The Very Low IgE Producer: Allergology, Genetics, Immunodeficiencies, and Oncology

Total IgE levels are associated with mortality risk partially mediated by vitamin status: A nationally representative population-based study

BACKGROUND AND AIMS

Elevated total IgE levels are traditionally associated with allergic conditions; however, their potential role as biomarker for mortality risk beyond allergic diseases has not been extensively explored. Recent studies have suggested that IgE is associated with cardiovascular (CV) disease. We aimed to investigate the association between total IgE levels and the risk of all-cause and cause-specific mortality, as well as to explore the potential mediating role of vitamin status in these associations.

METHODS AND RESULTS

The association between IgE and mortality risk was examined in the National Health and Examination Survey 2005-2006. Weighted multivariable Cox proportional hazards model was employed. We further performed restricted cubic spline analysis to assess dose-response relationships and conducted mediation analysis to explore the influence of vitamins on IgE-related mortality risk. Individuals in the highest total IgE quantile (>107.0 kU/L) exhibited a 32 % increased risk of all-cause mortality (95 % CI: 1.07-1.64) and a 98 % elevated risk of CV mortality (95 % CI: 1.28-3.07) compared to the lowest quantile (<14.5 kU/L). Heterogeneity exists in the dose-response relationship and threshold effects among individuals with and without allergic diseases. Vitamin deficiency is associated with elevated total IgE levels, and vitamins mediated the relationship of the IgE-related all-cause mortality with the proportion of mediation ranging from 4.68 to 12.71 %.

CONCLUSIONS

Our findings introduce a novel dimension to the understanding of IgE as a biomarker for mortality beyond its traditional role in allergic diseases, challenging the current paradigm that elevated IgE levels without overt allergic symptoms are benign.

Molecular allergy diagnosis enabling personalized medicine

Allergic patients are characterized by complex and patient-specific IgE sensitization profiles to various allergens, which are accompanied by different phenotypes of allergic disease. Molecular allergy diagnosis establishes the patient's IgE reactivity profile at a molecular allergen level and has moved allergology into the era of precision medicine. Molecular allergology started in the late 1980s with the isolation of the first allergen-encoding DNA sequences. Already in 2002, the first allergen microarrays were developed for the assessment of complex IgE sensitization patterns. Recombinant allergens are used for a precise definition of personal IgE reactivity profiles, identification of genuine IgE sensitization to allergen sources for refined prescription of allergen-specific immunotherapy and allergen avoidance diagnosis of co- versus cross-sensitization, epidemiologic studies, and prediction of symptoms, phenotypes, and development of allergic disease. For example, molecular IgE sensitization patterns associated with more severe respiratory allergies, severe food allergy, and allergy to honeybee or vespids are already established. The implementation of molecular allergy diagnosis into daily clinical practice requires continuous medical education and training doctors in molecular allergy diagnosis, and may be facilitated by clinical decision support systems such as diagnostic algorithms that may take advantage of artificial intelligence.

The use and implementation of omalizumab as food allergy treatment: Consensus-based guidance and Work Group Report of the Adverse Reactions to Foods Committee of the American Academy of Allergy, Asthma & Immunology

Omalizumab was recently approved by the US Food and Drug Administration for treatment of any single food allergy or multiple food allergies in children aged 1 year and older and adults. There is currently no formal guidance regarding recommended best practices for omalizumab use in food allergy, including patient selection, anticipated goals and outcomes of therapy, procedure for monitoring patients who elect to start omalizumab therapy, and ways in which omalizumab can be incorporated into the landscape of food allergy management and daily clinical practice. This work group report was developed by the food allergy therapies subcommittee of the Adverse Reactions to Foods Committee within the American Academy of Allergy, Asthma & Immunology. Consensus, evidence-based guidance regarding experts' recommendations for using omalizumab to treat children and adults with food allergy was developed by using modified Delphi methodology. In iterative fashion, a total of 8 statements regarding how to use omalizumab to treat patients with food allergy were developed by 16 clinical experts. This guidance provides the clinician with a suggested approach to patient selection, initiation of therapy, monitoring of efficacy, and long-term follow-up care. The role of preference-sensitive care is emphasized, with most statements offering care recommendations relevant to the culture and values of a particular practice setting.

Characteristics of patients with low serum IgE levels and selective IgE deficiency: Data from an immunodeficiency referral center

Low immunoglobulin E (IgE) levels are defined as values below 2.5 IU/mL. Selective IgE deficiency (sIgED) refers to reduced serum IgE levels in patients with normal IgA/G/M levels. We evaluated 677 patients with low IgE levels. Recurrent infections (78.8 %), a history of allergy (27.3 %), and autoimmune/inflammatory diseases (18.3 %) are common. The primary immunodeficiency disease (PID) (n = 483, 71.3 %) diagnoses include 313 (46.2 %) patients with antibody deficiency and 119 (17.6 %) with combined immunodeficiency. Genetic pathogenic variants were present in 154 out of 207 PID patients. Within sIgED group, 23 (19.8 %) had primary immunodeficiencies. We observed a high prevalence of autoimmune/inflammatory diseases, allergies, malignancies, and PID among patients with low IgE levels. Therefore, clinicians should be vigilant when evaluating patients with low IgE levels, as this finding may indicate an underlying systemic disease or PID.

Various clinical manifestations of 223 patients with IgE deficiency in a tertiary hospital in China: A cross-sectional study

High Immunoglobulin E(IgE) levels associated with hypersensitivity or parasitic infection were well established, but the clinical significance of ultra-low IgE was largely unknown. Previous studies indicated these patients have an elevated risk of cancer, but large-scale epidemiological studies on the prevalence and clinical manifestations of these ultra-low IgE patients are still lacking. A total of 62,997 patients who were admitted to the First Affiliated Hospital of Wenzhou Medical University and had IgE level tests from January 2010 to March 2020 were included. Patients with serum IgE levels < 2 IU/mL were defined to have ultra-low IgE. And the clinical characteristics of these patients were retrospectively analyzed based on electronic medical record system and follow-up. A total of 223 patients (223/62,997, 0.35%) had ultra-low IgE were documented in 62,997 patients who had IgE tests. Among the clinical manifestations of these 223 ultra-low IgE patients, infection ranked first (125/223, 56.05%), following allergic diseases (51/223, 22.87%), hematological disorders (37/223, 16.59%), tumor (27/223, 12.11%) and autoimmune diseases (23/223, 10.31%). To the best of our knowledge, we first reported that the prevalence and clinical characteristics of 223 ultra-low IgE patients in China. The most common comorbidities were infection, allergic diseases, hematological disorders, tumor and autoimmune diseases.

A practical guide for implementing omalizumab therapy for food allergy

The recent approval of omalizumab for the treatment of IgE-mediated food allergy is an important step forward for the millions of food allergy patients in the United States. Through the depletion of circulating IgE and the subsequent reduction of FcεR1 on key effector cells, patients increase their tolerance to food allergens. However, omalizumab does not permit patients to eat foods that they are allergic to with impunity. Rather, it protects them from most accidental exposures. In addition, omalizumab does not cure food allergy and has not demonstrated true immunomodulation. Thus, omalizumab might be a lifelong therapy for some patients. Furthermore, there are many important questions and issues surrounding the appropriate administration of omalizumab to treat food allergy, which we discuss. Managing treatment of patients with disease that falls outside the dosing range, assessing treatment response or nonresponse, addressing its appropriateness for patients older than 55, and determining whether immunotherapy plus omalizumab provides any advantage over omalizumab alone all need to be examined. Identifying appropriate patients for this therapy is critical given the cost of biologics. Indeed, not all food allergy patients are good candidates for this therapy. Also, when and how to stop omalizumab therapy in patients who may have outgrown their food allergy needs to be elucidated. Thus, although this therapy provides a good option for patients with food allergies, much information is needed to determine how best to use this therapy. Despite many unanswered questions and issues, we provide clinicians with some practical guidance on implementing this therapy in their patients.

Editorial to the Special Issue "Clinical Immunology in Italy, with Special Emphasis to Primary and Acquired Immunodeficiencies: A Commemorative Issue in Honor of Prof. Fernando Aiuti"

Fernando Aiuti (Figure 1), born in Urbino on 8 June 1935, suddenly died on 9 January 2019, leaving a great void not only among his family members and those who knew him and appreciated his great humanity and acute intelligence, but in the entire immunological scientific community [...].

Elevated IgE Levels-An Allergy or an Underlying Inborn Error of Immunity in Children with Recurrent Infections?

Elevated immunoglobulin E (IgE) is a hallmark of allergic diseases. However, high IgE levels also occur in a number of other infectious and noninfectious diseases. In most cases, elevated IgE levels indicate allergy, eczema, or chronic skin infection. Very high IgE levels are not uncommon in patients with active eczema but more often indicate monogenic atopic disorder or inborn errors of immunity with an atopic phenotype. We conducted a retrospective study of 385 children with suspected immune deficiency referred to the clinic over a 9-year period. Measurement of IgE, IgG, IgA, IgM, and IgG subclasses in blood samples revealed that nearly one-third of the patients had elevated serum IgE levels. Most of the cases with elevated IgE were children with underlying atopy-mainly atopic dermatitis and, to a lesser extent, bronchial asthma-whereas 40.12% (37 children) had no atopy at all. In the most severe cases (with extremely elevated IgE or severe dermatitis), we confirmed genetic mutations for underlying immunodeficiency. Our results indicate that allergic phenotype should not be underestimated and that children with more severe allergic disease should be evaluated for an underlying inborn error of immunity. If inborn error of immunity (IEI) is suspected, a comprehensive immunologic evaluation is required. Genetic testing helps identify the specific genetic abnormality, which provides important insight into the immunopathogenesis of the disease and accurate determination of optimal therapy.

A Food Matrix Triggers a Similar Allergic Immune Response in BALB/c Mice Sensitized with Native, Denatured, and Digested Ovalbumin

The search for an animal model to evaluate the allergenic potential of processed food products is still ongoing. Both the sensitization to ovalbumin (OVA) in different structural states and the allergic response triggered after intragastric or food challenges were assessed. BALB/c mice were sensitized intraperitoneally to OVA (50 µg) in different structural states (native OVA, N-OVA; denatured OVA, D-OVA; formaldehyde- and lysine-treated OVA, FK-OVA; denatured OVA-FK, OVA-DFK; peptides from pepsin digestion, Pep-OVA). Anti-OVA-specific IgE responses were evaluated using ELISA. Anaphylactic signs and mMCP-1 serum levels were evaluated after intragastric (2.0 mg/OVA) and food (0.41 mg/OVA) challenges. IgE reactivities to N-OVA and D-OVA were similar among groups (p > 0.05). After the challenges, all OVA-sensitized mice developed mild to severe anaphylactic signs (p < 0.05 vs. control). Mice sensitized to N-OVA and D-OVA had the highest mMCP-1 serum levels after challenges (p < 0.05 vs. control). Allergic responses were similar despite the different OVA doses used for the challenges. The N-OVA-sensitized murine model of egg allergy proposed in the present study holds the potential for evaluating the impact of food matrix composition and processing on the threshold of egg-allergic responses.