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

Relationship between Tryptase and Hypotension in Anaphylaxis during Anesthesia

INTRODUCTION

Hypotension is a cardiovascular symptom that appears at the onset of anaphylaxis. It is considered an important factor as it affects the severity of anaphylaxis; however, its details remain to be elucidated. In this study, we investigated the characteristics of hypotension at the onset of anaphylaxis during anesthesia, along with the relationship between hypotension, tryptase and histamine.

MATERIALS AND METHODS

The minimum systolic blood pressures of patients diagnosed with anaphylaxis using the clinical diagnostic criteria of the World Allergy Organization guidelines were extracted from electronic anesthesia records. We analyzed changes in tryptase and histamine that were measured after the onset of anaphylaxis. We analyzed the relationship of tryptase and histamine with the minimum systolic blood pressure and the severity of anaphylaxis.

RESULTS

Of 55,996 patients, 25 were diagnosed with anaphylaxis during anesthesia (0.045%). Among these patients, the minimum systolic blood pressure was less than 90 mmHg. Furthermore, the minimum systolic blood pressure was inversely correlated with tryptase levels immediately to 1 hour, and 2 to 4 hours after the onset of anaphylaxis. The minimum systolic blood pressure was inversely correlated with the severity of anaphylaxis. The severity of anaphylaxis was positively correlated with tryptase levels immediately to 1 hour, and 2 to 4 hours after the onset of anaphylaxis.

CONCLUSION

Hypotension tended to reflect the severity of anaphylaxis. Tryptase is an adjunct in the diagnosis of hypotension and may be a useful indicator of the severity of anaphylaxis. A larger-scale study is needed to validate these results.

Remimazolam-Induced Anaphylaxis and Cardiovascular Collapse: A Narrative Systematic Review of Eleven Cases

Background and Objectives: Remimazolam, a novel benzodiazepine, is used for procedural sedation and general anesthesia due to its rapid onset and short duration of action. However, remimazolam-induced anaphylaxis (RIA) is a rare but severe complication. This study aimed to analyze RIA characteristics, focusing on cardiovascular collapse, and provide guidelines for safe remimazolam use. Methods: This study conducted a systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Research articles retrieved from PubMed on 26 May 2023, using the keywords 'remimazolam AND anaphylaxis' were evaluated based on the inclusion criteria of being written in English and aligning with the World Allergy Organization criteria for anaphylaxis, while studies not meeting these criteria were excluded. All published articles up to the search date were included without any date restrictions. The review analyzed factors such as age, sex, type of anesthesia, remimazolam dose (bolus/continuous), allergic symptoms and sign, epinephrine use, serum tryptase levels, and skin prick tests. Results: Among eleven cases, the mean age was 55.6 ± 19.6 years, with 81.8% male. Hypotension (81.8%) was the most common symptom, followed by bradycardia (54.5%) and desaturation (36.4%). Two patients experienced cardiac arrest. Serum tryptase levels confirmed anaphylaxis in ten cases. Epinephrine was the primary treatment, with intravenous doses ranging from 0.1 mg to 0.3 mg. Conclusions: Vigilance is crucial when administering remimazolam, adhering to recommended dosages, and promptly treating RIA with epinephrine. Further research is needed to understand the risk factors and refine the management strategies. Guidelines for safe remimazolam use are proposed.

Identifying patients at risk of anaphylaxis

Anaphylaxis is an acute, potentially fatal, systemic hypersensitivity reaction that warrants prompt diagnosis and management. It continues to be challenging to anticipate who may be at risk of a severe, life-threatening allergic reaction. Anaphylaxis can be caused by a range of allergens, such as certain foods, medications, latex, insect stings, etc. Cofactors that augment the severity of clinical symptoms and increase the risk of poor outcomes include exercise, stress, infectious diseases, underlying mast cell disease, active allergic disease such as asthma, advanced age, intake of certain medications, history of previous anaphylaxis, and delayed or missed administration of adrenaline. According to the European Anaphylaxis Registry, food is the major elicitor of anaphylaxis, especially eggs, cow milk, and nuts, in children and adolescents. Reaction to insect venom has also been noted in young adulthood. Early recognition of signs and symptoms and prompt treatment are crucial in anaphylaxis management to avoid serious and even fatal outcomes. It is crucial for both individuals and clinicians to identify the cause of anaphylaxis. Biomarkers of anaphylaxis, such as histamine, tryptase, platelet activation factor (PAF), chymase, carboxypeptidase A3, dipeptidyl peptidase I (DPPI), basogranulin, CCL-2, hsa-miR-451a, may be useful in diagnosis and management. The purpose of this review article is to present a comprehensive overview of current evidence and expert opinions regarding the risk factors that predispose individuals to anaphylaxis. Additionally, it provides insights into potential biomarkers and genetic markers for accurate diagnosis and management. This review underscores the significance of expert guidance in enhancing patient outcomes and enabling self-management of anaphylactic episodes.

Short-term biological variation of serum tryptase

OBJECTIVES

Serum tryptase is a biomarker of mast cell activation. Among others, it is used in the diagnosis of anaphylaxis where a significant increase during the acute phase supports the diagnosis. When evaluating changes in biomarker levels, it is of utmost importance to consider the biological variation of the marker. Therefore, the aim of this study was to evaluate the short-term biological variation of serum tryptase.

METHODS

Blood samples were drawn at 9 AM three days in a row from apparently healthy subjects. On day two, additional blood samples were drawn every third hour for 12 h. The tryptase concentration was measured in serum using a fluoroenzyme immunoassay (ImmunoCAP™, Thermo Fisher Scientific). Linear mixed-effects models were used to calculate components of biological variation.

RESULTS

In 32 subjects, the overall mean concentration of tryptase was 4.0 ng/mL (range, 1.3-8.0 ng/mL). The within-subject variation was 3.7 % (95 % confidence interval (CI) 3.0-4.4 %), the between-subject variation was 31.5 % (95 % CI 23.1-39.8 %), and the analytical variation was 3.4 % (95 % CI 2.9-4.1 %). The reference change value was 13.3 % for an increase in tryptase at a 95 % level of significance. No significant day-to-day variation was observed (p=0.77), while a minute decrease in the serum concentration was observed during the day (p<0.0001).

CONCLUSIONS

Serum tryptase is a tightly regulated biomarker with very low within-subject variation, no significant day-to-day variation, and only minor semidiurnal variation. In contrast, a considerable between-subject variation exists. This establishes serum tryptase as a well-suited biomarker for monitoring.

Safety and anti-tumour activity of the IgE antibody MOv18 in patients with advanced solid tumours expressing folate receptor-alpha: a phase I trial

All antibodies approved for cancer therapy are monoclonal IgGs but the biology of IgE, supported by comparative preclinical data, offers the potential for enhanced effector cell potency. Here we report a Phase I dose escalation trial (NCT02546921) with the primary objective of exploring the safety and tolerability of MOv18 IgE, a chimeric first-in-class IgE antibody, in patients with tumours expressing the relevant antigen, folate receptor-alpha. The trial incorporated skin prick and basophil activation tests (BAT) to select patients at lowest risk of allergic toxicity. Secondary objectives were exploration of anti-tumour activity, recommended Phase II dose, and pharmacokinetics. Dose escalation ranged from 70 μg-12 mg. The most common toxicity of MOv18 IgE is transient urticaria. A single patient experienced anaphylaxis, likely explained by detection of circulating basophils at baseline that could be activated by MOv18 IgE. The BAT assay was used to avoid enrolling further patients with reactive basophils. The safety profile is tolerable and maximum tolerated dose has not been reached, with evidence of anti-tumour activity observed in a patient with ovarian cancer. These results demonstrate the potential of IgE therapy for cancer.

Anaphylaxis after consumption of wasp larvae in Reunion Island: a case report

The practice of entomophagy is common in Asia, Africa, and South America and is now spreading to Europe and the United States. Entomophagy is not without risk since humans can develop allergic reactions to the ingested insects. Here we describe a case of anaphylaxis after consumption of Polistes olivaceus larvae in a 23-y-old man living in Reunion Island, a French overseas department where wasps and other insects are occasionally consumed as part of local traditions. The patient developed diffuse pruritus with facial edema, nausea, and vomiting 15 min after ingesting pan-fried wasp larvae during a dinner with two other people. He was taken to a local care center where he received two oral doses of antihistamines. Shortly after, he presented with shock and hemodynamic, respiratory, and neurological failure. He received a subcutaneous injection of adrenaline and was rapidly transferred to hospital for 12 h of monitoring, after which he was discharged without sequelae. The patient's anaphylactic reaction may have been due only to the allergens contained in the ingested larvae or to cross-allergy. To our knowledge, this is the first reported case of anaphylaxis after consumption of Polistes olivaceus larvae. More generally, few cases of allergic reaction to ingested insects have been described in the literature.

Not all Shock States Are Created Equal: A Review of the Diagnosis and Management of Septic, Hypovolemic, Cardiogenic, Obstructive, and Distributive Shock

Shock in the critically ill patient is common and associated with poor outcomes. Categories include distributive, hypovolemic, obstructive, and cardiogenic, of which distributive (and usually septic distributive) shock is by far the most common. Clinical history, physical examination, and hemodynamic assessments & monitoring help differentiate these states. Specific management necessitates interventions to correct the triggering etiology as well as ongoing resuscitation to maintain physiologic milieu. One shock state may convert to another and may have an undifferentiated presentation; therefore, continual re-assessment is essential. This review provides guidance for intensivists for management of all shock states based on available scientific evidence.

An interdisciplinary approach to characterize peanut-allergic patients-First data from the FOOD@ consortium

Background

Peanut allergy is a frequent cause of food allergy and potentially life‐threatening. Within this interdisciplinary research approach, we aim to unravel the complex mechanisms of peanut allergy. As a first step were applied in an exploratory manner the analysis of peanut allergic versus non‐allergic controls.

Methods

Biosamples were studied regarding DNA methylation signatures, gut microbiome, adaptive and innate immune cell populations, soluble signaling molecules and allergen‐reactive antibody specificities. We applied a scalable systems medicine computational workflow to the assembled data.

Results

We identified combined cellular and soluble biomarker signatures that stratify donors into peanut‐allergic and non‐allergic with high specificity. DNA methylation profiling revealed various genes of interest and stool microbiota differences in bacteria abundances.

Conclusion

By extending our findings to a larger set of patients (e.g., children vs. adults), we will establish predictors for food allergy and tolerance and translate these as for example, indicators for interventional studies.

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.

Characterization of hypersensitivity reactions to polysulfone hemodialysis membranes

BACKGROUND

In recent years, cases have been reported in which unexpected systemic hypersensitivity reactions occurred in patients dialyzed with polysulfone- or polyethersulfone-biocompatible membranes in the absence of other risk factors. The pathomechanisms involved in these reactions are largely unknown.

OBJECTIVE

To characterize hypersensitivity reactions to polysulfone hemodialysis using clinical and laboratory data and to identify biomarkers suitable for endotype identification and diagnosis.

METHODS

We prospectively collected data from 29 patients with suspected hypersensitivity reactions to polysulfone hemodialysis membranes. Clinical laboratory parameters such as tryptase, blood cell counts, and complement levels were recorded. Acute samples were obtained from 18 cases for the ex vivo assessment of basophil activation by flow cytometry analysis of CD63, CD203, and FcεRI cell membrane expression. Serum cytokines and anaphylatoxin concentrations were evaluated in 16 cases by Luminex and cytometric bead array analysis.

RESULTS

Tryptase was elevated during the acute reaction in 4 cases. Evidence of basophil activation was obtained in 10 patients. Complement activation was found in only 2 cases. However, C5a serum levels tended to increase during the acute reaction in those patients with hypoxemia. Significantly higher serum levels of interleukin-6 were observed during the acute reactions to polysulfone hemodialysis (P = .0103).

CONCLUSION

Based on biomarker analysis, various endotypes were identified, including type I-like (with the involvement of mast cells or basophils), complement, and cytokine (interleukin-6) release-related reactions, with some patients showing mixed reactions. Further research is needed to unravel the exact mechanisms involved in the activation of these cellular and molecular pathways.

Fish Roe-Induced Anaphylaxis in Italy: A Pediatric Case Report

Fish roe are not yet described as triggers of allergic reactions in Italy, especially during the pediatric age; they are more frequently involved in anaphylaxis in Eastern countries, such as Japan. For this report, we reported a case of anaphylaxis in a 2-year-old boy admitted to our Hospital Pediatric Emergency Room with a suspected allergic reaction. 15 min after the meal, he presented generalized urticaria, angioedema, wheezing, sneezing, and two vomiting episodes. The meal was smoked salmon, butter, mayonnaise, anchovies, and fish roe (salmon and lumpfish roe). Tryptase serum levels presented as elevated in the acute phase and normal after 24 h. Serum food-specific IgE tested negative for salmon and other fish, such as skin prick tests. Serum food-specific IgE showed that the patient was sensitized to cow's milk and eggs, but he doesn't have a food allergy. He had regularly consumed milk and eggs before and after the allergic reaction without clinical problems. A prick-by-prick test resulted positive for fish roe (salmon and lumpfish roe). Based on patient's history, allergy test results in vivo, and tryptase serum levels, the diagnosis of anaphylaxis induced by fish roe was confirmed. In conclusion, to the best of our knowledge, this is the first pediatric case of fish roe-induced anaphylaxis reported in Italy.

Applying lessons learned from nanomedicines to understand rare hypersensitivity reactions to mRNA-based SARS-CoV-2 vaccines

After over a billion of vaccinations with messenger RNA-lipid nanoparticle (mRNA-LNP) based SARS-CoV-2 vaccines, anaphylaxis and other manifestations of hypersensitivity can be considered as very rare adverse events. Although current recommendations include avoiding a second dose in those with first-dose anaphylaxis, the underlying mechanisms are unknown; therefore, the risk of a future reaction cannot be predicted. Given how important new mRNA constructs will be to address the emergence of new viral variants and viruses, there is an urgent need for clinical approaches that would allow a safe repeated immunization of high-risk individuals and for reliable predictive tools of adverse reactions to mRNA vaccines. In many aspects, anaphylaxis symptoms experienced by the affected vaccine recipients resemble those of infusion reactions to nanomedicines. Here we share lessons learned over a decade of nanomedicine research and discuss the current knowledge about several factors that individually or collectively contribute to infusion reactions to nanomedicines. We aim to use this knowledge to inform the SARS-CoV-2 lipid-nanoparticle-based mRNA vaccine field.

Estimating the within‐subject (CV I ) and between‐subject (CV G ) biological variation of serum tryptase

Background

Methods

Results

Conclusions

Serological profiling reveals hsa-miR-451a as a possible biomarker of anaphylaxis

Background

There is a need to support the diagnosis of anaphylaxis by objective markers. miRNAs are promising noncoding RNA species that may serve as serological biomarkers, but their use in diagnosing anaphylaxis has not been systematically studied to our knowledge. We aimed to comprehensively investigate serum biomarker profiles (proteins, lipids, and miRNAs) to support the diagnosis of anaphylaxis.

Methods

Adult patients admitted to the emergency room with a diagnosis of anaphylaxis (<3 hours) were included. Blood samples were taken upon emergency room arrival and 1 month later.

Results

Next-generation sequencing of 18 samples (6 patients with anaphylaxis in both acute and nonacute condition, for 12 total samples, and 6 healthy controls) identified hsa-miR-451a to be elevated during anaphylaxis, which was verified by quantitative real-time PCR in the remaining cohort. The random forest classifier enabled us to classify anaphylaxis with high accuracy using a composite model. We identified tryptase, 9α,11β-PGF2, apolipoprotein A1, and hsa-miR-451a as serological biomarkers of anaphylaxis. These predictors qualified as serological biomarkers individually but performed better in combination.

Conclusion

Unexpectedly, hsa-miR-451a was identified as the most relevant biomarker in our data set. We were also able to distinguish between patients with a history of anaphylaxis and healthy individuals with higher accuracy than any other available model. Future studies will need to verify miRNA biomarker utility in real-life clinical settings.

Funding

This work is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) as part of the clinical research unit (CRU339): Food Allergy and Tolerance (FOOD@) (project number 409525714) and a grant to MW (Wo541-16-2, project number 264921598), as well as by FOOD@ project numbers 428094283 and 428447634.

New Biomarkers in Anaphylaxis (Beyond Tryptase)

Purpose of Review

The purpose of this review is to provide a better understanding of anaphylaxis pathophysiology and describe the underlying mechanisms, effector cells, and the potential biomarkers involved depending on the anaphylaxis endotypes.

Recent Findings

New insight into the potential relevance of pathways others than IgE-dependent anaphylaxis has been unraveled, as well as other biomarkers than tryptase, such as the role of platelet activation factor, basogranulin, dipeptidyl peptidase I, CCL-2, and other cytokines.

Summary

Gaining knowledge of all the mediators and cellular activation/communication pathways involved in each endotype of anaphylaxis will allow the application of precision medicine in patients with anaphylactic reactions, providing insights to the most appropriate approach in each case and helping to stratify severity and risk prediction.

Optimizing tools for evaluating challenge outcomes in children with cashew nut allergy

BACKGROUND

The incidence of cashew nut anaphylaxis is increasing and there is a need for accurate diagnostic tests. Age-specific cutoffs in children are lacking. Changes in serum tryptase levels are not well documented in pediatric food allergy, except in anaphylaxis.

OBJECTIVE

To evaluate the ability of various tests to diagnose cashew nut allergy and to predict reaction severity. We also investigated changes in tryptase and their correlation to reaction severity.

METHODS

We performed an open cashew nut challenge on 106 children (aged 1-16 years), who were sensitized to cashew nut with either previous allergic reaction to cashew nut or no known exposure. We analyzed the accuracy of Ana o 3 immunoglobulin E (IgE), cashew nut IgE, skin prick test, basophil activation test (BAT), and combinations thereof to diagnose cashew nut allergy and to predict reaction severity. Tryptase level was measured at the baseline and during an allergic reaction.

RESULTS

A total of 72 children had positive challenge outcomes. Ana o 3 IgE seemed to be the best single test to diagnose cashew allergy, with a 0.97 kU/L cutoff exhibiting 94.1% specificity and 61.1% sensitivity. Though BAT values of at least 22.8% best predicted reaction severity, with 91.7% specificity and 60.7% sensitivity, the cutoffs were age-specific. Tryptase levels increased substantially 1 to 2 hours after the first allergic symptoms compared with baseline.

CONCLUSION

Ana o 3 IgE seems to be the best diagnostic test in pediatric cashew nut allergy, and test combinations do not seem to improve the diagnostics. Cutoffs are age-specific. BAT is promising in predicting reaction severity. Tryptase levels should be measured 1 to 2 hours after initiation of an allergic reaction.

Low risk of contrast media-induced hypersensitivity reactions in all subtypes of systemic mastocytosis

BACKGROUND

Patients with systemic mastocytosis (SM) are at increased risk of hypersensitivity reactions (HRs). Although Hymenoptera venoms are the predominant triggers, cases of contrast media-induced HR (CMIHR) have also been reported and prophylactic premedication is often performed. However, data from larger series are limited and differences between indolent and advanced SM have not yet been investigated.

OBJECTIVE

To determine the incidence and severity of CMIHR in all subtypes of SM.

METHODS

We analyzed 162 adult patients with SM (indolent systemic mastocytosis [ISM], n = 65; advanced systemic mastocytosis [advSM], n = 97). First, the cumulative incidence of CMIHR was retrospectively assessed in the patient's history. Second, at our institution, patients underwent 332 contrast media (CM)-enhanced imaging including 80 computed tomography (CT) scans with iodine-based contrast agent and 252 magnetic resonance imaging (MRI) with a gadolinium-based contrast agent, and tolerance was assessed.

RESULTS

Previous CMIHRs to CT (vomiting, n = 1, erythema, n = 1, cardiovascular shock, n = 1), and MRI (dyspnea, n = 1, cardiovascular shock, n = 1) had been reported by 4 out of 162 (2.5%) patients (ISM, n = 3; advSM, n = 1). In contrast, during or after 332 CM-enhanced CT or MRI examinations at our institution, no CMIHRs were reported. Premedication was solely given to 3 patients before CT scans, including 1 with previous CMIHR, who tolerated the imaging well.

CONCLUSION

We conclude that: (1) there is a substantial discrepancy between the perception and prevalence of HRs to CM in SM; (2) reactions are scarce in ISM and even rarer in advSM; and (3) in SM patients without previous history of CM hypersensitivity, prophylactic premedication before CM-enhanced CT or MRI is dispensable.

Anaphylaxis viewed by experts: unmet needs

PURPOSE OF REVIEW

The purpose of the review is to identify unmet needs in the management of anaphylaxis, covering aspects such as epidemiology, diagnosis, treatment and prevention.

RECENT FINDINGS

Redefinition of clinical diagnostic criteria may allow a better identification of anaphylaxis. International diagnostic coding system improvement will be major step for future policies and epidemiological studies. Digital health can aid in managing anaphylaxis.

SUMMARY

Anaphylaxis is a medical emergency; current data show that frequently identification of the reaction, acute and long-term management, are not optimal. Therefore, there is a need to implement strategies to improve the situation. This review has identified unmet needs in anaphylaxis regarding aspects such as epidemiology, severity scoring, definition and diagnostic criteria, anaphylaxis in infants and toddlers, cofactors, biomarkers, long-term management, undertreatment and availability of epinephrine autoinjectors. Strategies focused on education, legislation, digital health and research are proposed.

State-of-the-Art on Biomarkers for Anaphylaxis in Obstetrics

Anaphylaxis is an unpredictable systemic hypersensitivity reaction and constitutes a high risk of maternal and fetal morbidity and mortality when occurring during pregnancy. Currently, the acute management of anaphylaxis is based on clinical parameters. A total serum tryptase is only used to support an accurate diagnosis. There is a need to detect other biomarkers to further assess high-risk patients in obstetrics. Our objective is to present biomarkers in this complex interdisciplinary approach beyond obstetrician and anaesthetic management. Candidate biomarkers derive either from mediators involved in immunopathogenesis or upcoming molecules from systems biology and proteomics. Serum tryptase is determined by singleplex immunoassay method and is important in the evaluation of anaphylactic mast cell degranulation but also in the assessment of other risk factors for anaphylaxis such as systemic mastocytosis. Another category of biomarkers investigates the IgE-mediated sensitization to triggers potentially involved in the etiology of anaphylaxis in pregnant women, using singleplex or multiplex immunoassays. These in vitro tests with natural extracts from foods, venoms, latex or drugs, as well as with molecular allergen components, are useful because in vivo allergy tests cannot be performed on pregnant women in such a major medical emergency due to their additional potential risk of anaphylaxis.

Detection of drug-specific immunoglobulin E (IgE) and acute mediator release for the diagnosis of immediate drug hypersensitivity reactions

The diagnosis of a drug hypersensitivity reaction (DHR) is complex. The first step after taking the clinical history is to look for a sensitization to confirm or exclude the diagnosis and to identify the culprit drug. Skin tests are the primary means of detecting sensitization in DHR, but are associated with a risk for a severe reaction and may be contraindicated. In vitro tests offer the potential to support or confirm a diagnosis of DHR and influence medical decision making. For immediate-type DHR, a few validated assays for measurement of specific IgE (sIgE) are commercially available to a limited number of drugs. In addition, several home-made sIgE radioimmunoassays have been used in other studies. The sensitivity of the sIgE assay is drug-dependant and generally low (0-85%) for betalactams and reported heterogeneous for other drugs ranging from 26% for chlorhexidine and 44% for suxamethonium to 92% for chlorhexidine. However, as all these studies included patients, in whom DHR was confirmed only by skin tests and not by provocation, the results have to be interpreted carefully and may be unreliable. Determination of mediators during an acute phase of a reaction may indirectly support the diagnosis of a DHR by demonstrating mast cell and basophil mediator release. Negative in vitro tests do not exclude a DHR or imputability of a drug, but a positive result may support causality and eliminate the necessity for a drug provocation test. Unfortunately, evidence is limited with a lack of well-controlled studies in larger numbers of well-phenotyped patients, which results in susceptibility for bias and a need for future multicenter studies.

Proteomic and Biological Analysis of an In Vitro Human Endothelial System in Response to Drug Anaphylaxis

Anaphylaxis is a life-threatening systemic hypersensitivity reaction. During anaphylaxis, mediator release by effector cells causes endothelial barrier breakdown, increasing vascular permeability and leakage of fluids, which may lead to tissue edema. Although endothelial cells (ECs) are key players in this context, scant attention has been paid to the molecular analysis of the vascular system, and further analyses of this cell type are necessary, especially in humans. The protein expression pattern of human microvascular ECs was analyzed in response to sera from anaphylactic patients (EC-anaphylaxis) and sera from non-allergic subjects (EC-control) after 2 hours of contact. Firstly, a differential quantitative proteomic analysis of the protein extracts was performed by mass spectrometry using an isobaric labeling method. Second, the coordinated behavior of the identified proteins was analyzed using systems biology analysis (SBA). The proteome of the EC-anaphylaxis system showed 7,707 proteins, of which 1,069 were found to be significantly altered between the EC-control and EC-anaphylaxis groups (p-value < 0.05). Among them, a subproteome of 47 proteins presented a high rate of change (|ΔZq| ≥ 3). This panel offers an endothelial snapshot of the anaphylactic reaction. Those proteins with the highest individual changes in abundance were hemoglobin subunits and structural support proteins. The interacting network analysis of this altered subproteome revealed that the coagulation and complement systems are the main biological processes altered in the EC-anaphylactic system. The comprehensive SBA resulted in 5,512 functional subcategories (biological processes), 57 of which were significantly altered between EC-control and EC-anaphylaxis. The complement system, once again, was observed as the main process altered in the EC system created with serum from anaphylactic patients. Findings of the current study further our understanding of the underlying pathophysiological mechanisms operating in anaphylactic reactions. New target proteins and relevant signaling pathways operating in the in vitro endothelial-serum system have been identified. Interestingly, our results offer a protein overview of the micro-EC-anaphylaxis environment. The relevance of the coagulation, fibrinolytic, contact and complement systems in human anaphylaxis is described. Additionally, the untargeted high-throughput analysis used here is a novel approach that reveals new pathways in the study of the endothelial niche in anaphylaxis.

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.

Mast cell tryptases in allergic inflammation and immediate hypersensitivity

Dysregulated mast cell-mediated inflammation and/or activation have been linked to a number of human diseases, including asthma, anaphylaxis, chronic spontaneous urticaria, and mast cell activation syndromes. As a major mast cell granule protein, tryptase is a biomarker commonly used in clinical practice to diagnose mast cell-associated disorders and -mediated reactions, but its mechanistic roles in disease pathogenesis remains incompletely understood. Here, we summarize recent advances in the understanding of human tryptase genetics and the effects that different genetic composition may have on the quaternary structure of tetrameric mature tryptases. We also discuss how these differences may impact clinical phenotypes including allergic inflammation, immediate hypersensitivity, and others seen in patients with mast cell-associated disorders. With the increased application of next-generation sequencing, we foresee that human genetic approaches will be a major focus of understanding human tryptase functions in various human mast cell disorders and in new therapeutic development.

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.

Intraoperative Hypotension in a Patient with Antithrombin Deficiency, Bilateral Pulmonary Emboli, and Cefazolin Allergy

In medicine, the search for a clear answer can at times be elusive. However, this does not necessarily preclude the administration of intelligent and thoughtful therapeutic treatments. Here, we describe a complicated emergent event of severe hypotension and near-arrest that occurred in the operating room in a young, healthy woman undergoing outpatient thyroid surgery. We detail the situation as it presented in the operating room and the measures taken to rule out potential life-threatening diagnoses and develop a thoughtful treatment plan. We further describe the evidence for and against the two remaining diagnostic possibilities: anaphylaxis versus acute pulmonary embolism.

Directional mast cell degranulation of tumor necrosis factor into blood vessels primes neutrophil extravasation

Tissue resident mast cells (MCs) rapidly initiate neutrophil infiltration upon inflammatory insult, yet the molecular mechanism is still unknown. Here, we demonstrated that MC-derived tumor necrosis factor (TNF) was crucial for neutrophil extravasation to sites of contact hypersensitivity-induced skin inflammation by promoting intraluminal crawling. MC-derived TNF directly primed circulating neutrophils via TNF receptor-1 (TNFR1) while being dispensable for endothelial cell activation. The MC-derived TNF was infused into the bloodstream by directional degranulation of perivascular MCs that were part of the vascular unit with access to the vessel lumen. Consistently, intravenous administration of MC granules boosted neutrophil extravasation. Pronounced and rapid intravascular MC degranulation was also observed upon IgE crosslinking or LPs challenge indicating a universal MC potential. Consequently, the directional MC degranulation of pro-inflammatory mediators into the bloodstream may represent an important target for therapeutic approaches aimed at dampening cytokine storm syndromes or shock symptoms, or intentionally pushing immune defense.

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.

World allergy organization anaphylaxis guidance 2020

Anaphylaxis is the most severe clinical presentation of acute systemic allergic reactions. The occurrence of anaphylaxis has increased in recent years, and subsequently, there is a need to continue disseminating knowledge on the diagnosis and management, so every healthcare professional is prepared to deal with such emergencies. The rationale of this updated position document is the need to keep guidance aligned with the current state of the art of knowledge in anaphylaxis management. The World Allergy Organization (WAO) anaphylaxis guidelines were published in 2011, and the current guidance adopts their major indications, incorporating some novel changes. Intramuscular epinephrine (adrenaline) continues to be the first-line treatment for anaphylaxis. Nevertheless, its use remains suboptimal. After an anaphylaxis occurrence, patients should be referred to a specialist to assess the potential cause and to be educated on prevention of recurrences and self-management. The limited availability of epinephrine auto-injectors remains a major problem in many countries, as well as their affordability for some patients.