Idiopathic Anaphylaxis: a Perplexing Diagnostic Challenge for Allergists

When allergies have no name: is idiopathic anaphylaxis driven by co-factors?

Idiopathic anaphylaxis (IA) is a severe allergic reaction without identifiable external triggers, presenting significant challenges in diagnosis and management. However, growing evidence suggests that many cases classified as idiopathic may actually be driven by cofactors such as exercise, hormonal fluctuations, medications, or hidden allergens. This mini-review explores the evolving understanding of IA, highlighting the role of these cofactors in triggering or amplifying anaphylactic reactions. It emphasizes how advances in diagnostic tools, including component-resolved diagnostics, are helping to identify previously undetected allergens, leading to more accurate diagnoses and reducing the prevalence of true idiopathic cases. As our knowledge of anaphylaxis and its underlying mechanisms deepens, the need for comprehensive evaluations that account for cofactor involvement becomes increasingly clear. Continued research in this area is essential to improve patient outcomes and better manage this complex condition.

Test Panel of Hidden Allergens for "Idiopathic Anaphylaxis" Reveals Wheat Allergy Dependent on Augmentation Factors as Common Final Diagnosis

BACKGROUND

Idiopathic anaphylaxis (IA) is an unresolved concern. Hidden allergens may be relevant in IA and in nonsteroidal anti-inflammatory drug hypersensitivity (NSAID-HS).

OBJECTIVE

To identify hidden elicitors for IA and NSAID-HS by a skin prick test (SPT) (13 allergens) and allergen-specific IgE (sIgE) panel (12 allergens) and to determine the value of each tested allergen.

METHODS

We retrospectively included all patients from 2018 to 2021 referred with a suspicion of IA or NSAID-HS by history in whom SPT and/or sIgE to allergens of the IA panel were performed. Patient characteristics from patients' records included comorbidities, history and symptoms of anaphylaxis, serum baseline tryptase level, total IgE level, SPT, sIgE, challenge results, and final diagnoses.

RESULTS

A total of 134 patients (77 female, mean age 39.7 ± 14.6 years) were included. Median serum baseline tryptase and total IgE levels were 4.23 μg/L and 133.5 kU/L, respectively. Allergologic workup with the IA panel resulted in positive SPT and sIgE in 61 (47%) and 66 (60%) patients, respectively. In those, confirmation or exclusion of allergy, mostly by challenge, led to a definitive diagnosis in 61 of 134 patients (46%). Skin prick test was most frequently positive to gluten (22.4%) and sIgE to ω5-gliadin (21.6%), which correlated with the history (r = 0.310, P < .001; and r = 0.407, P < .001, respectively). In 28 of 134 patients (21%) with initially suspected IA or NSAID-HS, challenges confirmed occult food allergy in which wheat allergy dependent on augmentation factors was the most frequent cause of anaphylaxis (19%).

CONCLUSIONS

Wheat allergy dependent on augmentation factors should be considered in all patients with anaphylaxis of unknown cause or after NSAID intake.

Rare causes of pediatric anaphylaxis due to obscure allergens

This review provides a comprehensive overview of rare causes of pediatric anaphylaxis related to obscure allergens. Anaphylaxis, a severe hypersensitivity reaction, can occur without typical symptoms, posing diagnostic challenges, especially in children. Idiopathic anaphylaxis, where no trigger is identified despite thorough evaluation, is notably challenging in this population. This review synthesizes current literature, highlighting obscure triggers such as food additives, spices like fenugreek, and cross-reactive allergens, including lupine and gelatin. These allergens are often overlooked and can lead to misdiagnosis of idiopathic cases. Understanding these uncommon triggers is crucial for clinicians to ensure accurate diagnosis and effective management of pediatric anaphylaxis, emphasizing the need for heightened clinical awareness and further research. This review raises awareness among health care providers about these lesser-known causes, aiming to improve outcomes and quality of life for pediatric patients at risk of anaphylactic reactions.

Pediatric idiopathic anaphylaxis: practical management from infants to adolescents

Idiopathic anaphylaxis (IA) remains a frustrating challenge for both patients and physicians. The aim of this paper is to focus on IA in pediatric ages and suggest possible diagnostic algorithms according to specific age ranges (infants, children, and adolescents). In fact, in a variable percentage of patients, despite extensive diagnostic tests, the cause of anaphylactic episodes cannot be identified. Moreover, the lack of a unanimous IA definition requires a careful and detailed diagnostic workup. Prompt recognition of signs and symptoms, especially in younger children, and an accurate clinical history often allow a choice of the most appropriate diagnostic tests and a correct differential diagnosis.

Alpha-Gal Syndrome: An Underrated Serious Disease and a Potential Future Challenge

Over the past decades, red meat allergy, also known as mammalian meat allergy, which manifests differently from classic food allergies, has been reported in different countries and regions, including China. The allergen of this disease is not a protein but an oligosaccharide: galactose-α-1,3-galactose, i.e., alpha-gal or α-gal. Therefore, this clinical syndrome is also called α-gal syndrome (AGS). It clinically manifests as delayed anaphylaxis, i.e., patients generally develop allergic symptoms 2-6 h after ingesting red meat. This clinical manifestation is believed to be related to sensitization to α-gal after tick bites. Sensitized individuals may also develop anaphylaxis after ingesting food and medicine or being exposed to medical equipment containing α-gal, such as cetuximab and gelatin. Here, the literature on AGS is reviewed for a better understanding of its pathogenesis, clinical diagnosis, and treatment.

Mast cell activation syndrome: An up-to-date review of literature

Mast cells are a subtype of white blood cells and are involved in the immune system. These cells contain many chemical substances called mediators, which are involved in the allergic response. The fact that mast cells play a role in many events that require urgent intervention, especially anaphylaxis, has led to a more detailed study of these cells. The diseases also caused by dysfunctions of mast cells have been examined in many circumstances. For instance, mast cell activation syndrome is known as an augmented number of cells due to decreased cell death, resulting in clinical symptoms affecting many systems. The main common symptoms include flushing, hypotension, urticaria, angioedema, headache, vomiting and diarrhea. Although the underlying mechanism is not yet clearly known, we aim to review the literature in a broad perspective and bring together the existing knowledge in the light of the literature due to the diversity of its involvement in the body and the fact that it is a little known syndrome.

Using differential mobility spectrometry to improve the specificity of targeted measurements of 2,3-dinor 11β-Prostaglandin F2α

INTRODUCTION

2,3-dinor 11β-Prostaglandin F2α (BPG) is an arachidonic acid derivative and the most abundant metabolic byproduct of prostaglandin D2, which is released during mast cell activation. Therefore, measurements of BPG in urine using liquid chromatography-tandem mass spectrometry (LC-MS/MS) provide a noninvasive method for evaluation and management of mast cell disorders. Measurements obtained by LC-MS/MS exhibit a high prevalence of chromatographic interferences resulting in challenges with optimal determination of BGP. In this investigation, differential mobility spectrometry (DMS) is utilized to overcome the limitations of current testing.

METHODS

Urine samples were extracted using an automated solid-phase extraction method. Samples were then analyzed with and without DMS devices installed on two commercially available mass spectrometry platforms to assess the benefits of DMS. Following promising results from a preliminary analytical evaluation, LC-DMS-MS/MS measurements of BPG in urine were fully validated to assess the analytical implications of using this technology.

RESULTS AND DISCUSSION

The addition of DMS devices to the LC-MS/MS systems evaluated in this investigation significantly reduced interferences observed in the chromatograms. Concomitantly, DMS reduced the number of discordant quantifier/qualifier fragment ion results that significantly exceeded the ± 20 % limits, suggesting greater analytical specificity. The validation studies yielded low interday imprecision, with %CVs less than 6.5 % across 20 replicate measurements. Validation studies assessing other aspects of analytical performance also met acceptance criteria.

CONCLUSIONS

Incorporating DMS devices greatly improved the specificity of BPG measurements by LC-MS/MS, as evidenced by the comparison of chromatograms and fragment ion results. Validation studies showed exceptional performance for established analytical metrics, indicating that this technology can be used to minimize the impact of interferences without adversely impacting other aspects of analytical or clinical performance.

Prevention of Anaphylaxis Episodes in Idiopathic Anaphylaxis by Omalizumab

INTRODUCTION

In 15-35 percent of patients with anaphylaxis, the triggering allergen cannot be found; therefore, a diagnosis of idiopathic anaphylaxis (IA) is made. We report on the outcomes in patients with IA treated with omalizumab.

METHODS

We included consequent omalizumab-treated IA adult patients treated with omalizumab 300 mg every 4 weeks.

RESULTS

Out of 7 patients, 6 were female, median age 40 years with the frequency of anaphylaxis episodes from 3 in 2 years to 5 in 4 months. Baseline tryptase ranged from 1.71 to 12.0 μg/L. An increase in tryptase during anaphylaxis was documented in 6 patients. Activating KIT p.D816V variant was detected in 2 patients. One patient also had hereditary alpha-tryptasemia (HαT). The duration of omalizumab treatment was 0.5-7.5 years. None of the patients have experienced an anaphylactic reaction since the start of treatment. Mild systemic reactions were reported in 6 patients (86%). The presence of underlying cMCD had no impact on the treatment outcome.

CONCLUSION

All patients in our study had complete responses to omalizumab. The presence of KIT p.D816V and HαT did not influence the response to omalizumab treatment.

Low Prevalence of Idiopathic Mast Cell Activation Syndrome Among 703 Patients With Suspected Mast Cell Disorders

BACKGROUND

Idiopathic mast cell activation syndrome (iMCAS) is characterized by severe, episodic systemic mast cell (MC) activation and mediator-related symptoms, an event-related increase in serum tryptase levels, and response to MC-targeted therapies in the absence of underlying IgE-mediated allergy or clonal MC disorder. Studies indicating its prevalence using evidence-based diagnostic criteria are lacking.

OBJECTIVE

To assess the prevalence and clinical and laboratory features of patients with iMCAS.

METHODS

We conducted a retrospective evaluation of data from 703 consecutive patients (aged ≥18 years) referred to our center based on suspicion of having MC disorders. Patients underwent a thorough clinical workup including patient history, allergy tests, KIT D816V mutation analysis, and/or bone marrow investigation. Disease activity was prospectively assessed during follow-up visits.

RESULTS

We identified 31 patients with confirmed iMCAS. Furthermore, hereditary α-tryptasemia was detected in three patients with baseline tryptase levels greater than 8 ng/mL. The most common clinical presentation during MCAS episodes was mucocutaneous symptoms in patients with iMCAS, especially urticaria or angioedema. However, these symptoms were less prevalent in patients with clonal MCAS (P = .015). The duration of diagnostic delay was significantly longer in patients with iMCAS compared to those with clonal MCAS (P = .02).

CONCLUSIONS

The overall prevalence of iMCAS was 4.4% in the entire cohort, which indicates that iMCAS is an uncommon condition. To accurately diagnose iMCAS, it is crucial to evaluate suspected patients using the three diagnostic MCAS criteria. This involves performing a comprehensive allergy work-up including laboratory tests and ultrasensitive mutation analysis of KIT D816V. Subsequently, recommended diagnostic algorithms should be applied.

Using the Right Criteria for MCAS

PURPOSE OF REVIEW

The current article aims to provide a comprehensive update on diagnostic criteria for mast cell activation syndrome (MCAS), addressing challenges in diagnosing and classifying MCAS and its variants.

RECENT FINDINGS

In recent years, there has been a significant increase in our knowledge regarding the underlying mechanisms responsible for the activation of mast cells (MCs) in various pathological conditions. Furthermore, a set of criteria and a classification for MCASs have been established. MCAS is characterized by the presence of typical clinical symptoms, a substantial elevation in serum tryptase levels during an attack compared to the patient's baseline tryptase levels, and a response to MC mediator-targeting therapy. In this report, a thorough examination was conducted on the contemporary literature relating to MCAS, with a focus on comparing the specificity, sensitivity, and robustness of MCAS-related parameters within proposals for diagnosing and classifying MCAS and its variants. Moreover, the significance of employing specific consensus criteria in the assessment and categorization of MCAS in individual patients was underscored, due to the escalating occurrence of patients receiving a misdiagnosis of MCAS based on nonspecific criteria.

Predictors of Clonality and Underlying Mastocytosis in Mast Cell Activation Syndromes

PURPOSE OF REVIEW

Mast cell (MC) activation can present with a wide range of symptoms. The mechanisms that cause such activation are varied. One of them is the presence of clonal MCs which is defined, within other possible changes, by the presence of a somatic, activating mutation in the KIT gene. The clinical course and prognosis of patients with this underlying disease may be different from other causes of MC activation (MCA). For this reason, it is important to early diagnose, or at least suspect, which patients with MCA are due to clonal MCs.

RECENT FINDINGS

The diagnosis of clonality must be made in a comprehensive manner. However, this paper reviews chronologically each of the stages from the patient's first visit to the doctor's office which can be indicative of clonality: clinical presentation of MCA, physical examination, analytical determinations of tryptase, and/or KIT mutational analysis and bone involvement, among others. The different clonality predictive scores proposed are also reviewed and compared. Although the gold standard for the diagnosis of certainty of MC clonality is the performance of a bone marrow (BM) biopsy, there are clinical symptoms, signs, and biological parameters suggestive of clonality, as well as predictive scores, which can guide (or rule out) an early diagnosis and avoid unnecessary BM biopsies.

Management of Mediator Symptoms, Allergy, and Anaphylaxis in Mastocytosis

Mastocytosis is characterized by expansion and activation of clonally aberrant mast cells (MCs) in one or more organ systems. Inappropriate MC activation is a key finding in both allergy and mastocytosis; therefore, symptoms in both conditions show some degree of overlap. When mediator release is excessive and involves multiple systems, anaphylaxis may occur. In mastocytosis, the prevalence of atopy is similar to those of the general population, whereas the incidence of anaphylaxis is significantly higher. The purpose of this review is to discuss features of allergy and anaphylaxis as well as the principles of managing MC mediator release symptoms in mastocytosis.

A Puzzling Mast Cell Trilogy: Anaphylaxis, MCAS, and Mastocytosis

Our knowledge of biology and mast cell (MC) function, as well as disorders associated with the pathologic activation of MCs, has evolved over the last few decades. Anaphylaxis, mast cell activation syndrome (MCAS), and mastocytosis are interrelated yet distinct conditions within the spectrum of mast cell activation disorders. Nevertheless, all three conditions can co-exist in one and the same patient, as pathologic MC activation is the key finding in all three. When mediator release is excessive and involves multiple systems, anaphylaxis and MCAS may occur. Furthermore, mastocytosis is a clonal disorder of MCs and often presents with anaphylaxis and MCAS. Nevertheless, in some cases, even the proliferative and accumulative features of MCs in mastocytosis can account for symptoms and disease progression. In each case, diagnosis can be only made when the diagnostic consensus criteria are fulfilled. The current article aims to provide a concise clinical update and pinpoint the main difficulties in diagnosing these puzzling disorders of MCs in medical practice.

Immunoreactive proteins of Capsicum-based spices as a threat to human health: mass spectrometry analysis and in silico mapping

Dietary patterns are changing severely, especially the consumption of highly processed foods with lots of spices is increasing, carrying an increased risk of immediate hypersensitivity (type I), in sensitised individuals, due to the possible presence of allergens, especially the hidden ones. Paprika is a fruit of the Capsicum genus, which belongs to the Solanaceae family and is commonly consumed fresh or as a spice. Despite recorded cases of anaphylaxis, its allergenicity has yet to be clearly investigated. In this study, we research to identify proteins that could trigger a severe allergic reaction in patients with an equivocal clinical picture. Two types of protein extracts extracted from 3 different paprika spices were immunoblotted with sera from patients with severe allergic symptoms, presumably to paprika. Proteins from the IgE reactive bands obtained were subjected to LC-MS/MS identification and then in silico analysis to assess their possible sensitising capacity and proinflammatory potential using online tools. The spices were shown to contain a number of incompletely investigated highly immunoreactive allergenic proteins, including proteins of foreign origin (contaminants), the presence of which can stimulate inflammatory mechanisms and cross-reactivity with other food allergens, which can threaten life and health and should be investigated in detail.

Disease Spectrum of Anaphylaxis Disorders

Anaphylaxis results from massive mast cell activation. Mechanisms of mast cell activation may involve IgE- and non-IgE-mediated triggers, clonal mast cell disease, or be idiopathic and may be modified by several factors including but not restricted to hormonal status, stress, heritable factors, mast cell burden, and simultaneous exposure to more than 1 factor. Patients with recurrent anaphylaxis with a nonidentifiable trigger present a particular challenge in diagnosis and management. Presence of clonal disease may be suggested by hypotensive episodes with urticaria and angioedema, and high baseline tryptase levels. A number of scoring systems have been developed to identify patients who are at high risk to have underlying mastocytosis. This review provides an overview of anaphylaxis disorders and our current understanding of their mechanisms of action, evaluation, and management.

Mast Cell Activation Syndromes: Comparison Between Two Scoring Models to Predict for Mast Cell Clonality

BACKGROUND

The Red Española de Mastocitosis (Spanish Network on Mastocytosis) score (REMAs) and the National Institutes of Health idiopathic clonal anaphylaxis score (NICAS) were developed for more efficient screening of mast cell (MC) clonality in MC activation syndromes. In a limited idiopathic anaphylaxis case series, the NICAS showed higher accuracy compared with the REMAs.

OBJECTIVE

To compare the performance of the REMAs against the NICAS in the diagnosis of MC clonality.

METHODS

We compared the diagnostic value of the REMAs against the NICAS in 182 patients (63% men, median age 56 years) who presented with anaphylaxis triggered by Hymenoptera venom allergy (45%), drugs (15%), food (11%), idiopathic anaphylaxis (20%), and mixed causes (10%). KIT mutation was assessed in parallel in whole blood and bone marrow (BM) and, when negative, in highly purified BM MC. TPSAB1 was genotyped in a subset of 71 patients.

RESULTS

We found higher accuracy and rates of correctly classified patients for the REMAs (82% and 84%) compared with the NICAS (75% and 75%; P = .02 and P = .03, respectively), particularly among men (P = .05), patients with systemic mastocytosis (P = .05), those presenting anaphylaxis owing to any cause featuring urticaria (P = .04), cardiovascular symptoms (P = .02), and/or presyncope (P = .02) and those with a blood-negative/BM-positive KIT mutational profile (P = .002), but not hereditary α-tryptasemia-associated genotypes. Combined assessment of the REMAs and KIT^D816V in blood yielded an overall improved classification efficiency of 86% versus 84% for REMAs.

CONCLUSIONS

The combined use of the REMAs and blood detection of KIT^D816V is recommended, but more sensitive blood-based molecular assays to detect KIT^D816V are needed.

Mast cells in food allergy: Inducing immediate reactions and shaping long-term immunity

Mast cells are distributed throughout the gastrointestinal tract and function as the main effector cells of IgE-mediated allergic reactions to foods. Allergen-induced cross-linking of IgE antibodies bound to high-affinity IgE receptors, FcεRI, on the surface of mast cells triggers their activation, resulting in the release of mediators of immediate hypersensitivity. These mediators rapidly induce both local gastrointestinal and systemic physiological responses including anaphylaxis. Emerging evidence has revealed that, in addition to inciting immediate reactions, mast cells are key regulators of adaptive immunity to foods. In the gastrointestinal mucosa they provide the priming cytokines that initiate and, over time, consolidate adaptive T_H2 responses to ingested allergens as well as TNF and chemokines that orchestrate the recruitment of tissue-infiltrating leukocytes that drive type 2 tissue inflammation. Patients with atopic dermatitis have increased intestinal mast cell numbers and are at a greater risk for food allergy. Recent studies have uncovered a skin-gut axis in which epicutaneous allergen exposure drives intestinal mast cell expansion. The activating effects of IgE antibodies in mast cells are countered by food-specific IgG antibodies that signal via the inhibitory IgG receptor, FcγR2b, suppressing both immediate allergic reactions to foods and the type 2 immune adjuvant activity of mast cells.

Boxed Warnings and Off-Label Use of Allergy Medications: Risks, Benefits, and Shared Decision Making

The Food and Drug Administration is tasked with evaluating the efficacy and safety of a drug. Despite having a regimented appraisal process in place, safety evidence can emerge during clinical trials as well as from observations and studies conducted after the drug has been on the market, which might require a boxed warning. The boxed warning is the most severe warning that the Food and Drug Administration can give to an approved drug. It is commonly referred to as a Black Box Warning because it is outlined in the package insert by a thick black box to garner the attention of prescribers and patients. There are currently more than 400 medications that have boxed warnings, and the information addressing major risks associated with a particular drug may, appropriately or inappropriately, influence patient and clinician decision making. Health care professionals must use the best evidence and clinical judgment in determining whether to prescribe medications with these warnings. Use of an approved drug at dosages or for indications other than what it was originally licensed for is referred to as "off-label" and is legal, commonplace, and may be evidence-based. All drugs may expose patients to possible harm, so prescribers have an obligation to discuss the best available evidence regarding benefits and harms so that patients can participate in shared decision making.

The Meat of the Matter: Understanding and Managing Alpha-Gal Syndrome

Alpha-gal syndrome is an unconventional food allergy, characterized by IgE-mediated hypersensitivity responses to the glycan galactose-alpha-1,3-galactose (alpha-gal) and not to a food-protein. In this review, we discuss how alpha-gal syndrome reframes our current conception of the mechanisms of pathogenesis of food allergy. The development of alpha-gal IgE is associated with tick bites though the possibility of other parasites promoting sensitization to alpha-gal remains. We review the immune cell populations involved in the sensitization and effector phases of alpha-gal syndrome and describe the current understanding of why allergic responses to ingested alpha-gal can be delayed by several hours. We review the foundation of management in alpha-gal syndrome, namely avoidance, but also discuss the use of antihistamines, mast cell stabilizers, and the emerging role of complementary and alternative therapies, biological products, and oral immunotherapy in the management of this condition. Alpha-gal syndrome influences the safety and tolerability of medications and medical devices containing or derived from mammalian products and impacts quality of life well beyond food choices.

Pediatric Anaphylaxis: A 20-Year Retrospective Analysis

BACKGROUND

Anaphylaxis is a steadily increasing global problem defined as an acute hypersensitivity multisystem reaction that is potentially fatal. In the pediatric age, the leading cause is food. In other allergic diseases, intrinsic heterogeneity has been reported in the clinical presentation, severity, and triggers of anaphylaxis. This study analyzes the features and management approach of the anaphylactic reactions in children evaluated at the pediatric clinic in Pavia.

MATERIALS AND METHODS

A retrospective study was conducted on patients with anaphylaxis between 2001 and 2021.

RESULTS

A total of 148 patients with a median age of 5 years were enrolled, and 80% of the patients had other atopic comorbidities that were correlated with the severity of anaphylaxis. The main trigger of anaphylaxis was food. Most reactions involved mucocutaneous, respiratory, and gastrointestinal systems, and occurred at home. Adrenaline was administered only in a minority of cases.

CONCLUSIONS

Considering that anaphylaxis is a potentially life-threatening condition requiring prompt management, the use of adrenaline should be implemented. Our data also suggest the importance of educating and spreading awareness of anaphylactic management within the medical community.

Acute Urticaria and Anaphylaxis: Differences and Similarities in Clinical Management

Acute urticaria is a common condition that presents with wheals and/or angioedema. However, these symptoms are also frequent in anaphylaxis, a life-threatening reaction that should be immediately diagnosed and treated. In both, mast cells play a central role in the physiopathology. Causes and triggers of acute urticaria and anaphylaxis are similar in general, but some peculiarities can be observed. The diagnostic approach may differ, accordingly to the condition, suspicious causes, age groups and regions. Adrenaline is the first-line treatment for anaphylaxis, but not for acute urticaria, where H1-antihistamines are the first choice. In this paper, we review the main aspects, similarities and differences regarding definitions, mechanisms, causes, diagnosis and treatment of acute urticaria and anaphylaxis.

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.

Mastocytosis and Mast Cell Activation Disorders: Clearing the Air

Mast cells are derived from hematopoietic stem cell precursors and are essential to the genesis and manifestations of the allergic response. Activation of these cells by allergens leads to degranulation and elaboration of inflammatory mediators, responsible for regulating the acute dramatic inflammatory response seen. Mast cells have also been incriminated in such diverse disorders as malignancy, arthritis, coronary artery disease, and osteoporosis. There has been a recent explosion in our understanding of the mast cell and the associated clinical conditions that affect this cell type. Some mast cell disorders are associated with specific genetic mutations (such as the D816V gain-of-function mutation) with resultant clonal disease. Such disorders include cutaneous mastocytosis, systemic mastocytosis (SM), its variants (indolent/ISM, smoldering/SSM, aggressive systemic mastocytosis/ASM) and clonal (or monoclonal) mast cell activation disorders or syndromes (CMCAS/MMAS). Besides clonal mast cell activations disorders/CMCAS (also referred to as monoclonal mast cell activation syndromes/MMAS), mast cell activation can also occur secondary to allergic, inflammatory, or paraneoplastic disease. Some disorders are idiopathic as their molecular pathogenesis and evolution are unclear. A genetic disorder, referred to as hereditary alpha-tryptasemia (HαT) has also been described recently. This condition has been shown to be associated with increased severity of allergic and anaphylactic reactions and may interact variably with primary and secondary mast cell disease, resulting in complex combined disorders. The role of this review is to clarify the classification of mast cell disorders, point to molecular aspects of mast cell signaling, elucidate underlying genetic defects, and provide approaches to targeted therapies that may benefit such patients.

Mast cell activation syndrome: is anaphylaxis part of the phenotype? A systematic review

PURPOSE OF REVIEW

Mast cell activation syndrome (MCAS) and anaphylaxis are the result of a spontaneous or triggered pathological degranulation of mast cells (MCs) and might have as substrate normal or pathological MCs (increased burden, aberrant MCs or both).

RECENT FINDINGS

This review summarizes the most recent evidence on immunoglobulin E (IgE)-mediated and non IgE-mediated mechanisms underlying MC activation and degranulation and highlights the importance of standardized diagnostic criteria for MCAS. Application of these criteria implies that in most cases the clinical presentation of MCAS meets the diagnostic criteria for anaphylaxis.

SUMMARY

Integrating clinical parameters and diagnostic test recognition and underlying clonal MC disease are of utmost importance for a patient-tailored approach. Hereditary alpha-tryptasemia can be encountered in context of anaphylaxis, MCAS and primary MC disorders.