficiency Network (USIDNET) at its website. Results: Thirty centers in 23 countries caring for a total 8450 IEI patients responded. The USIDNET dataset included 2332 patients. Data from responders showed that a median (IQR) of 16.3% (10-28.8%) of patients experienced allergic diseases during the course of their IEI as follows: 3.6% (1.3-11.3%) had bronchial asthma, 3.6% (1.9-9.1%) atopic dermatitis, 3.0% (1.0-7.8%) allergic rhinitis, and 1.3% (0.5-3.3%) food allergy. As per the USIDNET data, the frequency of allergy among IEI patients was 68.8% (bronchial asthma in 46.9%). The percentage of IEI patients who presented initially with allergic disorders was 8% (5-25%) and diagnosis delay was reported in 7.5% (0.9-20.6%). Predominantly antibody deficiencies had the highest frequency of allergic disease followed by combined immunodeficiency with a frequency of 40.3% (19.2-62.5%) and 20.0% (10-32%) respectively. As per the data of centers, anaphylaxis occurred in 25/8450 patients (0.3%) whereas per USIDNET dataset, it occurred in 249/2332 (10.6%); drugs and food allergy were the main causes in both datasets. Conclusions: This multinational study brings to focus the relation between allergic diseases and IEI. Major allergies do occur in IEI patients but were less frequent than the general population. Initial presentation with allergy could adversely affect the timely diagnosis of IEI. There is a need for policies to raise awareness and educate primary care and other referring specialties on the association of allergic diseases with IEI. This study provides a network among centers for future prospective studies in the field.

Rare case of interstitial nephritis in a young adult under IgG therapy.

Immunoglobulin replacement therapy is an important therapeutic approach used in different diseases, such as immunodeficiency diseases. We report a case of a 19-year-old female patient with suspected common variable immunodeficiency who started replacement therapy with IgG. During the follow-up, she developed interstitial nephritis and the subsequent workup excluded other diseases or triggers except IgG therapy.

Allergies and COVID-19 vaccines: An ENDA/EAACI Position paper.

BACKGROUND: Anaphylaxis, which is rare, has been reported after COVID-19 vaccination, but its management is not standardized. METHOD: Members of the European Network for Drug Allergy and the European Academy of Allergy and Clinical Immunology interested in drug allergy participated in an online questionnaire on pre-vaccination screening and management of allergic reactions to COVID-19 vaccines, and literature was analysed. RESULTS: No death due to anaphylaxis to COVID-19 vaccines has been confirmed in scientific literature. Potential allergens, polyethylene glycol (PEG), polysorbate and tromethamine are excipients. The authors propose allergy evaluation of persons with the following histories: 1-anaphylaxis to injectable drug or vaccine containing PEG or derivatives; 2-anaphylaxis to oral/topical PEG containing products; 3-recurrent anaphylaxis of unknown cause; 4-suspected or confirmed allergy to any mRNA vaccine; and 5-confirmed allergy to PEG or derivatives. We recommend a prick-to-prick skin test with the left-over solution in the suspected vaccine vial to avoid waste. Prick test panel should include PEG 4000 or 3500, PEG 2000 and polysorbate 80. The value of in vitro test is arguable. CONCLUSIONS: These recommendations will lead to a better knowledge of the management and mechanisms involved in anaphylaxis to COVID-19 vaccines and enable more people with history of allergy to be vaccinated.

Hypersensitivity Reactions to Vaccines: Current Evidence and Standards for SARS-CoV-2 Vaccines.

The first reports of hypersensitivity reactions following the rollout of COVID-19 vaccination programs have raised public concern. Given the recent availability and novel mechanisms of COVID-19 vaccines, there is limited data on possible hypersensitivity reactions. Although it seems rare, the incidence of anaphylaxis for approved COVID-19 vaccines has been suggested as being higher when compared to previous vaccines. Adequate risk assessment, recognition, classification, and management of hypersensitivity reactions is crucial to ensure safe immunization and avoid misinformation and vaccine hesitancy. In this review, we present an overview of the types of hypersensitivity reactions that can potentially occur due to vaccination and the possible allergenic components of COVID-19 vaccines, as well as a suggestion for causality and risk assessment for the BNT162b2, mRNA-1273 and AZD1222 vaccines.

Após o início dos programas de vacinação contra a COVID-19, os primeiros relatos de reações de hipersensibilidade suscitaram alguma preocupação. Dada a recente disponibilidade e os novos mecanismos das vacinas contra a COVID-19, existem poucos dados relativos a possíveis reações de hipersensibilidade. A incidência de anafilaxia às vacinas COVID-19 parece ser mais elevada comparativamente a vacinas anteriores, embora seja igualmente rara. Uma avaliação adequada dos riscos, reconhecimento, classificação e correta abordagem das reações de hipersensibilidade é crucial para garantir uma imunização segura e evitar desinformação e hesitação na vacinação. Nesta revisão, apresentamos uma visão geral das potenciais reações de hipersensibilidade que podem ocorrer após a vacinação com as vacinas BNT162b2, mRNA-1273 e AZD1222, os seus possíveis constituintes alergénicos, bem como uma sugestão de avaliação do risco em doentes alérgicos e causalidade.

Anaphylaxis in children and adolescents: The Portuguese Anaphylaxis Registry.

BACKGROUND: Anaphylaxis is increasing at pediatric age; however, its characterization is hampered by underdiagnosis and underreporting. The aim of this study was to identify the causes of anaphylaxis in children and adolescents in Portugal, thus contributing to a better knowledge of its etiology, clinical manifestations, and management. METHODS: During a 10-year period, a nationwide notification system for anaphylaxis was implemented, with voluntary reporting by allergists. Data on 533 patients under 18 years of age with anaphylaxis were included. RESULTS: Mean age was 8.5 ± 4.9 years, 61% were male; 45% had asthma. Mean age at the first anaphylaxis episode was 5.3 ± 4.7 years (ranging from 1 month to 17 years of age), 63% at pre-school age. Most reactions occurred at home (57%). Food-induced anaphylaxis was the leading cause (77%). The main culprit foods were cow's milk (32%), tree nuts (16%), shellfish (13%), egg (12%), fresh fruits (11%), fish (8%), and peanut (8%). Other causes included drugs (11%), insect sting (5%), cold-induced anaphylaxis (4%), exercise-induced anaphylaxis (2%), latex (1%), and idiopathic anaphylaxis (1%). Most patients (83%) were admitted to the emergency department; only 46% received adrenaline treatment. Recurrence of anaphylaxis occurred in 41% of the patients (3 or more episodes in 21%). An adrenaline autoinjector was used in 9% of the patients. CONCLUSIONS: In the Portuguese pediatric population, food is the leading cause of anaphylaxis. Undertreatment with adrenaline and high recurrence of anaphylaxis highlight the need to improve both the diagnosis and the therapeutic management of this life-threatening entity.

The Dysfunctional Immune System in Common Variable Immunodeficiency Increases the Susceptibility to Gastric Cancer.

Gastric carcinoma (GC) represents the most common cause of death in patients with common variable immunodeficiency (CVID). However, a limited number of cases have been characterised so far. In this study, we analysed the clinical features, bacterial/viral infections, detailed morphology and immune microenvironment of nine CVID patients with GC. The study of the immune microenvironment included automated digital counts of CD20+, CD4+, CD8+, FOXP3+, GATA3+ and CD138+ immune cells, as well as the evaluation of PD-L1 expression. Twenty-one GCs from non-CVID patients were used as a control group. GC in CVID patients was diagnosed mostly at early-stage (n = 6/9; 66.7%) and at younger age (median-age: 43y), when compared to non-CVID patients (p < 0.001). GC pathogenesis was closely related to Helicobacter pylori infection (n = 8/9; 88.9%), but not to Epstein-Barr virus (0.0%) or cytomegalovirus infection (0.0%). Non-neoplastic mucosa (non-NM) in CVID-patients displayed prominent lymphocytic gastritis (100%) and a dysfunctional immune microenvironment, characterised by higher rates of CD4+/CD8+/Foxp3+/GATA3+/PD-L1+ immune cells and the expected paucity of CD20+ B-lymphocytes and CD138+ plasma cells, when compared to non-CVID patients (p < 0.05). Changes in the immune microenvironment between non-NM and GC were not equivalent in CVID and non-CVID patients, reflecting the relevance of immune dysfunction for gastric carcinogenesis and GC progression in the CVID population.

A new terminal nonsense mutation of the cathepsin C gene in a patient with atypical Papillon-Lefèvre syndrome

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Complete Multilineage CD4 Expression Defect Associated With Warts Due to an Inherited Homozygous CD4 Gene Mutation.

Idiopathic T-CD4 lymphocytopenia (ICL) is a rare and heterogeneous syndrome characterized by opportunistic infections due to reduced CD4 T-lymphocytes (<300 cells/µl or <20% T-cells) in the absence of HIV infection and other primary causes of lymphopenia. Molecular testing of ICL has revealed defects in genes not specific to CD4 T-cells, with pleiotropic effects on other cell types. Here we report for the first time an absolute CD4 lymphocytopenia (<0.01 CD4+ T-cells/µl) due to an autosomal recessive CD4 gene mutation that completely abrogates CD4 protein expression on the surface membrane of T-cells, monocytes, and dendritic cells. A 45-year-old female born to consanguineous parents consulted because of exuberant, relapsing, and treatment-refractory warts on her hands and feet since the age of 10 years, in the absence of other recurrent infections or symptoms. Serological studies were negative for severe infections, including HIV 1/2, HTLV-1, and syphilis, but positive for CMV and EBV. Blood analysis showed the absence of CD4+ T-cells (<0.01%) with repeatedly increased counts of B-cells, naïve CD8+ T-lymphocytes, and particularly, CD4/CD8 double-negative (DN) TCRαß+ TCRγδ- T-cells (30% of T-cells; 400 cells/µl). Flow cytometric staining of CD4 using monoclonal antibodies directed against five different epitopes, located in two different domains of the protein, confirmed no cell surface membrane or intracytoplasmic expression of CD4 on T-cells, monocytes, and dendritic cells but normal soluble CD4 plasma levels. DN T-cells showed a phenotypic and functional profile similar to normal CD4+ T-cells as regards expression of maturation markers, T-helper and T-regulatory chemokine receptors, TCRvß repertoire, and in vitro cytokine production against polyclonal and antigen-specific stimuli. Sequencing of the CD4 gene revealed a homozygous (splicing) mutation affecting the last bp on intron 7-8, leading to deletion of the juxtamembrane and intracellular domains of the protein and complete abrogation of CD4 expression on the cell membrane. These findings support previous studies in CD4 KO mice suggesting that surrogate DN helper and regulatory T-cells capable of supporting antigen-specific immune responses are produced in the absence of CD4 signaling and point out the need for better understanding the role of CD4 on thymic selection and the immune response.

The Portuguese Severe Asthma Registry: Development, Features, and Data Sharing Policies.

The Portuguese Severe Asthma Registry (Registo de Asma Grave Portugal, RAG) was developed by an open collaborative network of asthma specialists. RAG collects data from adults and pediatric severe asthma patients that despite treatment optimization and adequate management of comorbidities require step 4/5 treatment according to GINA recommendations. In this paper, we describe the development and implementation of RAG, its features, and data sharing policies. The contents and structure of RAG were defined in a multistep consensus process. A pilot version was pretested and iteratively improved. The selection of data elements for RAG considered other severe asthma registries, aiming at characterizing the patient's clinical status whilst avoiding overloading the standard workflow of the clinical appointment. Features of RAG include automatic assessment of eligibility, easy data input, and exportable data in natural language that can be pasted directly in patients' electronic health record and security features to enable data sharing (among researchers and with other international databases) without compromising patients' confidentiality. RAG is a national web-based disease registry of severe asthma patients, available at asmagrave.pt. It allows prospective clinical data collection, promotes standardized care and collaborative clinical research, and may contribute to inform evidence-based healthcare policies for severe asthma.

Gluten-free diet: a possible treatment for chronic diarrhoea in common variable immunodeficiency.

Gastrointestinal disorders are frequent in common variable immunodeficiency (CVID). Clinical symptoms and histological alterations in CIVD can resemble celiac disease. Usually, patients with chronic diarrhoea associated with CVID do not improve with a gluten-free diet. The authors present a case of a male patient who was diagnosed with CVID at age 33 and had chronic diarrhoea which resolved after initiating a gluten-free diet. Clinical relapse occurred after gluten reintroduction. The main objective of this case report is to alert clinicians to implement a gluten-free diet in patients with CVID with chronic diarrhoea.

Inborn Errors of RNA Lariat Metabolism in Humans with Brainstem Viral Infection.

Viruses that are typically benign sometimes invade the brainstem in otherwise healthy children. We report bi-allelic DBR1 mutations in unrelated patients from different ethnicities, each of whom had brainstem infection due to herpes simplex virus 1 (HSV1), influenza virus, or norovirus. DBR1 encodes the only known RNA lariat debranching enzyme. We show that DBR1 expression is ubiquitous, but strongest in the spinal cord and brainstem. We also show that all DBR1 mutant alleles are severely hypomorphic, in terms of expression and function. The fibroblasts of DBR1-mutated patients contain higher RNA lariat levels than control cells, this difference becoming even more marked during HSV1 infection. Finally, we show that the patients' fibroblasts are highly susceptible to HSV1. RNA lariat accumulation and viral susceptibility are rescued by wild-type DBR1. Autosomal recessive, partial DBR1 deficiency underlies viral infection of the brainstem in humans through the disruption of tissue-specific and cell-intrinsic immunity to viruses.

Hypersensitivity Reactions to Nonsteroidal Anti-Inflammatory Drugs among Adults: Clinical Features and Risk Factors for Diagnosis Confirmation.

BACKGROUND: Nonsteroidal anti-inflammatory drugs (NSAIDS) are among the most common causes of drug hypersensitivity (HS) reactions. The diagnosis is based on a careful clinical history, and provocation tests are considered the gold standard for diagnosis. Skin tests have some value to study reactions to pyrazolones. Laboratory investigations are mostly used for research purposes. Different phenotypes have been described. OBJECTIVE AND METHODS: Our aim was to describe the most common clinical manifestations of NSAID HS in a large population of adult patients, the drugs involved, the association with previously described risk factors, and the outcome of diagnostic procedures. The classification of reactions proposed by the European Academy of Allergy and Clinical Immunology (EAACI) Drug Allergy Interest Group was adopted. RESULTS: Acetylsalicylic acid was the drug most often involved in reactions (34%), isolated cutaneous symptoms were the most reported (60%), and immediate reactions (58%) were the most common. There was an overall female predominance (64%) and 35% of the patients were atopic. HS to NSAIDs was confirmed in 21% of the patients. The most common phenotypes encountered among HS patients were NSAID-induced urticaria/angioedema and single-NSAID-induced urticaria/angioedema or anaphylaxis. Logistic regression analysis showed that gender and atopy were not significant risk factors for HS confirmation, but diagnosis depended on the number of previous reactions, the type of reaction, and the time interval between drug intake and reaction. CONCLUSION: Only 21% of suspected HS reactions were confirmed after diagnostic workup. Patients describing >1 previous reaction and suffering immediate reactions had a higher probability of a positive investigation.