Tryptase levels in children presenting with anaphylaxis: Temporal trends and associated factors

Protective role of protease-activated receptor-2 in anaphylaxis model mice

Anaphylaxis is a severe life-threatening hypersensitivity reaction induced by mast cell degranulation. Among the various mediators of mast cells, little is known about the role of tryptase. Therefore, we aimed to elucidate the role of protease-activating receptor-2 (PAR-2), a receptor activated by tryptase, in murine anaphylactic models using PAR-2-deficient mice and newly generated tryptase-deficient mice. Anaphylaxis was induced by IgE-dependent and IgE-independent mast cell degranulation in mice. PAR-2 deficiency exacerbated the decrease in body temperature and hypotension during anaphylaxis; however, the number of skin mast cells, degree of mast cell degranulation, and systemic and local vascular hyperpermeability were comparable in PAR-2 knockout and wild-type mice. Nitric oxide, which is produced by endothelial nitric oxide synthase (eNOS), is an indispensable vasodilator in anaphylaxis. In the lungs of anaphylactic mice, PAR-2 deficiency promoted eNOS expression and phosphorylation, suggesting a protective effect of PAR-2 against anaphylaxis by downregulating eNOS activation and expression. Based on the hypothesis that the ligand for PAR-2 in anaphylaxis is mast cell tryptase, tryptase-deficient mice were generated using CRISPR-Cas9. In wild-type mice, the PAR-2 antagonist exacerbated the body temperature drop due to anaphylaxis; however, the effect of the PAR-2 antagonist was abolished in tryptase-deficient mice. These results suggest that tryptase is a possible ligand of PAR-2 in anaphylaxis and that the tryptase/PAR-2 pathway attenuates the anaphylactic response in mice.

Reversible Elevation of Tryptase Over the Individual's Baseline: Why is It the Best Biomarker for Severe Systemic Mast Cell Activation and MCAS?

PURPOSE OF REVIEW

Mast cell (MC) activation syndromes (MCAS) are conditions defined by recurrent episodes of severe systemic anaphylaxis or similar systemic events triggered by MC-derived mediators that can be measured in biological fluids. Since some symptoms of MC activation may occur due to other, non-MC etiologies and lead to confusion over diagnosis, it is of crucial importance to document the involvement of MC and their products in the patients´ symptomatology.

RECENT FINDINGS

The most specific and generally accepted marker of severe systemic MC activation is an event-related, transient increase in the serum tryptase level over the individual baseline of the affected individual. However, baseline concentrations of serum tryptase vary among donors, depending on the genetic background, age, kidney function, and underlying disease. As a result, it is of critical importance to provide a flexible equation that defines the diagnostic increase in tryptase qualifying as MCAS criterion in all patients, all situations, and all ranges of baseline serum tryptase. In 2012, the consensus group proposed the 120% + 2 ng/ml formula, which covers the great majority of groups, including cases with low, normal, or elevated basal serum tryptase level. This formula has been validated in subsequent studies and has proven to be a robust and consistent diagnostic criterion of MCAS. The present article is discussing the impact of this formula and possible limitations as well as alternative markers and mediators that may be indicative of MCAS.

Anaphylaxis: A 2023 practice parameter update

This practice parameter update focuses on 7 areas in which there are new evidence and new recommendations. Diagnostic criteria for anaphylaxis have been revised, and patterns of anaphylaxis are defined. Measurement of serum tryptase is important for diagnosis of anaphylaxis and to identify underlying mast cell disorders. In infants and toddlers, age-specific symptoms may differ from older children and adults, patient age is not correlated with reaction severity, and anaphylaxis is unlikely to be the initial reaction to an allergen on first exposure. Different community settings for anaphylaxis require specific measures for prevention and treatment of anaphylaxis. Optimal prescribing and use of epinephrine autoinjector devices require specific counseling and training of patients and caregivers, including when and how to administer the epinephrine autoinjector and whether and when to call 911. If epinephrine is used promptly, immediate activation of emergency medical services may not be required if the patient experiences a prompt, complete, and durable response. For most medical indications, the risk of stopping or changing beta-blocker or angiotensin-converting enzyme inhibitor medication may exceed the risk of more severe anaphylaxis if the medication is continued, especially in patients with insect sting anaphylaxis. Evaluation for mastocytosis, including a bone marrow biopsy, should be considered for adult patients with severe insect sting anaphylaxis or recurrent idiopathic anaphylaxis. After perioperative anaphylaxis, repeat anesthesia may proceed in the context of shared decision-making and based on the history and results of diagnostic evaluation with skin tests or in vitro tests when available, and supervised challenge when necessary.

CD4+CD25+CD127loFOXP3+ cell in food allergy: Does it predict anaphylaxis?

BACKGROUND

Food allergy (FA), hence the incidence of food anaphylaxis, is a public health problem that has increased in recent years. There are still no biomarkers for patients with FA to predict severe allergic reactions such as anaphylaxis.

OBJECTIVE

There is limited information on whether regulatory T (Treg) cell levels are a biomarker that predicts clinical severity in cases presenting with FA, and which patients are at a greater risk for anaphylaxis.

METHODS

A total of 70 children were included in the study: 25 who had IgE-mediated cow's milk protein allergy (CMPA) and presented with non-anaphylactic symptoms (FA/A-), 16 who had IgE-mediated CMPA and presented with anaphylaxis (FA/A+) (a total of 41 FA cases), and a control group consisting of 29 children without FA. The study was conducted by performing CD4+CD25+CD127^loFOXP3+ cell flow cytometric analysis during resting at least 2 weeks after the elimination diet to FA subjects.

RESULTS

When the FA group was compared with healthy control subjects, CD4+CD25+CD127_loFOXP3+ cell rates were found to be significantly lower in the FA group (p < 0.001). When the FA/A- and FA/A+ groups and the control group were compared in terms of CD4+CD25+CD127^loFOXP3+ cell ratios, they were significantly lower in the FA/A- and FA/A+ groups compared to the control group (p < 0.001).

CONCLUSIONS

Although there was no significant difference between the FA/A+ group and the FA/A- group in terms of CD4+CD25+CD127^loFOXP3+ cells, our study is important, as it is the first pediatric study we know to investigate whether CD4+CD25+CD127^loFOXP3+ cells in FA predict anaphylaxis.

Risk factors for severe reactions in food allergy: Rapid evidence review with meta-analysis

This rapid review summarizes the most up to date evidence about the risk factors for severe food-induced allergic reactions. We searched three bibliographic databases for studies published between January 2010 and August 2021. We included 88 studies and synthesized the evidence narratively, undertaking meta-analysis where appropriate. Significant uncertainties remain with respect to the prediction of severe reactions, both anaphylaxis and/or severe anaphylaxis refractory to treatment. Prior anaphylaxis, an asthma diagnosis, IgE sensitization or basophil activation tests are not good predictors. Some molecular allergology markers may be helpful. Hospital presentations for anaphylaxis are highest in young children, yet this age group appears at lower risk of severe outcomes. Risk of severe outcomes is greatest in adolescence and young adulthood, but the contribution of risk taking behaviour in contributing to severe outcomes is unclear. Evidence for an impact of cofactors on severity is lacking, although food-dependent exercise-induced anaphylaxis may be an exception. Some medications such as beta-blockers or ACE inhibitors may increase severity, but appear less important than age as a factor in life-threatening reactions. The relationship between dose of exposure and severity is unclear. Delays in symptom recognition and anaphylaxis treatment have been associated with more severe outcomes. An absence of prior anaphylaxis does not exclude its future risk.

Clinical utility of serum tryptase levels in pediatric anaphylaxis

Introduction: This study aimed to evaluate the preliminary diagnosis, demographic characteristics, and outcomes of patients whose serum total tryptase levels were measured while in a tertiary pediatric hospital and to ascertain the role of serum tryptase levels in the etiology, diagnosis, severity, and course of systemic anaphylaxis. Methods: Patients ages between 1 month and 17 years who were followed up in the pediatric emergency department or as inpatients and with a diagnosis of immediate-type reactions between September 1, 2019, and August 31, 2021, were included in the study. Patient data were obtained retrospectively by examination of medical records and patient observation forms. Results: It was determined that serum tryptase levels were measured in a total of 310 patients during the study period. One hundred and fifty-five patients who met the defined diagnostic criteria were named as the anaphylaxis group and their data were detailed. The serum tryptase elevation was detected in 15.5% of the patients among the samples that met the anaphylaxis diagnostic criteria. No relationship was found between the serum total tryptase levels, the triggering factor, and the severity of anaphylaxis. Discussion: Anaphylaxis is a complex syndrome that involves different phenotypes that develop with various triggers in which different immunologic pathways, cell types, and mediators play a role. Serial measurements, including the basal value measured at least 24 hours after the symptoms disappear, are useful to confirm the diagnosis and guide the diagnostic tests during the follow-up, especially allergy evaluation.

Incorporating Tryptase Genotyping Into the Workup and Diagnosis of Mast Cell Diseases and Reactions

The measurement of mast cell tryptase levels in serum has found utility in the diagnosis and management of both clonal mast cell disorders and severe mast cell-dependent systemic reactions in the form of anaphylaxis. A more recent discovery is that a majority of individuals with elevated basal serum tryptase levels have increased germline TPSAB1 gene copy number encoding α-tryptase. This genetic trait is referred to as hereditary α-tryptasemia (HαT) and affects nearly 6% of the general population. In clinical practice, the presence or absence of HαT should thus now be determined when defining what constitutes an abnormal serum tryptase level in the diagnosis of mastocytosis. Further, as rises in serum tryptase levels are used to support the diagnosis of systemic anaphylaxis, variability in baseline serum tryptase levels should be factored into how significant a rise in serum tryptase is required to confirm the diagnosis of a systemic allergic reaction. In practicality, this dictates that symptomatic individuals undergoing evaluation for a mast cell-associated disorder or reaction with a baseline serum tryptase level exceeding 6.5 ng/mL should be considered for tryptase genotyping in order to screen for HαT. This review provides detailed information on how to use the results of such testing in the diagnosis and management of both mastocytosis and anaphylaxis.

Economic burden of food allergy in Canada: Estimating costs and identifying determinants

BACKGROUND

Limited data exist on the economic burden of food allergy (FA).

OBJECTIVE

To assess FA-related direct (healthcare and out-of-pocket) and indirect (lost productivity) costs and their determinants in Canadian children and adults self-reporting FA.

METHODS

FA-individuals self-reporting a convincing history or physician diagnosis were recruited through FA registries, an anaphylaxis registry, and advocacy associations, and electronically surveyed regarding FA-related healthcare use, out-of-pocket expenditures, and time lost from paid and unpaid labor. Direct and indirect costs (2020 Canadian dollars [CAD]) were stratified on severe reaction vs mild, moderate or no reaction, and children vs adults; multivariate regressions assessed the association between costs and sociodemographic and disease characteristics.

RESULTS

Between May 2018 and July 2019, 2692 eligible individuals responded (2189 convincing history and 503 physician diagnosis only); 1020 experienced a severe reaction; 1752 were children. Per FA-individual, annual healthcare, out-of-pocket, and indirect costs were $1267, $2136, and $7950. Those with a severe reaction had higher healthcare and out-of-pocket costs than those with mild, moderate or no reaction. FA-children vs FA-adults had higher healthcare and out-of-pocket costs, and lower indirect costs. Multivariate results showed that lower age, a severe reaction ever, multiple FAs, and fair or poor general health were associated with higher healthcare and out-of-pocket costs. Higher age, lower household education and income, and fair or poor general health were associated with higher indirect costs.

CONCLUSION

The economic burden of FA in Canada is substantial, particularly for those with a severe reaction ever, multiple FAs, and fair or poor general health. It is crucial that those most adversely affected are allocated appropriate resources to support disease management.

Management of Anaphylaxis in Infants and Toddlers

Anaphylaxis is a systemic allergic reaction that can be caused by food, drugs, insect bites, or unknown triggers in infants and toddlers. Anaphylaxis rates are increasing. Infants and toddlers may have increased exposure to known and unknown allergens, decreased ability to describe their symptoms, and an expanded differential diagnosis for consideration on presentation. The most common symptoms in these age groups are cutaneous and gastrointestinal. Age-specific language may be helpful for caregivers to identify and describe the symptoms of anaphylaxis in infants and toddlers. Long-term management of anaphylaxis includes allergy evaluation to guide avoidance and assess prognosis and education on allergic reaction management; this incorporates the prescription of epinephrine autoinjector and provision of an allergy emergency plan.

Idiopathic anaphylaxis: Diagnosis and management

Introduction: Idiopathic anaphylaxis (IA) is a diagnosis of exclusion and is based on the inability to identify a causal relationship between a trigger and an anaphylactic event, despite a detailed patient history and careful diagnostic assessment. The prevalence of IA among the subset of people who experienced anaphylaxis is challenging to estimate and varies widely, from 10 to 60%; most commonly noted is ∼20% in the adult anaphylactic population. Comorbid atopic conditions, such as food allergy, allergic rhinitis, and asthma, are present in up to 48% of patients with IA. Improved diagnostic technologies and an increased understanding of conditions that manifest with symptoms associated with anaphylaxis have improved the ability to determine a more accurate diagnosis for patients who may have been initially diagnosed with IA. Methods: Literature search was conducted on PubMed, Google Scholar and Embase. Results: Galactose-α-1,3-galactose (α-gal) allergy, mast cell disorders, and hereditary a-tryptasemia are a few differential diagnoses that should be considered in patients with IA. Unlike food allergy, when anaphylaxis occurs within minutes to 2 hours after allergen consumption, α-gal allergy is a 3-6-hour delayed immunoglobulin E-mediated anaphylactic reaction to a carbohydrate epitope found in red meat (e.g., beef, lamb, pork). The more recently described hereditary α-tryptasemia is an inherited autosomal dominant genetic trait caused by increased germline copies of tryptase human gene alpha-beta 1 (TPSAB1), which encodes α tryptase and is associated with elevated baseline serum tryptase. Acute management of IA consists of carrying an epinephrine autoinjector to be administered immediately at the first signs of anaphylaxis. Long-term management for IA with antihistamines and other agents aims to potentially reduce the frequency and severity of the anaphylactic reactions, although the evidence is limited. Biologics are potentially steroid-sparing for patients with IA; however, more research on IA therapies is needed. Conclusion: The lack of diagnostic criteria, finite treatment options, and intricacies of making a differential diagnosis make IA challenging for patients and clinicians to manage.

Is Oral Food Challenge as Safe Enough as It Seems?

BACKGROUND

Oral food challenges (OFCs) assist in the diagnosis of food allergies and are essential to determine whether an allergy has been outgrown. During the OFC, a medical procedure e introduces foods suspected to be allergenic orally in increasing doses. Mild skin reactions such as urticaria or rarely serious life-threatening reactions such as anaphylaxis may develop.

OBJECTIVE

In this study, we aimed to retrospectively evaluate the clinical and laboratory characteristics of patients who experienced anaphylaxis during open OFCs in a tertiary care children's hospital.

METHODS

Patients who underwent OFCs to confirm the presence of a food allergy or to assess tolerance status at the University of Health Sciences, Ankara, Dr. Sami Ulus Maternity and Children Training and Research Hospital, Pediatric Allergy and Immunology Outpatient Clinic between 1 January 2013 and 1 February 2016, were included in the study. Patients' data were obtained retrospectively from electronic medical records and challenge chart reviews.

RESULTS

A total of 623 OFCs were performed during the period studied. Nine patients (1.4%) between 13 and 67 months of age (mean age: 38.3 months) developed anaphylaxis during their OFC.

CONCLUSION

OFCs should be performed in a hospital or outpatient office under medical supervision that is adequate for anaphylaxis intervention by an allergy specialist. Close observation of objective and subjective symptoms is essential during the challenge because there are no laboratory tests that can predict an anaphylactic diagnosis or the severity of the reaction.

Addressing Common Misconceptions in Food Allergy: A Review

Background: Food allergies are common, affecting 1 in 13 school children in the United States and their prevalence is increasing. Many misconceptions exist with regards to food allergy prevention, diagnosis and management. Objective: The main objective of this review is to address misconceptions with regards to food allergies and discuss the optimal, evidence-based approach for patients who carry this diagnosis. Observations: Common misconceptions in terms of food allergy prevention include beliefs that breastfeeding and delayed introduction of allergenic foods prevent the development of food allergies. In terms of diagnosis, statements such as ‘larger skin prick tests or/and higher levels of food-specific IgE can predict the severity of food-induced allergic reactions’, or ‘Tryptase is always elevated in food-induced anaphylaxis’ are inaccurate. Additionally, egg allergy is not a contraindication for receiving the influenza vaccine, food-allergy related fatalities are rare and peanut oral immunotherapy, despite reported benefits, is not a cure for food allergies. Finally, not all infants with eczema will develop food allergies and epinephrine auto-injectors may unfortunately be both unavailable and underused in food-triggered anaphylaxis. Conclusions and relevance: Healthcare professionals must be familiar with recent evidence in the food allergy field and avoid common misunderstandings that may negatively affect prevention, diagnosis and management of this chronic disease.

Anaphylaxis caused by artisanal honey in a child: a case report

BACKGROUND

Honey is a rare cause of food allergy, especially in children, but it can cause severe systemic allergic reactions. In the pediatric age group, only a few cases have been reported in the literature. Honey allergy may be caused by pollen content or bee-derived proteins. A role for Compositae has been suggested among pollen allergens. Allergology workup of a patient with suspected honey allergy is not well defined. Here we describe a rare case of anaphylaxis in a 5-year-old boy, sensitized to Compositae pollen (ragweed and mugwort), after the ingestion of artisanal honey.

CASE PRESENTATION

The Slavic patient was referred to our hospital emergency department for generalized urticaria and breathing impairment. All the symptoms occurred approximately 30 minutes after the ingestion of a meal containing salmon and artisanal honey. The allergology workup revealed that a skin prick-by-prick test with the implicated artisanal honey was positive, while a variety of different commercial honey and salmon products yielded negative results. Skin prick test and serum-specific immunoglobulin E (IgE) results were also positive for Compositae pollen (ragweed and mugwort). Patients sensitized to weed pollens who ingest bee products may experience an immediate allergic reaction because of the cross-reaction between weed pollens and Compositae bee product pollen. In this case, primary sensitization may be due to airborne Compositae pollen. Commercial honey is heavily processed due to pasteurization and filtration, which removes most of the pollen. These observations highlight the role of Compositae pollen in the observed allergic reaction and suggest that the different pollen content in the artisanal honey relative to commercial honey was responsible for the allergic reaction in our patient.

CONCLUSIONS

This is the first reported pediatric case of honey-induced anaphylaxis in a child under 6 years of age sensitized to Compositae pollen. Pediatricians should be aware of the potential risk of severe allergic reactions upon ingestion of honey and bee products, especially in patients sensitized to weed pollens. To diagnose honey allergy, obtaining a proper clinical history is essential. In addition, skin prick-by-prick tests are helpful, and may represent a simple method to screen for honey allergy in patients sensitized to Compositae pollen, in light of the potential risk.

A severity grading system of food-induced acute allergic reactions to avoid the delay of epinephrine administration

BACKGROUND

Substantial discrepancies among anaphylaxis severity scores may delay epinephrine administration.

OBJECTIVE

The study aims to develop a transparent severity grading system of food-induced acute allergic reactions with a decision model for epinephrine use.

METHODS

The natural course of 315 acute food-induced allergic reactions in children hospitalized at the Allergology department between May 2016 and July 2019 owing to follow-up treatment and allergy diagnostics was evaluated. The severity of episodes was classified according to the 5 most accepted grading systems. The interrater reliability of classification between anaphylaxis severity scores was assessed. All symptoms were grouped into a heat map according to their real-life incidence and clinical relevance. Based on the heat map analysis, a severity grading system of food-induced acute allergic reactions in children with the epinephrine administration decision model was created.

RESULTS

Data from 259 food-induced anaphylaxis episodes in 157 children were included in the analysis. Comparing the grading systems, we observed a 24.7% to 70.2% disagreement between severity scores. The heat map illustrated a strong association between 29 symptoms and their categorization. A new severity grading system was developed and a 2-stage decision model was proposed: "epinephrine yes" (any rapidly progressing symptoms, even mild ones or from 1 organ system; any symptoms from more than 1 organ system; or every grade of anaphylaxis), and "epinephrine available and prepared to use" (nonprogressing mild systemic allergic reaction from 1 system area only; no anaphylaxis).

CONCLUSION

A new severity grading system of food-induced acute allergic reactions in children could serve as a clinical tool for health care professionals to avoid epinephrine administration delay.

Mast Cell Activation During Suspected Perioperative Hypersensitivity: A Need for Paired Samples Analysis

BACKGROUND

Perioperative hypersensitivity (POH) reactions constitute a significant clinical and diagnostic challenge. A transient increase in serum tryptase during POH reflects mast cell activation (MCA) and helps to recognize an underlying hypersensitivity mechanism.

OBJECTIVE

To determine the diagnostic performance of different tryptase decision thresholds based on single and paired measurements to document MCA in suspected POH.

METHODS

Acute serum tryptase (aST) and baseline serum tryptase (bST) samples were obtained from patients referred to our outpatients clinic because of clinical POH. Tryptase samples from controls were obtained before induction (Tt₀) and 1.5 hours after induction (Tt₁) in uneventful anesthesia. Different cutoff points for tryptase increase over bST and the percentage increase in tryptase (%T) were calculated and compared with existing thresholds: aST > [1.2 × (bST) + 2] (consensus formula), aST higher than 11.4 ng/mL, and aST higher than 14 ng/mL.

RESULTS

Patients with POH had higher bST and aST levels compared with controls (respectively 5.15 vs 2.28 ng/mL for bST and 20.30 vs 1.92 ng/mL for aST). The consensus formula and a tryptase increase over bST of greater than or equal to 3.2 ng/mL held the highest accuracies to document MCA in POH (respectively 81% and 82%). A bST of higher than 8 ng/mL was present in 4% of controls, 5% of patients with grade 1 POH, 24% of patients with grade 2 POH, 15% of patients with grade 3 POH, and 17% of patients with grade 4 POH.

CONCLUSIONS

Our data endorse the consensus formula for detection of MCA in POH. Furthermore, it shows that a bST of higher than 8 ng/mL was associated with occurrence of anaphylaxis.

Use and Interpretation of Acute and Baseline Tryptase in Perioperative Hypersensitivity and Anaphylaxis

Paired acute and baseline serum or plasma tryptase sampling and determination have recently been included as a mechanistic approach in the diagnostic and management guidelines of perioperative immediate hypersensitivity and anaphylaxis. The timing of this paired sampling is clearly defined in international consensus statements, with the optimal window for acute tryptase sampling between 30 minutes and 2 hours after the initiation of symptoms, whereas baseline tryptase should be measured in a sample collected before the event (preop) or at least 24 hours after all signs and symptoms have resolved. A transient elevation of the acute tryptase level greater than [2 + (1.2 × baseline tryptase level)] supports the involvement and activation of mast cells. Here, we provide the clinical, pathophysiological, and technical rationale for the procedure and interpretation of paired acute and baseline tryptase. Clinical examples, up-to-date knowledge of hereditary α-tryptasemia as a frequent cause of baseline tryptase of 7 μg/L and higher, mastocytosis, other clonal myeloid disorders, cardiovascular or renal failure, and technical improvements resulting in continued lowering of the 95th percentile value are discussed. Clues for improved management of perioperative immediate hypersensitivity and anaphylaxis include (1) sustained dissemination and implementation of updated guidelines; (2) preoperative sample storage for deferred analysis; (3) referral for thorough allergy investigation, screening for mast cell-related disorders, and recommendations for future anesthetic procedures; and (4) sustained collaboration between anesthesiologists, immunologists, and allergists.

A Case Report of a 3-Year-Old Child With Anaphylactic Shock After a Diclofenac Suppository Confirmed by Serial Tryptase and a Basophil Activation Test

Diclofenac is one of the most commonly used non-steroidal anti-inflammatory drug (NSAID) agents for fever management by general practitioners. Anaphylaxis due to suppository of diclofenac sodium (Voltaren) is extremely rare in children. We report the case of a 3-year-old girl with anaphylactic shock after a diclofenac suppository with confirmation by serial tryptase and a basophil activation test.

Biomarkers for diagnosis and prediction of therapy responses in allergic diseases and asthma

Modern health care requires a proactive and individualized response to diseases, combining precision diagnosis and personalized treatment. Accordingly, the approach to patients with allergic diseases encompasses novel developments in the area of personalized medicine, disease phenotyping and endotyping, and the development and application of reliable biomarkers. A detailed clinical history and physical examination followed by the detection of IgE immunoreactivity against specific allergens still represents the state of the art. However, nowadays, further emphasis focuses on the optimization of diagnostic and therapeutic standards and a large number of studies have been investigating the biomarkers of allergic diseases, including asthma, atopic dermatitis, allergic rhinitis, food allergy, urticaria and anaphylaxis. Various biomarkers have been developed by omics technologies, some of which lead to a better classification of distinct phenotypes or endotypes. The introduction of biologicals to clinical practice increases the need for biomarkers for patient selection, prediction of outcomes and monitoring, to allow for an adequate choice of the duration of these costly and long‐lasting therapies. Escalating healthcare costs together with questions about the efficacy of the current management of allergic diseases require further development of a biomarker‐driven approach. Here, we review biomarkers in diagnosis and treatment of asthma, atopic dermatitis, allergic rhinitis, viral infections, chronic rhinosinusitis, food allergy, drug hypersensitivity and allergen immunotherapy with a special emphasis on specific IgE, the microbiome and the epithelial barrier. In addition, EAACI guidelines on biologicals are discussed within the perspective of biomarkers.

Diagnosis, Classification and Management of Mast Cell Activation Syndromes (MCAS) in the Era of Personalized Medicine

Mast cell activation (MCA) is seen in a variety of clinical contexts and pathologies, including IgE-dependent allergic inflammation, other immunologic and inflammatory reactions, primary mast cell (MC) disorders, and hereditary alpha tryptasemia (HAT). MCA-related symptoms range from mild to severe to life-threatening. The severity of MCA-related symptoms depends on a number of factors, including genetic predisposition, the number and releasability of MCs, organs affected, and the type and consequences of comorbid conditions. In severe systemic reactions, MCA is demonstrable by a substantial increase of basal serum tryptase levels above the individual’s baseline. When, in addition, the symptoms are recurrent, involve more than one organ system, and are responsive to therapy with MC-stabilizing or mediator-targeting drugs, the consensus criteria for the diagnosis of MCA syndrome (MCAS) are met. Based on the etiology of MCA, patients can further be classified as having i) primary MCAS where KIT-mutated, clonal, MCs are detected; ii) secondary MCAS where an underlying IgE-dependent allergy or other reactive MCA-triggering pathology is found; or iii) idiopathic MCAS, where neither a triggering reactive state nor KIT-mutated MCs are identified. Most severe MCA events occur in combined forms of MCAS, where KIT-mutated MCs, IgE-dependent allergies and sometimes HAT are detected. These patients may suffer from life-threatening anaphylaxis and are candidates for combined treatment with various types of drugs, including IgE-blocking antibodies, anti-mediator-type drugs and MC-targeting therapy. In conclusion, detailed knowledge about the etiology, underlying pathologies and co-morbidities is important to establish the diagnosis and develop an optimal management plan for MCAS, following the principles of personalized medicine.

Post mortem tryptase: A review of literature on its use, sampling and interpretation in the investigation of fatal anaphylaxis

Post mortem tryptase is a commonly-used ancillary test in the investigation of possible anaphylactic deaths. Ante mortem tryptase interpretation differs from post mortem interpretation due to differing priorities, biochemical behaviours and capacity for follow-up. Additionally, post mortem tryptase sampling site, method and even cut-off levels are not standardised between facilities. This review of the literature investigates the existing research and recommendations on the use of post mortem tryptase in suspected anaphylactic deaths. Currently, autopsy recommendations suggest early sampling, standardised sampling technique with clamping of and aspiration from the femoral vein, and for the results to be interpreted within the wider autopsy and clinical context. Areas in need of further research include the effects of cytolysis on tryptase levels and studies to stratify differing tryptase levels based on type of death and anaphylactic trigger.

Using Baseline and Peak Serum Tryptase Levels to Diagnose Anaphylaxis: a Review

The diagnosis of anaphylaxis relies on a suggestive clinical history after exposure to a potential triggering factor. Serum tryptase concentrations increase on degranulation of mast cells and therefore serum tryptase levels are measured to diagnose anaphylaxis. There is no standardized method for assessing total serum mast cell tryptase (MCT) in anaphylaxis. The Working Conference in 2010 proposed a consensus equation (peak MCT should be > 1.2x baseline tryptase + 2 ng/L) to diagnose acute mast cell activation (aMCA). Our objective was to narratively review the literature since the Working Conference in 2010, examining the use of the consensus equation and other equations comparing baseline and peak serum tryptase during anaphylaxis. Computerized bibliographic searches of PUBMED and EMBASE were supplemented with a manual search of reference lists. English-language studies were included. Eleven studies met our inclusion criteria with a total of 4551 participants. However, only four studies with 653 participants used the consensus equation. The other seven studies used other methods to compare peak and baseline serum tryptase concentrations. Measuring serum tryptase levels is valuable in the diagnosis of anaphylaxis but is unable to detect all anaphylactic reactions. Based on our current literature review, the consensus equation is underused in the diagnosis of anaphylaxis. There is also a need for exploration of other biomarkers which could be used in parallel to peak and baseline serum tryptase measurements for further diagnostic certainty. Serum tryptase is the most studied biomarker in anaphylaxis but is still far from being the ideal biomarker for this. There is a need to identify new potential useful biomarkers. Serum tryptase levels are valuable in the diagnosis of anaphylaxis, but are unable to detect all anaphylactic reactions. Additionally serial tryptase measurements are laborious in daily clinical practice.

Characteristics and Treatment of Anaphylaxis in Children Visiting a Pediatric Emergency Department in Korea

Anaphylaxis is a serious life-threatening allergic disease in children. This study is aimed at determining the characteristics of pediatric patients who experienced anaphylaxis along with treatments administered in order to determine the usefulness of tryptase level assessment as a marker of anaphylaxis in Korean children. A total of 107 patients who were diagnosed with anaphylaxis in a single pediatric emergency center over a 3-year period were included in the study. Patient clinical characteristics, symptoms, signs, allergy history, trigger factors, treatments, and laboratory findings, including serum tryptase levels, were included in the analysis. Food allergies (39.3%) were the most commonly reported patient allergic history, and 58 patients (54.2%) were triggered by food. Among this group, nuts and milk exposure were the most common, affecting 15 patients (25.9%). History of anaphylaxis and asthma were more common in severe anaphylaxis compared to mild or moderate anaphylaxis cases. Epinephrine intramuscular injection was administrated to 76 patients (71.0%), and a self-injectable epinephrine was prescribed to 18 patients (16.8%). The median tryptase level was 4.80 ng/mL (range: 2.70-10.40) which was lower than the 11.4 ng/mL value commonly documented for standard evaluation in adults with anaphylaxis. The most common cause of pediatric anaphylaxis was food including nuts and milk. The rate of epinephrine injection was relatively high in our pediatric emergency department. The median tryptase level associated with anaphylaxis reactions in children was lower than 11.4 ng/mL. Further studies are needed to help improve diagnostic times and treatment accuracy in pediatric patients who develop anaphylaxis.

Anaphylaxis-a 2020 practice parameter update, systematic review, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) analysis

Anaphylaxis is an acute, potential life-threatening systemic allergic reaction that may have a wide range of clinical manifestations. Severe anaphylaxis and/or the need for repeated doses of epinephrine to treat anaphylaxis are risk factors for biphasic anaphylaxis. Antihistamines and/or glucocorticoids are not reliable interventions to prevent biphasic anaphylaxis, although evidence supports a role for antihistamine and/or glucocorticoid premedication in specific chemotherapy protocols and rush aeroallergen immunotherapy. Evidence is lacking to support the role of antihistamines and/or glucocorticoid routine premedication in patients receiving low- or iso-osmolar contrast material to prevent recurrent radiocontrast media anaphylaxis. Epinephrine is the first-line pharmacotherapy for uniphasic and/or biphasic anaphylaxis. After diagnosis and treatment of anaphylaxis, all patients should be kept under observation until symptoms have fully resolved. All patients with anaphylaxis should receive education on anaphylaxis and risk of recurrence, trigger avoidance, self-injectable epinephrine education, referral to an allergist, and be educated about thresholds for further care.

Anaphylaxis to goat/sheep's milk in a 4-year-old boy tolerant to cow's milk

Immune-mediated reactions to dairy products may vary depending on the mammalian source. We present a case of anaphylaxis to goat/sheep's milk with tolerance to cow's milk. A 4-year-old boy of Eastern European descent presented with gastrointestinal and respiratory symptoms within minutes after eating a goat/sheep's milk-derived food product. The tryptase level measured 1 hour post initial symptoms and 1 month after the allergic reaction were 14.6 µg/L and 5.1 µg/L, respectively (norm: 0.0-13.5 µg/L), confirming the diagnosis of anaphylaxis. A skin prick test performed 1 month after the reaction was highly positive for goat/sheep's milk, but negative for cow's milk. Skin prick tests may establish a life-threatening goat/sheep's milk allergy. Goat/sheep's milk allergy should always be considered in cow's milk-tolerant patients who present with an allergic reaction to dairy products, or when undergoing/have completed of oral immunotherapy for cow's milk allergy.

Perioperative anaphylaxis and investigations: a local study in Hong Kong

INTRODUCTION

Data on local intraoperative anaphylaxis in Hong Kong is scarce, with few reviews available. We aimed to study the characteristics, presentations and workup results of cases referred to a local allergy clinic.

METHODS

A retrospective review was performed of patient referrals and workup results for suspected intraoperative anaphylaxis at Queen Mary Hospital drug allergy clinic in 2012-2016.

RESULTS

Tryptase was checked in only 81.7% (49/60) of the cases, most of which showed elevation (71.4%, 35/49). Among the 59 patients who received a workup, 47 (79.7%) showed positive findings, with a particularly high yield in the tryptase-positive subgroup (88.6%, 31/35). Among the 54 patients who consented to skin tests (the most sensitive investigation), 43 (79.6%) cases were positive. Overall, neuromuscular blockers were the commonest cause (25.0%, 15/60) of intraoperative anaphylaxis, while antibiotics ranked second (23.3%, 14/60). The timing of reactions was an important indication of potential allergens. For example, the majority of the neuromuscular blocker allergies occurred during the induction phase, while all gelofusine allergic events were in the maintenance phase of anaesthesia. 13 (21.7%) out of 60 cases received subsequent general anaesthesia procedures, with no recurrence of allergic reactions.

CONCLUSION

Proper workup after an intraoperative anaphylactic event has a fairly good chance of identifying the causative allergen. These results are useful for patient management and the planning of subsequent anaesthetic procedures.

Chlorpheniramine-induced anaphylaxis: Two case reports and a retrospective review of pharmacovigilance database

RATIONALE

Anaphylaxis is a serious allergic reaction which could be life-threatening. To date, it could be diagnosed by causality between clinical manifestations and triggers. But it is not always easy to find out the clue. Chlorpheniramine maleate (peniramin) is known to safe and it is an antihistamine commonly used to treat almost the whole allergic disease, including urticaria and allergic rhinitis. We recently experienced 2 cases of chlorpheniramine induced anaphylaxis. To document suspected cases of chlorpheniramine-induced adverse reactions, we analyzed a database spontaneously reported adverse drug reactions in the Ajou Regional Pharmacovigilance Center from 2011 to 2017.

PATIENT CONCERNS

Two female patients presented urticaria and abdominal pain right after chlorpheniramine injection.

DIAGNOSES

Both patients were diagnosed with symptoms. One patient confirmed by assistance with tryptase level and another one confirmed cross-reactivity by skin tests.

INTERVENTIONS

One patient was instructed to avoid future administration of chlorpheniramine. The other patient was advised not to take chlorpheniramine, and piperazine derivatives including cetirizine/levocetirizine, but piperidine derivatives such as fexofenadine, loratadine, and ebastine can be available.

OUTCOMES

The patients fully recovered after prompt treatment for anaphylaxis. After that, no recurrences were observed at the following. Among 54 patients with chlorpheniramine-induced adverse drug reactions from the Pharmacovigilance Center database, 17 (31.5%) were reported as anaphylaxis.

LESSONS

Physicians should be aware chlorpheniramine could be a cause for allergic reaction. In addition, we suggest that serum tryptase level, skin prick test, and intradermal test could be considered as a supplementary test for diagnosing chlorpheniramine anaphylaxis and cross-reactivity should also be considered.

Management Strategies Of Idiopathic Anaphylaxis In The Emergency Room: Current Perspectives

Background

Idiopathic anaphylaxis (IA) is a diagnosis of exclusion and represents a major diagnostic and management challenge. There are no current guidelines for diagnosis and management of IA. We aim to present a systematic review of the literature on adult and pediatric IA.

Methods

We conducted a systematic review of original articles published in the past 22 years regarding diagnosis and management strategies of adult and pediatric IA.

Results

The current proposed diagnostic approach and treatment regimens are based on a few small studies. Future large-scale studies are required. IA is a diagnosis of exclusion and should be made only after extensive evaluation excludes potential anaphylaxis triggers as well as non-allergic conditions with a similar presentation. There is currently no diagnostic consensus for IA. Furthermore, the current proposed treatment regimens are limited and rely on prophylactic treatment with antihistamines and prednisone for patients with frequent episodes. However, daily treatment with systemic steroids has well-recognized serious adverse effects. More recently, the use of biologics was suggested to benefit patients with IA, although the optimal management protocol is not yet established.

Conclusion

Future studies are needed to optimize diagnosis and treatment strategies in adult and pediatric cases of IA. Omalizumab may be a promising novel therapeutic option for adult and pediatric IA.

Idiopathic anaphylaxis yardstick: Practical recommendations for clinical practice

Anaphylaxis is considered idiopathic when there is no known trigger. The signs and symptoms of idiopathic anaphylaxis (IA) are identical to those of anaphylaxis because of a known cause and can include cutaneous, circulatory, respiratory, gastrointestinal, and neurologic symptoms. Idiopathic anaphylaxis can be a frustrating disease for patients and health care providers. Episodes are unpredictable, and differential diagnosis is challenging. Current anaphylaxis guidelines have little specific guidance regarding differential diagnosis and long-term management of IA. Therefore, the objective of the Idiopathic Anaphylaxis Yardstick is to use published data and the authors' combined clinical experience to provide practical recommendations for the diagnosis and management of patients with IA.

Serum Baseline Tryptase Level as a Marker for the Severity of Anaphylaxis

BACKGROUND

Anaphylaxis is a severe and potentially fatal allergic disease or hypersensitivity reaction with variable clinical presentation. Biomarkers in anaphylaxis could be useful to improve diagnosis, to allow endotyping of patients, and to predict risk.

OBJECTIVE

To investigate the role of serum basal tryptase (sBT) levels in the management of patients with anaphylaxis.

METHODS

Patients with at least 1 episode of anaphylaxis were selected among those who attended the Allergy Clinics of the Clinical Hospital of the Ribeirão Preto Medical School, University of São Paulo, Brazil, upon evaluation by allergy/immunology specialists of our medical staff. Demographic and clinical data were obtained using a structured questionnaire. sBT levels were determined using the ImmunoCAP Tryptase immunoassay.

RESULTS

57 patients (56.1% female) with a median age of 35 years (range 7-87 years) participated in the study. sBT levels ranged from 2.57 to 21.19 ng/mL (mean 5.17 ng/mL), with no significant differences in patients with anaphylaxis due to different triggers. Mean levels were 4.93; 5.2; 5.41, and 5.24 ng/mL for patients who had anaphylaxis due to Hymenoptera venom (n = 17), foods (n = 13), drugs (n = 13), and idiopathic disease (n = 14), respectively. Significantly higher sBT levels were observed in patients with severe anaphylaxis (grade IV) than in patients with mild-moderate disease (grades II/III) (mean levels 6.61 vs. 4.71 ng/mL, respectively).

CONCLUSION

High sBT levels may help to identify patients at increased risk of more severe anaphylaxis, prompting physicians to initiate immediate therapy to avoid further acute episodes.

Why the 20% + 2 Tryptase Formula Is a Diagnostic Gold Standard for Severe Systemic Mast Cell Activation and Mast Cell Activation Syndrome

Mast cell activation syndrome (MCAS) is a condition characterized by recurrent episodes of clinically relevant, systemic, severe reactions to mast cell (MC)-derived mediators released in the context of anaphylaxis or another acute MC-related event. It is important to document MC involvement in these reactions in order to establish the diagnosis MCAS. The most specific and reliable marker of systemic MC activation is an acute and substantial event-related (transient) increase in the serum tryptase level over the individual's baseline value. However, the baseline level of tryptase varies depending on the underlying disease and the genetic background. For example, an estimated 3-5% of healthy individuals exhibit duplications or multiple copies of the TPSAB1 gene encoding for alpha-tryptase, and over 30% of all patients with myeloid neoplasms, including mastocytosis, have elevated basal tryptase levels. Therefore, it is of utmost importance to adjust the event-related diagnostic (MCAS-confirming) increase in tryptase over the individual baseline in a robust approach. To address this challenge, the 20% + 2 formula was proposed by the consensus group in 2012. Since then, this approach has been validated in clinical practice by independent groups and found to be sound. In the current article, we discuss the emerging importance and value of the 20% + 2 formula in clinical practice and its role as a criterion of severe systemic MC activation and MCAS.

Myths, facts and controversies in the diagnosis and management of anaphylaxis

Anaphylaxis is a serious systemic allergic reaction that is rapid in onset and may cause death. Despite numerous national and international guidelines and consensus statements, common misconceptions still persist in terms of diagnosis and appropriate management, both among healthcare professionals and patient/carers. We address some of these misconceptions and highlight the optimal approach for patients who experience potentially life-threatening allergic reactions.

Recent developments and highlights in biomarkers in allergic diseases and asthma

The potential of precision medicine in allergy and asthma has only started to be explored. A significant clarification in the pathophysiology of rhinitis, chronic rhinosinusitis, asthma, food allergy and drug hypersensitivity was made in the last decade. This improved understanding led to a better classification of the distinct phenotypes and to the discovery of new drugs such as biologicals, targeting phenotype-specific mechanisms. Nevertheless, many conditions remain poorly understood such as non-eosinophilic airway diseases or non-IgE-mediated food allergy. Moreover, there is a need to predict the response to specific therapies and the outcome of drug and food provocations. The identification of patients at risk of progression towards severity is also an unmet need in order to establish adequate preventive or therapeutic measures. The implementation of precision medicine in the clinical practice requires the identification of phenotype-specific markers measurable in biological matrices. To become useful, these biomarkers need to be quantifiable by reliable systems, and in samples obtained in an easy, rapid and cost-efficient way. In the last years, significant research resources have been put in the identification of valid biomarkers for asthma and allergic diseases. This review summarizes these recent advances with focus on the biomarkers with higher clinical applicability.

Evaluation of the left venticular systolic function with the measurement of global longitudinal strain by Speckle tracking echocardiography in anaphylaxis

Background

It is not known how cardiac functions are affected during anaphylaxis.

Objective

Our aim was to measure the cardiac functions shortly after an anaphylaxis attack using a new technique that detects subclinical left ventricular dysfunction.

Methods

Patients in our hospital who experienced anaphylaxis and urticaria (control group) due to any cause were included in the study. Tryptase levels were measured on the third hour of the reaction and 6 weeks later. Left ventricular systolic functions were evaluated with global strain measurement using echocardiography, approximately 4 hours and 6-week post reaction.

Results

Twelve patients were included in the anaphylaxis group (83.3% female; mean age, 43.25 ± 9.9 years). The causes of anaphylaxis were drug ingestion (n = 11) and venom immunotherapy. Eight of the anaphylactic reactions (66.7%) were severe and in 9 reactions (75%) tryptase levels increased. In the anaphylaxis group, strain values measured shortly after anaphylaxis were significantly lower than those calculated 6 weeks later (p < 0.001) and tryptase levels significantly increased (p = 0.002). The strain values measured both shortly after anaphylaxis and 6 weeks later did not differ according to severity of anaphylaxis. In severe anaphylaxis, tryptase levels during anaphylaxis and 6 weeks later were significantly higher (p = 0.019, p = 0.035). The control group evidenced no differences regarding strain and tryptase levels measured at reaction and 6 weeks later. At reaction, in the anaphylaxis group, the tryptase levels were higher and the strain values were lower than those in the urticaria group (p = 0.007, p = 0.003).

Conclusion

Cardiac dysfunction may develop during an anaphylaxis independent of severity of reaction.

Anaphylaxis and Clinical Utility of Real-World Measurement of Acute Serum Tryptase in UK Emergency Departments

BACKGROUND

British guidelines recommend that serial acute serum tryptase measurements be checked in all adults and a subset of children presenting with anaphylaxis. This is the first study reporting the clinical utility of acute serum tryptase in a "real-world" emergency department (ED) setting following the publication of the World Allergy Organization (WAO) criteria for anaphylaxis.

OBJECTIVES

To (1) assess sensitivity, specificity, and positive and negative predictive values (PPV, NPV) of acute serum tryptase in anaphylaxis; (b) determine factors associated with higher acute serum tryptase levels; and (c) audit compliance of acute serum tryptase measurement in the ED.

METHODS

The methods used were retrospective electronic search for ED admissions to 3 acute care hospitals in Birmingham, UK, with anaphylaxis in 2012 using wide search terms followed by scrutiny of electronic clinical records and application of the WAO diagnostic criteria for anaphylaxis. Patients with an acute serum tryptase measurement were included in the analysis.

RESULTS

Acute serum tryptase level was measured in 141 of 426 (33.1%) cases. Mean time from the onset of symptoms to the measurement of acute serum tryptase level was 4 hours 42 minutes (SD ± 05:03 hours) and no patients had serial measurements conforming to British guidelines. Acute serum tryptase level of more than 12.4 ng/mL (75th centile) was associated with a sensitivity, specificity, PPV, and NPV of 28%, 88%, 0.93, and 0.17, respectively. Multiple regression analysis showed that male sex (odds ratio, 2.66; P = .003) and hypotension (odds ratio, 7.08; P = .001) predicted higher acute serum tryptase level.

CONCLUSIONS

An acute serum tryptase level of more than 12.4 ng/mL in an ED setting carries high PPV and specificity, but poor sensitivity and NPV.

In Vitro Diagnosis of Immediate Drug Hypersensitivity Anno 2017: Potentials and Limitations

Background

For most physicians, quantification of drug-specific immunoglobulin E (drug-sIgE) antibodies constitutes the primary in vitro measure to document immediate drug hypersensitivity reactions (IDHR). Unfortunately, this is often insufficient to correctly identify patients with IgE-mediated IDHR and impossible for non-IgE-mediated IDHR that result from alternative routes of basophil and mast cell activation. In these difficult cases, diagnosis might benefit from cellular tests such as basophil activation tests (BAT).

Aim

The aim was to review the potential and limitations of quantification of sIgE and BAT in diagnosing IDHR. The utility of quantification of serum tryptase is discussed.

Methods

A literature search was conducted using the key words allergy, basophil activation, CD63, CD203c, diagnosis, drugs, hypersensitivity, flow cytometry, specific IgE antibodies; this was complemented by the authors’ own experience.

Results

The drugs that have been most studied with both techniques are β-lactam antibiotics and curarizing neuromuscular blocking agents (NMBA). For sIgE morphine, data are available on the value of this test as a biomarker for sensitization to substituted ammonium structures that constitute the major epitope of NMBA, especially rocuronium and suxamethonium. For the BAT, there are also data on non-steroidal anti-inflammatory drugs (NSAIDs) and iodinated radiocontrast media. For β-lactam antibiotics, sensitivity and specificity of sIgE varies between 0 and 85% and 52 and 100%, respectively. For NMBA, sensitivity and specificity varies between 38.5 and 92% and 85.7 and 100%, respectively. Specific IgE to morphine should not be used in isolation to diagnose IDHR to NMBA nor opiates. For the BAT, sensitivity generally varies between 50 and 60%, whereas specificity attains 80%, except for quinolones and NSAIDs.

Conclusions

Although drug-sIgE assays and BAT can provide useful information in the diagnosis of IDHR, their predictive value is not absolute. Large-scale collaborative studies are mandatory to harmonize and optimize test protocols and to establish drug-specific decision thresholds.

Food allergy and atopic dermatitis: Prediction, progression, and prevention

The rising burden of allergic diseases in childhood requires a compelling need to identify individuals at risk for atopy very early in life or even predict the onset of food allergy and atopic dermatitis since pregnancy. The development and clinical phenotypes of atopic diseases in childhood depend on a complex interaction between genetic and environmental factors, such as allergen exposure, air pollution, and infections. Preventive strategies may include avoidance measures, diet supplements, and early complementary food introduction. Overall, the management of allergic diseases has been improving to date toward a patient's tailored approach. This review will cover the current understanding of risk factors, prediction, and management of food allergy and atopic dermatitis in childhood and discuss how these may contribute to the modification of the natural history of food allergy and atopic dermatitis.

The pathophysiology of anaphylaxis

Anaphylaxis is a severe systemic hypersensitivity reaction that is rapid in onset; characterized by life-threatening airway, breathing, and/or circulatory problems; and usually associated with skin and mucosal changes. Because it can be triggered in some persons by minute amounts of antigen (eg, certain foods or single insect stings), anaphylaxis can be considered the most aberrant example of an imbalance between the cost and benefit of an immune response. This review will describe current understanding of the immunopathogenesis and pathophysiology of anaphylaxis, focusing on the roles of IgE and IgG antibodies, immune effector cells, and mediators thought to contribute to examples of the disorder. Evidence from studies of anaphylaxis in human subjects will be discussed, as well as insights gained from analyses of animal models, including mice genetically deficient in the antibodies, antibody receptors, effector cells, or mediators implicated in anaphylaxis and mice that have been "humanized" for some of these elements. We also review possible host factors that might influence the occurrence or severity of anaphylaxis. Finally, we will speculate about anaphylaxis from an evolutionary perspective and argue that, in the context of severe envenomation by arthropods or reptiles, anaphylaxis might even provide a survival advantage.

A national survey of Russian physicians' knowledge of diagnosis and management of food-induced anaphylaxis

OBJECTIVES

Food allergy is an increasing burden worldwide and is a common problem within paediatric populations, affecting 5%-8% of children. Anaphylaxis caused by food proteins is a potentially life-threatening condition and all healthcare practitioners should be aware of its recognition and management. Russia is the largest country in Europe but it is still unknown whether physicians are prepared to diagnose and manage food-induced anaphylaxis effectively. We aimed to examine physicians' knowledge of diagnosis and management of food-induced anaphylaxis.

SETTING, POPULATION AND OUTCOMES

A survey was designed and published online at VrachiRF.ru website (for registered Russian-speaking practicing physicians). We obtained information on respondents' clinical settings, experience and specialty. Survey questions were based on a characteristic clinical scenario of anaphylaxis due to food ingestion. Outcome measures consisted of correct answers to the anaphylaxis diagnosis and management questions.

RESULTS

From a total of 707 of physicians accessed in the survey, 315 (45%) responded to the clinical scenario. 16 respondents reported training in allergy-immunology and have been excluded from the analysis, leaving the final sample size of 299. Respondents were paediatricians (68%) and other specialties adult physicians (32%). Overall, 100 (33%) of respondents diagnosed anaphylaxis, but only 29% of those making the correct diagnosis administered adrenalin (1:1000) intramuscular. Respondents working in secondary/tertiary clinics diagnosed anaphylaxis significantly more often (p=0.04) when compared with primary care/private practice physicians. This difference was also apparent as the most important influence on responses in the multivariate analysis.

CONCLUSIONS

In this national sample of Russian physicians, we found poor knowledge in both anaphylaxis diagnosis and management. Our data show that the chance of being properly diagnosed with anaphylaxis is 33% and being appropriately treated with adrenalin is 10%. These findings highlight lack of anaphylaxis knowledge among Russian physicians, both paediatricians and other specialists and illustrates the urgent need for allergy/anaphylaxis training.

In Vitro Research Tools in the Field of Human Immediate Drug Hypersensitivity and Their Present Use in Small Animal Veterinary Medicine

Drug hypersensitivity reactions (DHR) are immune-mediated idiosyncratic adverse drug events. Type I DHR are often referred to as "immediate" and involve B lymphocyte-secreted IgE that bind to the membrane of basophils and mast cells, inducing their degranulation. This review presents various in vitro tests that were developed in the field of human type I HS and implemented as clinical diagnostic tools in human cases of immediate DHR. The respective strengths and weaknesses of each test will be discussed in parallel of validation data such as specificity and sensitivity whenever available. Some of them have also been used as diagnostic tools in veterinary medicine, but not in cases of immediate DHR. Most of these diagnostic tools can be categorized into humoral and cellular tests. The former tests measure serum concentrations of factors, such as histamine, tryptase, and drug-specific IgE. The latter assays quantify markers of drug-induced basophil activation or drug-specific lymphocyte proliferation. Pharmacogenetic markers have also been investigated in immediate DHR, but not as extensively as in non-immediate ones. Throughout, practical aspects and limitations of the tests, as well as sensitivity and specificity parameters, will be presented. In addition, the experience of veterinary medicine with these diagnostic tools will be summarized. However, to date, none of them has ever been reported in a veterinary case of type I DHR.