Predictive values of alpha-gal IgE levels and alpha-gal IgE: Total IgE ratio and oral food challenge-proven meat allergy in a population with a high prevalence of reported red meat allergy

Alpha-Gal Syndrome and Cardiac Surgery

Galactose-alpha-1,3-galactose (alpha-gal) is a carbohydrate expressed by all mammals except for humans and certain old-world primates. It can be found in a plethora of products derived from mammals, including milk, organs, skeletal muscle and gelatin, in addition to products prepared with mammalian cells or constituents. In the late 2000s, an association between tick bites and the development of immunoglobulin E antibodies to the alpha-gal carbohydrate was discovered. The term "alpha-gal syndrome" (AGS) was then coined to describe allergic reactions to mammalian meat or other alpha-gal-containing products derived from mammals. Symptoms are often delayed several hours from consumption and can be urticarial and/or gastrointestinal. Medications and bioprosthetic inserts derived from mammals were also noted to cause allergic reactions in affected patients. Cardiac surgery, in particular, is considered high risk, given that unfractionated heparin has a bovine or porcine origin and is administered in large doses for cardiopulmonary bypass. Bioprosthetic valves have similar origins and risks. Awareness of AGS in cardiac surgery patients can lead to decreased risk preoperatively and inform management perioperatively and postoperatively. In this narrative review, we have reviewed the published literature relevant to AGS in patients undergoing cardiac surgery and shared our treatment approach.

Increasing prevalence of galactose-α-1,3-galactose sensitization in the Danish general adult population

BACKGROUND

Alpha-gal syndrome is a novel food allergy to the oligosaccharide galactose-α-1,3-galactose (alpha-gal) present in mammalian meat. Tick bites are considered an important route of sensitization to alpha-gal. Data on alpha-gal sensitization in the general population is scant. We utilized a unique data source of repeated population-based health examination studies to assess prevalence, time trends, risk factors, and characteristics of alpha-gal sensitization.

METHODS

Alpha-gal sensitization was assessed in >11.000 adults from four health examination studies of randomly invited residents in the Copenhagen region conducted in 1990-1991, 2011-2012, 2012-2015, and 2016-2017. Alpha-gal sensitization was defined as serum specific IgE (sIgE) to alpha-gal ≥0.1 kUA/L; ≥0.35 kUA/L; ≥0.7 kUA/L; ≥3.5 kUA/L. The population was characterized according to genetically determined ABO blood group, aeroallergen sensitization, and pets at home.

RESULTS

The prevalence of sIgE to alpha-gal ≥0.1 kUA/L was 1.3% in 1990-1991, 3.7% in 2012-2015 and 3.2% in 2016-2017. Of those sensitized to alpha-gal >97% reported to consume red meat at least once a week, even for sIgE to alpha-gal ≥3.5 kUA/L. Male sex, older age, aeroallergen sensitization, cat at home, and blood group A were associated with increased odds of alpha-gal sensitization. The known protective effect of blood group B was confirmed.

CONCLUSION

In this general adult population, the prevalence of alpha-gal sensitization had doubled from 1990-1991 to 2016-2017. This could potentially be due to increased tick exposure and an increased atopic predisposition.

Mammalian Meat Allergy and IgE to Alpha-Gal in Central Virginia: Findings From a COVID-19 Vaccine and Patient Cohort

BACKGROUND

IgE to galactose-alpha-1,3-galactose (alpha-gal) is linked to tick bites and an important cause of anaphylaxis and urticarial reactions to mammalian meat. The alpha-gal syndrome (AGS) is recognized as being common in the southeastern United States. However, prevalence studies are lacking and open questions remain about risk factors and clinical presentation of alpha-gal sensitization.

OBJECTIVE

Here we characterized the prevalence as well as the presentation and risk factors of AGS and alpha-gal IgE sensitization in adults in central Virginia recruited without regard to the history of allergic disease.

METHODS

Adults in central Virginia, primarily University of Virginia Health employees, were recruited as part of a COVID-19 vaccine study. Subjects provided at least one blood sample and answered questionnaires about medical and dietary history. We used ImmunoCAP for IgE assays and assessed the ABO blood group by reverse typing using stored serum. We also investigated biobanked serum from COVID-19 patients.

RESULTS

Median age of the 267 enrollees was 42 years, 76% were female, and 43 (16%) were sensitized to alpha-gal (cutoff of 0.1 IU/mL), of which mammalian meat allergy was reported by seven (2.6%). Sensitized subjects (1) were older, (2) had higher total IgE levels but a similar frequency of IgE to common respiratory allergens, and (3) were more likely to report tick bites than were nonsensitized subjects. Among those who were sensitized, alpha-gal IgE levels were higher among meat-allergic than nonallergic subjects (geometric mean, 9.0 vs 0.5 IU/mL; P < .001). Mammalian meat and dairy consumption was common in individuals with low-level sensitization.

CONCLUSION

In central Virginia, AGS is a dominant cause of adult food allergy with a prevalence approaching or exceeding 2%.

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.

Clinical Presentation and Outcomes of Alpha-Gal Syndrome

BACKGROUND AND AIMS

Alpha-gal syndrome (AGS) is an IgE-mediated allergic reaction to galactose-α-1,3-galactose, primarily linked with Lone Star tick bites in the United States. It presents with symptoms ranging from urticaria and gastrointestinal (GI) manifestations to delayed anaphylaxis following red meat consumption. We aimed to study AGS patients' clinical manifestations, diagnosis, and outcomes.

METHODS

A retrospective chart review of patients who underwent serological testing for suspected AGS between 2014 and 2023 at Mayo Clinic was performed. Patients with positive serology were age and sex matched with those who tested negative. Clinical characteristics of seropositive cohort with and without GI symptoms were compared, and outcomes assessed.

RESULTS

Of 1260 patients who underwent testing, 124 tested positive for AGS. They were matched with 380 seronegative control subjects. AGS patients reported a higher frequency of tick bites (odds ratio [OR], 26.0; 95% confidence interval [CI], 9.8-68.3), reported a higher prevalence of urticaria (56% vs 37%; P = .0008), and were less likely to have asthma (OR, 0.4; 95% CI, 0.3-0.7). They had a lower prevalence of heartburn (6% vs 12%; P = .03) and bloating (6% vs 13%; P = .03). A total of 47% had GI symptoms, and a higher proportion were female than those without GI symptoms (69% vs 35%; P = .002). During a mean follow-up of 27 months, 22 of 40 patients reported symptom resolution after avoiding red meat, and 7 were able to transition to regular diet.

CONCLUSIONS

A diagnosis of AGS should be strongly considered in patients with a history of tick bites and clinical presentation of allergic or GI manifestations. Dietary intervention is effective in most but not all patients.

Allergenic potency of various foods of mammalian origin in patients with α-Gal syndrome

BACKGROUND

The α-Gal syndrome (AGS) is an emerging allergy to mammalian food caused by IgE-mediated reactions to the carbohydrate galactose-α-1,3-galactose (α-Gal). Mammalian food sources contain α-Gal, but the amount differs. The objective of this study was to investigate the allergenic potency of various foods of mammalian origin among AGS patients.

METHODS

Twenty-six AGS patients were included. Food extracts from innards, lean meats, processed meat products, milk, and whey were analyzed. Immunoblot, ELISA, immunofluorescence, and basophil activation test were used to determine the α-Gal content, characterize IgE binding, and assess foods' allergenicity.

RESULTS

The determined amount of α-Gal, IgE reactivity to food extracts, and food extract potencies to activate patients' basophils correlated well with each other. Pork and beef kidney showed the highest allergenicity. Beef liver and bacon showed allergenicity comparable to that of lean meats. Game meat seemed to have a higher allergenic potency than meats from farm-raised animals. The processed meat products liver pâté and black pudding, despite lower α-Gal content, demonstrated moderate allergenicity. Milk showed the lowest allergenicity. IgE reactivity to food extracts was highly similar for all patients and strongly dominated by the α-Gal epitope.

CONCLUSIONS

The allergenic potency of mammalian meat depends on the origin of the meat, the different cuts, and type of processing, with innards posing the greatest risk to AGS patients. Even processed mammalian meat constitutes a risk. Dairy products show the lowest risk. This study highlights the importance of analyzing even more foods to improve the management of AGS.

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.

Tick bites, IgE to galactose-alpha-1,3-galactose and urticarial or anaphylactic reactions to mammalian meat: The alpha-gal syndrome

The recent recognition of a syndrome of tick-acquired mammalian meat allergy has transformed the previously held view that mammalian meat is an uncommon allergen. The syndrome, mediated by IgE antibodies against the oligosaccharide galactose-alpha-1,3-galactose (alpha-gal), can also involve reactions to visceral organs, dairy, gelatin and other products, including medications sourced from non-primate mammals. Thus, fittingly, this allergic disorder is now called the alpha-gal syndrome (AGS). The syndrome is strikingly regional, reflecting the important role of tick bites in sensitization, and is more common in demographic groups at risk of tick exposure. Reactions in AGS are delayed, often by 2-6 h after ingestion of mammalian meat. In addition to classic allergic symptomatology such as urticaria and anaphylaxis, AGS is increasingly recognized as a cause of isolated gastrointestinal morbidity and alpha-gal sensitization has also been linked with cardiovascular disease. The unusual link with tick bites may be explained by the fact that allergic cells and mediators are mobilized to the site of tick bites and play a role in resistance against ticks and tick-borne infections. IgE directed to alpha-gal is likely an incidental consequence of what is otherwise an adaptive immune strategy for host defense against endo- and ectoparasites, including ticks.

Epidemiology and the Growing Epidemic of Food Allergy in Children and Adults Across the Globe

PURPOSE OF REVIEW

Food allergies are immune-mediated, complex disorders, which are the source of increasing health concern worldwide. The goal of this review is to present an updated summary of the food allergy (FA) burden among children and adults across different populations, focusing on research from the past 5 years.

RECENT FINDINGS

FAs impact a growing number of global residents-particularly those residing in higher-income, industrialized regions. Moreover, growing epidemiologic evidence suggests that the population health burden of non-IgE-mediated FAs, such as food protein-induced enterocolitis syndrome, may also be higher than previously reported. FA is a complex trait that impacts infants, children, as well as adults across the globe. The population health burden of both IgE- and non-IgE-mediated FAs is likely to grow in the absence of rapid advances and widespread implementation of effective FA prevention and treatment interventions. Systematic epidemiological research initiatives are needed, both nationally and globally, to better understand and reduce the burden of these allergic diseases.

Management of Food Allergies and Food-Related Anaphylaxis

Importance

An estimated 7.6% of children and 10.8% of adults have IgE-mediated food-protein allergies in the US. IgE-mediated food allergies may cause anaphylaxis and death. A delayed, IgE-mediated allergic response to the food-carbohydrate galactose-α-1,3-galactose (alpha-gal) in mammalian meat affects an estimated 96 000 to 450 000 individuals in the US and is currently a leading cause of food-related anaphylaxis in adults.

Observations

In the US, 9 foods account for more than 90% of IgE-mediated food allergies-crustacean shellfish, dairy, peanut, tree nuts, fin fish, egg, wheat, soy, and sesame. Peanut is the leading food-related cause of fatal and near-fatal anaphylaxis in the US, followed by tree nuts and shellfish. The fatality rate from anaphylaxis due to food in the US is estimated to be 0.04 per million per year. Alpha-gal syndrome, which is associated with tick bites, is a rising cause of IgE-mediated food anaphylaxis. The seroprevalence of sensitization to alpha-gal ranges from 20% to 31% in the southeastern US. Self-injectable epinephrine is the first-line treatment for food-related anaphylaxis. The cornerstone of IgE-food allergy management is avoidance of the culprit food allergen. There are emerging immunotherapies to desensitize to one or more foods, with one current US Food and Drug Administration-approved oral immunotherapy product for treatment of peanut allergy.

Conclusions and Relevance

IgE-mediated food allergies, including delayed IgE-mediated allergic responses to red meat in alpha-gal syndrome, are common in the US, and may cause anaphylaxis and rarely, death. IgE-mediated anaphylaxis to food requires prompt treatment with epinephrine injection. Both food-protein allergy and alpha-gal syndrome management require avoiding allergenic foods, whereas alpha-gal syndrome also requires avoiding tick bites.

Systematic review and meta-analyses on the accuracy of diagnostic tests for IgE-mediated food allergy

The European Academy of Allergy and Clinical Immunology (EAACI) is updating the Guidelines on Food Allergy Diagnosis. We aimed to undertake a systematic review of the literature with meta-analyses to assess the accuracy of diagnostic tests for IgE-mediated food allergy. We searched three databases (Cochrane CENTRAL (Trials), MEDLINE (OVID) and Embase (OVID)) for diagnostic test accuracy studies published between 1 October 2012 and 30 June 2021 according to a previously published protocol (CRD42021259186). We independently screened abstracts, extracted data from full texts and assessed risk of bias with QUADRAS 2 tool in duplicate. Meta-analyses were undertaken for food-test combinations for which three or more studies were available. A total of 149 studies comprising 24,489 patients met the inclusion criteria and they were generally heterogeneous. 60.4% of studies were in children ≤12 years of age, 54.3% were undertaken in Europe, ≥95% were conducted in a specialized paediatric or allergy clinical setting and all included oral food challenge in at least a percentage of enrolled patients, in 21.5% double-blind placebo-controlled food challenges. Skin prick test (SPT) with fresh cow's milk and raw egg had high sensitivity (90% and 94%) for milk and cooked egg allergies. Specific IgE (sIgE) to individual components had high specificity: Ara h 2-sIgE had 92%, Cor a 14-sIgE 95%, Ana o 3-sIgE 94%, casein-sIgE 93%, ovomucoid-sIgE 92/91% for the diagnosis of peanut, hazelnut, cashew, cow's milk and raw/cooked egg allergies, respectively. The basophil activation test (BAT) was highly specific for the diagnosis of peanut (90%) and sesame (93%) allergies. In conclusion, SPT and specific IgE to extracts had high sensitivity whereas specific IgE to components and BAT had high specificity to support the diagnosis of individual food allergies.

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.

The α-Gal epitope - the cause of a global allergic disease

The galactose-α-1,3-galactose (α-Gal) epitope is the cause of a global allergic disease, the α-Gal syndrome (AGS). It is a severe form of allergy to food and products of mammalian origin where IgE against the mammalian carbohydrate, α-Gal, is the cause of the allergic reactions. Allergic reactions triggered by parenterally administered α-Gal sources appear immediately, but those triggered via the oral route appear with a latency of several hours. The α-Gal epitope is highly immunogenic to humans, apes and old-world monkeys, all of which produce anti-α-Gal antibodies of the IgM, IgA and IgG subclasses. Strong evidence suggests that in susceptible individuals, class switch to IgE occurs after several tick bites. In this review, we discuss the strong immunogenic role of the α-Gal epitope and its structural resemblance to the blood type B antigen. We emphasize the broad abundance of α-Gal in different foods and pharmaceuticals and the allergenicity of various α-Gal containing molecules. We give an overview of the association of tick bites with the development of AGS and describe innate and adaptive immune response to tick saliva that possibly leads to sensitization to α-Gal. We further discuss a currently favored hypothesis explaining the mechanisms of the delayed effector phase of the allergic reaction to α-Gal. We highlight AGS from a clinical point of view. We review the different clinical manifestations of the disease and the prevalence of sensitization to α-Gal and AGS. The usefulness of various diagnostic tests is discussed. Finally, we provide different aspects of the management of AGS. With climate change and global warming, the tick density is increasing, and their geographic range is expanding. Thus, more people will be affected by AGS which requires more knowledge of the disease.

Alpha-Gal IgE Prevalence Patterns in the United States: An Investigation of 3,000 Military Recruits

BACKGROUND

IgE to the oligosaccharide galactose-alpha-1,3-galactose (alpha-gal) is an important cause of allergic reactions to mammalian meat. The "alpha-gal syndrome" is strongly associated with a preceding history of tick bites and in the United States is most commonly reported in parts of the southeast, but there has been limited investigation into national alpha-gal sensitization patterns and the relevance of other risk factors.

OBJECTIVE

To systematically investigate alpha-gal IgE prevalence, regional patterns, and risk factors.

METHODS

Alpha-gal IgE was measured by ImmunoCAP in biobanked serum samples collected from 3000 service members who presented for intake to 1 of 10 military bases in the central/eastern United States. Alpha-gal IgE sensitization (cutoff 0.1 international units/mL) was related to home of record at enlistment.

RESULTS

Of the cohort, 2456 (81.9%) subjects were male, median age was 19 years (interquartile range: 18-22 years), and alpha-gal IgE was detected in 179 (6.0%). Home of record spanned all 50 states, with a median of 36 recruits per state (range: 3-261). The highest prevalence rates were in Arkansas (39%), Oklahoma (35%), and Missouri (29%), with several other southeastern states >10%. Granular mapping revealed sensitization patterns that closely mimicked county-level Amblyomma americanum reports and Ehrlichia chaffeensis infections. Sensitization was associated with male sex, rural residence, and White race in univariate and multivariable models.

CONCLUSIONS

In this systematic survey, the prevalence of alpha-gal IgE among incoming military personnel was 6.0%. There were significant regional differences, with an overall pattern consistent with the known range of the lone star tick (A. americanum) and highest frequency in an area including Arkansas, Oklahoma, and Missouri.

Gastrointestinal-isolated Distress is Common in Alpha-gal Allergic Patients on Mammalian Meat Challenge

BACKGROUND AND AIMS

Alpha-gal allergy causes a delayed reaction to mammalian meats and has been reported worldwide. Patients with the allergy may present with isolated gastrointestinal (GI) symptoms, but this phenotype is poorly understood.

METHODS

We pooled and analyzed symptoms and demographics of patients from two prospective cohorts of patients with a diagnosis of alpha-gal allergy who reacted after eating mammalian meat under observation. We compared the characteristics of patients who demonstrated GI-isolated symptoms on a challenge with those who exhibited symptoms outside the GI tract (skin, respiratory, and circulatory).

RESULTS

Among the 91 children and adult alpha-gal allergic patients who exhibited symptoms after oral challenge with mammalian meat, 72.5% experienced GI distress with one or more GI symptoms, which was the most frequent class of symptoms, compared with skin changes in 57.1% and respiratory distress in 5.5%. The most common GI symptoms were abdominal pain (71%) and vomiting (22.0%). GI-isolated symptoms occurred in 37 patients (40.7%) who reacted, and those patients reacted more quickly than patients who exhibited systemic symptoms (median onset of symptoms in GI-isolated group 90 min vs 120 min) and were more likely to be children than adults (relative risk=1.94, 95% CI: 1.04-3.63).

CONCLUSIONS

Isolated-GI distress occurred in 4 in every 10 alpha-gal allergic individuals who developed symptoms on oral food challenge with mammalian meat. Alpha-gal allergic patients, particularly children, may exhibit GI distress alone, and adult and pediatric gastroenterologists should be aware of the diagnosis and management of the allergy.

Oral immunotherapy in alpha-gal red meat allergy: Could specific IgE be a potential biomarker in monitoring management?

BACKGROUND

Oral immunotherapy (OIT) is a promising treatment for food allergies. Our aim was to establish the long-term safety and efficacy of a novel red meat (RM) OIT in galactose-alpha-1,3-galactose (alpha-gal) allergy in adults.

METHODS

Out of 20 patients with confirmed RM allergy, five (41.66%) underwent an early OIT, seven (58.33%) underwent a delayed protocol and eight patients who were not desensitized formed the patient control group. 15 and 27 day RM OIT for early-onset and delayed-onset alpha-gal allergy were administered, respectively. Desensitized patients were recommended to continue eating at least 100 g RM every day for 6 months and every other day in the following 6 months. After a year, the consumption was recommended 2/3 times in a week. Patients were followed up with skin tests with commercial beef and lamb extracts, fresh raw/cooked beef and lamb and cetuximab and also with serum alpha-gal specific Immunoglobulin-E (sIgE) in the first and fifth years.

RESULTS

All patients who underwent OIT became tolerant to RM. During the 5 year follow-up, the median alpha-gal sIgE concentration gradually decreased in nine patients who consumed RM uneventfully while remained unchanged in the control group (p = .016). In two patients, rare tick bites acted as inducers of hypersensitivity reactions with concomitant elevation of alpha-gal sIgE concentrations whereas one patient with low follow-up alpha-gal sIgE concentrations consumed RM uneventfully after frequent tick bites.

CONCLUSIONS

Our study showed the long-term safety and efficacy of alpha-gal OIT. Additionally, alpha-gal sIgE seems to be a potential biomarker to monitor OIT.

Diagnostic validity of specific immunoglobulin E levels to alpha-gal in alpha-gal syndrome: a cross-sectional analysis

BACKGROUND

The diagnosis of Alpha-gal Syndrome (AGS) is based on the presence of symptoms after being exposed to potential sources of alpha-gal together with values ​​of specific IgE (sIgE) to alpha-gal ≥ 0.1 kUA/L or ≥ 0.35 kUA/L. The aim of this study was to evaluate the diagnostic validity of sIgE levels to alpha-gal ≥ 0.1 kUA/L for identifying AGS.

METHODS

This was a cross-sectional analysis of adult patients with available data on sIgE levels to alpha-gal, classified into two groups according to the presence (Group 1) or absence (Group 2) of symptoms after being exposed to potential sources of alpha-gal. Values of sIgE to alpha-gal ≥ 0.1 kUA/l were considered a positive result. A descriptive analysis of internal and external validity parameters was performed in the entire population and adjusted by sex.

RESULTS

The study included 33 individuals in Group 1 and 65 in Group 2, with a mean age of around 47 years. The analysis of internal validity parameters revealed a high sensitivity, specificity, and positive probability ratio, with higher sensitivity in men and higher specificity in women. The analysis of external validity parameters showed a high negative predictive value and global value in all populations and both sexes. However, the positive predictive value was relatively high in men, but low in women.

CONCLUSIONS

Our results suggest that sIgE levels ≥ 0.1 kUA/L may be a useful tool for the diagnosis of AGS, although other factors and diagnostic techniques should also be considered.

Study protocol to investigate the efficacy of confocal laser endomicroscopy-based selective single-elimination diet over standard fivefold elimination diet in patients with endomicroscopically proven food intolerance: app-assisted, monocentric, double-blind, randomised and controlled trial in Germany

INTRODUCTION

Imprecise nutritional recommendations due to a lack of diagnostic test accuracy are a frequent problem for individuals with adverse reactions to foods but no precise diagnosis. Consequently, patients follow very broad and strict elimination diets to avoid uncontrolled symptoms such as diarrhoea and abdominal pain. Dietary limitations and the uncertainty of developing gastrointestinal symptoms after the inadvertent ingestion of food have been demonstrated to reduce the quality of life (QoL) of affected individuals and subsequently might increase the risk of malnutrition and intestinal dysbiosis. This trial aims to investigate the effects of a tailored diet based on the confocal laser endoscopy (CLE) examination result to limit the side effects of unspecific and broad elimination diets and to increase the patient's QoL.

METHODS AND ANALYSIS

The study is designed as a prospective, double-blind, monocentric, randomised and controlled trial conducted at the University Hospital of Schleswig-Holstein, Campus Lübeck, Germany. One hundred seventy-two patients with non-IgE-related food allergies and positive CLE results will be randomised to either a tailored diet or a standard fivefold elimination diet. The primary endpoints are the difference between the end and the start of the intervention in health-related QoL and the sum score of the severity of symptoms after 12 weeks. Key secondary endpoints are changes in the severity of symptoms, further QoL measurements, self-assessed state of health and number of days with a pathologically altered stool. Microbiome diversity and metabolome of stool, urine and blood will also be investigated. Safety endpoints are body composition, body mass index and adverse events.

ETHICS AND DISSEMINATION

The study protocol was accepted by the ethical committee of the University of Lübeck (AZ: 22-111) on 4 May2022. Results of the study will be published in peer-reviewed journals and presented at scientific meetings.

TRIAL REGISTRATION NUMBER

German Clinical Trials Register (DRKS00029323).

Alpha-gal syndrome: A review for the dermatologist

Alpha-gal syndrome (AGS) is an allergy to "red meat" and other mammalian products due to immunoglobulin E (IgE) antibodies against the sugar moiety galactose-alpha-1,3-galactose (alpha-gal), which is acquired following tick bites. Clinically, AGS presents with urticaria, abdominal pain, nausea, and occasionally anaphylaxis, and has wide inter- and intra-personal variability. Because symptom onset is generally delayed by 2 to 6 hours after meat consumption, AGS can be easily confused with other causes of urticaria and anaphylaxis, such as chronic spontaneous urticaria (CSU) and mast cell activation syndrome (MCAS). Diagnosis relies on a combination of clinical history, positive alpha-gal IgE blood testing and improvement on a mammalian-restricted diet. Management of the syndrome centers primarily on avoidance of mammalian meats (and occasionally dairy and other products) as well as acute management of allergic symptoms. Counseling about tick avoidance measures is also important as AGS will wane over time in many patients.

Clinical Presentation of Alpha-Gal Syndrome in Pediatric Gastroenterology and Response to Mammalian Dietary Elimination

INTRODUCTION

Alpha-gal syndrome is an immunoglobulin E (IgE)-mediated delayed hypersensitivity reaction to nonprimate mammalian products, which has a newly established gastrointestinal (GI) phenotype in adults. We assessed the GI presentation and treatment response in children.

METHODS

This is a retrospective study of patients presenting in a pediatric gastroenterology clinic tested for alpha-gal IgE.

RESULTS

Forty of 199 patients (20%) tested had a positive alpha-gal-specific IgE, with 77.5% reporting GI symptoms in isolation. Of the 30 that attempted dietary elimination, 8 (27%) experienced full resolution of symptoms.

DISCUSSION

Alpha-gal syndrome can present with isolated GI symptoms in children.

Alpha-Gal Sensitization in a US Screening Population Is Not Associated With a Decreased Meat Intake or Gastrointestinal Symptoms

INTRODUCTION

Patients with alpha-gal syndrome, a delayed reaction to mammalian meat, can present with isolated gastrointestinal (GI) symptoms. We aimed to estimate the frequency of alpha-gal sensitization in a Southeastern US population and determine the association between sensitization and mammalian product dietary intake or GI symptoms.

METHODS

We performed a cross-sectional study of participants who underwent a screening colonoscopy at our center between 2013 and 2015. We quantified serum alpha-gal immunoglobulin E antibodies in participants who were prospectively enrolled at screening colonoscopy and compared diet intake and lower GI symptoms reported in standardized questionnaires among those with elevated versus no alpha-gal IgE antibodies.

RESULTS

Alpha-gal IgE antibodies were common-31.4% of screening colonoscopy participants (127 of 404) had elevated serum alpha-gal IgE >0.1 kU/L. Alpha-gal-sensitized participants endorsed similar rates of abdominal pain compared with those without alpha-gal antibodies (33% vs 38%, adjusted odds ratio 0.9, 95% confidence interval 0.7-1.3). Mammalian meat consumption did not differ based on alpha-gal sensitization status (average 1.43 servings/d in sensitized subjects vs 1.50 in alpha-gal IgE-negative subjects, P = 0.9). Alpha-gal-sensitized participants with levels ≥10 (n = 21) were overrepresented in the lowest quartiles of mammalian meat consumption, but not among those with GI symptoms in general. Participants with high alpha-gal antibody levels >2 kU/L (n = 45) or ≥10 U/L (n = 21) did not have a reduced mean daily mammalian meat intake compared with seronegative people.

DISCUSSION

Elevated alpha-gal IgE antibodies were common and not associated with a reduced mammalian meat intake, abdominal pain, or diarrhea. Seropositivity did not predict symptomatic alpha-gal sensitization in this general screening population. Other host factors likely contribute to the phenotypic expression of alpha-gal syndrome.

Factors predicting the outcome of allergen-specific nasal provocation test in children with grass pollen allergic rhinitis

Background

Nasal provocation testing (NPT) is a reference methodology to identify the culprit allergen in patients with allergic rhinitis. Selecting the right allergen for NPT is particularly difficult in poly-sensitized patients with seasonal allergic rhinitis (SAR). Predictors of NPT outcomes may facilitate the proper use of this test or even substitute it.

Objective

To identify predictors of grass pollen NPT outcome from an array of clinical data, e-diary outcomes, and allergy test results in poly-sensitized pediatric patients with SAR.

Methods

Poly-sensitized, SAR patients with grass pollen allergy, participating in the @IT.2020 pilot project in Rome and Pordenone (Italy), participated in a baseline (T0) visit with questionnaires, skin prick testing (SPT), and blood sampling to measure total (ImmunoCAP, TFS, Sweden) and specific IgE antibodies to grass pollen extracts and their major allergenic molecules (ESEP, Euroimmun Labordiagnostika, Germany). During the pollen season, patients filled the AllergyMonitor® e-diary app measuring their symptoms, medication intake, and allergy-related well-being via the Visual Analogue Scale (VAS). After the pollen season (T1), patients answered clinical questionnaires and underwent a nasal provocation test (NPT) with grass pollen extract.

Results

We recruited 72 patients (age 14.3 ± 2.8 years, 46 males) sensitized to grass and/or other pollens, including olive (63; 87.5%) and pellitory (49; 68.1%). Patients positive to grass pollen NPT (61; 84.7%), compared to the negative ones, had worse VAS values in the e-diary, larger SPT wheal reactions, and higher IgE levels, as well as specific activity to timothy and Bermuda grass extracts, rPhl p 5 and nCyn d 1. A positive NPT to grass pollen was predicted by an index combining the specific activity of IgE towards Phl p 5 and Cyn d 1 (AUC: 0.82; p < 0.01; best cut-off ≥7.25%, sensitivity 70.5%, specificity: 90.9%). VAS results also predicted NPT positivity, although with less precision (AUC: 0.77, p < 0.01; best cut-off ≥7, sensitivity: 60.7%, specificity: 81.8%).

Conclusions

An index combining the specific activity of IgE to rPhl p 5 and nCyn d 1 predicted with moderate sensitivity and high specificity the outcome of a grass pollen NPT in complex, poly-sensitized pediatric patients with seasonal allergic rhinitis. Further studies are needed to improve the index sensitivity and to assess its usefulness for NPT allergen selection or as an alternative to this demanding test procedure.

AGA Clinical Practice Update on Alpha-Gal Syndrome for the GI Clinician: Commentary

DESCRIPTION

Alpha-gal syndrome is an emerging allergy first described in the early 2000s. The allergy can cause anaphylaxis, gastrointestinal (GI) symptoms, and skin changes one to several hours after ingestion of mammalian products. A GI phenotype that is increasingly recognized manifests with nonspecific symptoms like abdominal pain, diarrhea, nausea or vomiting without predominant skin, respiratory or circulatory symptoms. Though the syndrome has been reported on all continents except Antarctica, in the United States most reports are within the range of the Lone Star tick, extending from New York and Iowa to Texas and Florida. The purpose of this AGA Clinical Practice Update (CPU) Commentary is to increase awareness among gastroenterologists about the presentation and management of alpha-gal syndrome.

METHODS

This CPU commentary was commissioned and approved by the AGA Institute Clinical Practice Updates Committee (CPUC) and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership and underwent internal peer review by the CPUC and external peer review through standard procedures of Clinical Gastroenterology and Hepatology. This expert commentary incorporates important as well as recently published studies in this field, and it reflects the experiences of the authors. Formal ratings regarding the quality of evidence or strength of the presented considerations were not included since systematic reviews were not performed.

Clinical Use of the ImmunoCAP Inhibition Test in the Diagnosis of Meat Allergy Caused by a Tick Bite in an Adult Male with No Previous Atopic History

(1) Background: alpha-gal syndrome (AGS) is a serious, potentially life-threatening allergic reaction. This is a type of food allergy to red meat and other mammalian products (e.g., gelatin). In Poland, this problem seems to be rare or, more likely, very underdiagnosed. The diagnosis of AGS is difficult. It seems that the knowledge about this syndrome is insufficient. There are no effective diagnostic tools able to clearly diagnose this cross-reactive allergy. This paper presents the clinical application of a non-standard method in the diagnosis of a cross-reactive allergy using the example of AGS. (2) Methods: standard tests for in vitro allergy diagnostics and the non-standard ImmunoCAP inhibition test(IT) were carried out for serum collected from a patient with a red meat allergy. (3) Results: the serum concentration of anti-α-Gal IgE was very high (302 kUA/L), and IgE antibodies toanti-mammalian-meat allergens were found. The level of IgE antibodies to mammalian meat allergens decreased after blocking on α-GAL-CAP. The concentration of anti-α-Gal IgE decreased after blocking on CAPs coated with various mammalian meat allergens. Blocking with allergens of poultry meat did not affect the concentration of anti-α-Gal IgE. (4) Conclusions: the ImmunoCAP ITseems to be a useful tool in the diagnosis of cross-reactive allergies. Based on their clinical history and test results, the patient was diagnosed with AGS caused by a primary sensitization to α-Gal after a tick bite. This is the second case of AGS described in Poland and the first in Pomerania.

The epidemiology of food allergy in adults

The prevalence and awareness of food allergy (FA) among US adults is arguably at a historical high, both with respect to primary immunoglobulin E-mediated food hypersensitivity and other food-triggered conditions that operate through a variety of immunologic mechanisms (eg, pollen-FA syndrome, alpha-gal syndrome, food protein-induced enterocolitis syndrome, eosinophilic esophagitis). Worryingly, not only are many adults retaining childhood-onset food allergies as they age into adulthood, it seems that many adults are experiencing adult-onset allergies to previously tolerated foods, with correspondingly adverse physical, and psychological health impacts. Consequently, this review aims to summarize what is currently known about the epidemiology and population-level burden of FA among adult populations in North America and around the globe. This article also provides insights into the natural history of these conditions and what we need to know as we look to the future to support effective care and prevent FA.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Food Allergies and Alpha-gal Syndrome for the Gastroenterologist

PURPOSE OF REVIEW

Food allergies are typically not considered as a cause of gastrointestinal (GI) distress without additional allergic symptoms, apart from celiac disease and eosinophilic esophagitis. However, recent reports of patients with alpha-gal syndrome who presented with GI-only symptoms like abdominal pain, vomiting, and diarrhea challenge this paradigm. Alpha-gal syndrome is an IgE-mediated allergy characterized by delayed reactions after eating mammalian meat or mammalian-derived products that contain galactose-alpha-1,3-galactose (alpha-gal). The purpose of this review is to discuss our current understanding of food allergies, GI illness, and the GI manifestations of alpha-gal syndrome.

RECENT FINDINGS

Among Southeastern U.S. GI clinic patients who screened positive for serum alpha-gal IgE, a majority of patients reported significant symptom improvement on an alpha-gal-avoidant diet, suggesting that the allergy had played a role in their GI symptoms. Diagnosis of alpha-gal syndrome is typically made with concerning allergic symptoms, elevated alpha-gal specific IgE in the serum, and symptom improvement on an alpha-gal avoidant diet. Alpha-gal syndrome can cause a delayed allergic response that is increasingly recognized worldwide, including among patients with predominant GI symptoms.

Clinical and laboratory features of patients diagnosed with alpha-gal syndrome-2010-2019

BACKGROUND

Alpha-gal syndrome (AGS) is an IgE-mediated allergy to galactose-alpha-1,3-galactose. Clinical presentation ranges from hives to anaphylaxis; episodes typically occur 2-6 h after exposure to alpha-gal-containing products. In the United States, lone star tick bites are associated with the development of AGS. To characterize features of AGS, we evaluated a cohort of patients presenting for care at the University of North Carolina, focusing on symptoms, severity, and identifying features unique to specific alpha-gal-containing product exposures.

METHODS

We performed a chart review and descriptive analysis of 100 randomly selected patients with AGS during 2010-2019.

RESULTS

Median age at onset was 53 years, 56% were female, 95% reported White race, 86% reported a history of tick bite, and 75% met the criteria for anaphylaxis based on the involvement of ≥2 organ systems. Those reporting dairy reactions were significantly less likely to report isolated mucocutaneous symptoms (3% vs. 24%; ratio [95% CI]: 0.1 [0.1, 0.3]) than those who tolerated dairy, and were more likely to report gastrointestinal symptoms (79% vs. 59%; ratio [95% CI]: 1.3 [0.7, 2.6]), although this difference was not statistically significant. Dairy-tolerant patients demonstrated higher alpha-gal sIgE titers (as a percentage of total IgE) than dairy-reactive patients (GM 4.1 [95% CI: 2.7, 6.1] vs. GM 2.5 [95% CI: 1.3, 4.8], respectively; ratio -1.6 [95% CI: -1.0, 3.9]).

CONCLUSION

While tick exposure is common in the southern United States, nearly all AGS patients reported a tick bite. Gastrointestinal symptoms were prominent among those reporting reactions to dairy. Anaphylaxis was common, underscoring the severity and need to raise awareness of AGS among patients and providers.

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.

Cohort study of subclinical sensitization against galactose‐α‐1,3‐galactose in Japan: Prevalence and regional variations

Sensitization to galactose-α-1,3-galactose (α-Gal) leads to the development of α-Gal syndrome, which includes red meat allergy and cetuximab-induced anaphylaxis. Since tick bites represent the main cause of α-Gal sensitization, it was speculated that sensitization to α-Gal occurs throughout Japan. However, few cohort studies have investigated α-Gal sensitization in Japan. Therefore, we aimed to elucidate the subclinical sensitization rate to α-Gal in Japan. Sera were obtained from 300 participants without food or cetuximab allergy at Shimane University Hospital (Shimane prefecture), Tokyo Medical and Dental University Hospital (Tokyo metropolis), and Tohoku University Hospital (Miyagi prefecture). ImmunoCAP-bovine thyroglobulin (BTG), ImmunoCAP-beef, and IgE immunoblotting with cetuximab were performed to detect α-Gal-specific IgE. Clinical information was collected from participants using a questionnaire. The overall positivity rate of ImmunoCAP-BTG was 4.0% without significant inter-institute differences, whereas that for ImmunoCAP-beef was 9.7% with a significant inter-institute difference. Tokyo Medical and Dental University Hospital (19.0%) had the highest positivity rate. The positivity rate based on cetuximab IgE immunoblotting was 2.7%, without any significant inter-institute differences. The overall positivity rate for both ImmunoCAP-BTG and cetuximab immunoblotting was 2.0%, with a significant inter-institute difference; 5.0% of Shimane University Hospital was the highest. Two cases showed sensitization against the non-α-Gal epitope of cetuximab. The overall positivity rate for both ImmunoCAP-beef and cetuximab immunoblotting was 1.3%, without significant inter-institute differences. Male sex was associated with positive beef-specific IgE. The prevalence of subclinical sensitization to α-Gal is estimated at 2.0%-4.0% in Japan and may be higher in rural areas, supporting an association between tick bites and α-Gal sensitization. In contrast, the prevalence of subclinical sensitization to beef is 9.7% in Japan and is highest in Tokyo Metropolis, suggesting the presence of another IgE-binding epitope apart from α-Gal and another sensitization route in the sensitization to beef IgE.

Current and Future Strategies for the Diagnosis and Treatment of the Alpha-Gal Syndrome (AGS)

The α-Gal syndrome (AGS) is a pathognomonic immunoglobulin E (IgE)-mediated delayed anaphylaxis in foods containing the oligosaccharide galactose-α-1,3-galactose (α-Gal) such as mammalian meat or dairy products. Clinical presentation of AGS can also comprise immediate hypersensitivity due to anticancer therapy, gelatin-containing vaccines or mammalian serum-based antivenom. The IgE initial sensitization is caused by hard-bodied tick bites and symptomatic individuals typically develop delayed pruritus, urticaria, angioedema, anaphylaxis, malaise or gut-related symptoms. Due to inapparent presentation, delayed reactions and a wide variety of patients´ clinical history, the AGS diagnosis and treatment remain challenging. This review covers not only current diagnostic methods used for AGS such as the skin prick test (SPT), the oral food challenge (OFC), anti-α-Gal IgE levels measurement and the basophil activation test (BAT), but also potentially relevant next-generation diagnostic tools like the mast cell activation test (MAT), the histamine-release (HR) assay, omics technologies and model-based reasoning (MBR). Moreover, it focuses on the therapeutical medical and non-medical methods available and current research methods that are being applied in order to elucidate the molecular, physiological and immune mechanisms underlying this allergic disorder. Lastly, future treatment and preventive tools are also discussed, being of utmost importance for the identification of tick salivary molecules, with or without α-Gal modifications, that trigger IgE sensitivity as they could be the key for further vaccine development. Bearing in mind climate change, the tick-host paradigm will shift towards an increasing number of AGS cases in new regions worldwide, which will pose new challenges for clinicians in the future.

Anaphylaxis to Excipients in Current Clinical Practice: Evaluation and Management

Excipients are the inactive ingredients in a drug or product that help to stabilize, preserve, or enhance the pharmacokinetics and bioavailability of the active ingredients. Excipient allergy is rare and hence often missed or misdiagnosed due to lack of awareness of the need to carefully review all drug ingredients. For the patient, excipient allergy can be frightening and potentially disruptive to health care delivery. This narrative review provides a clinically oriented, international, collaborative perspective on excipient allergy testing, management of future health care safety, limitations in our testing modalities, and barriers to optimal care.

The Quantification of IgG Specific to α-Gal Could Be Used as a Risk Marker for Suffering Mammalian Meat Allergy

The alpha-Gal Syndrome is a delayed meat allergy characterized by the presence of sIgE against α-Gal epitope. It is known that the α-Gal present in tick saliva induces the sensitization to this epitope ending in the production of sIgG and sIgE to α-Gal. It could be considered that the more times a person is bitten by tick species, the higher the probability of making the switch from sIgG to sIgE to α-Gal and developing allergy, but it is no clear when the switch occurs. To determine the likelihood that a subject bitten by ticks but without AGS be at risk of developing this allergy, we quantified the levels of sIgG to α-Gal by an automated system (ImmunoCap). To stablish a cut-off value for sIgG to α-Gal, a receiving operating curve (ROC) was constructed. The statistical analysis demonstrated that the risk of suffering AGS in individuals bitten by ticks was 35% when the sIgG to α-Gal was greater than or equal to 40 µg/mL. Our data indicate that the sIgG values against α-Gal could be used as a prognostic marker for developing mammalian meat allergy.

Where's the Beef? Understanding Allergic Responses to Red Meat in Alpha-Gal Syndrome

Alpha-gal syndrome (AGS) describes a collection of symptoms associated with IgE-mediated hypersensitivity responses to the glycan galactose-alpha-1,3-galactose (alpha-gal). Individuals with AGS develop delayed hypersensitivity reactions, with symptoms occurring >2 h after consuming mammalian ("red") meat and other mammal-derived food products. The mechanisms of pathogenesis driving this paradigm-breaking food allergy are not fully understood. We review the role of tick bites in the development of alpha-gal-specific IgE and highlight innate and adaptive immune cells possibly involved in alpha-gal sensitization. We discuss the impact of alpha-gal glycosylation on digestion and metabolism of alpha-gal glycolipids and glycoproteins, and the implications for basophil and mast cell activation and mediator release that generate allergic symptoms in AGS.

Alpha-Gal Syndrome in Children: Peculiarities of a "Tick-Borne" Allergic Disease

The alpha-gal syndrome is an allergic syndrome that comprises two clinical pictures: an immediate hypersensitivity to drugs containing alpha-gal and a delayed hypersensitivity to the ingestion of red mammalian meat. This allergic syndrome is often under-recognized, and patients are mislabeled with diagnosis as spontaneous urticaria or idiopathic anaphylaxis. Even though less frequently, children could also be of interest, especially in tick-endemic areas. In most cases, a positive anamnesis for tick bites months before the onset of symptoms is recorded. The clinical manifestations could range from asymptomatic cases to severe anaphylaxis. The most frequently used diagnostic test is the determination of specific IgE for alpha-gal. Oral provocation test is usually reserved to unclear cases or to verify tolerance after diet. No long-term follow-up studies have been published, although an elimination diet could lead to a decrease of specific IgE for alpha-gal and a possible reintroduction of some avoided foods. This paper provides a literature review, focused on pediatric age, and an evaluation of available diagnostic tests. We analyze the correlation between tick bites and symptom onset and unfold the different clinical pictures to help clinicians to promptly recognized this syndrome. Lastly, we address unmet needs in this specific allergy.

The α-Gal Syndrome and Potential Mechanisms

The α-Gal syndrome is a complex allergic disease characterized by the development of specific IgE antibodies against the carbohydrate galactose-α-1,3-galactose (α-Gal), an oligosaccharide present in cells and tissues of non-primate mammals. Individuals with IgE antibodies to α-Gal suffer from a delayed form of anaphylaxis following red meat consumption. There are several features that make the α-Gal syndrome such a unique allergic disease and distinguish it from other food allergies: (1) symptoms causing IgE antibodies are directed against a carbohydrate moiety, (2) the unusual delay between the consumption of the food and the onset of the symptoms, and (3) the fact that primary sensitization to α-Gal occurs via tick bites. This review takes a closer look at the immune response against α-Gal, in healthy and in α-Gal allergic individuals. Furthermore, the similarities and differences between immune response against α-Gal and against the other important glycan moieties associated with allergies, namely cross-reactive carbohydrate determinants (CCDs), are discussed. Then different mechanisms are discussed that could contribute to the delayed onset of symptoms after consumption of mammalian meat. Moreover, our current knowledge on the role of tick bites in the sensitization process is summarized. The tick saliva has been shown to contain proteins carrying α-Gal, but also bioactive molecules, such as prostaglandin E2, which is capable of stimulating an increased expression of anti-inflammatory cytokines while promoting a decrease in the production of proinflammatory mediators. Together these components might promote Th2-related immunity and trigger a class switch to IgE antibodies directed against the oligosaccharide α-Gal. The review also points to open research questions that remain to be answered and proposes future research directions, which will help to get a better understanding and lead to a better management of the disease.

Food allergy across the globe

The prevalence of food allergy (FA) is increasing in some areas of the globe, highlighting the need for better strategies for prevention, diagnosis, and therapy. In the last few decades, we have made great strides in understanding the causes and mechanisms underlying FAs, prompting guideline updates. Earlier guidelines recommended avoidance of common food allergens during pregnancy and lactation and delaying the introduction of allergenic foods in children aged between 1 and 3 years. Recent guidelines for allergy prevention recommend consumption of a healthy and diverse diet without eliminating or increasing the consumption of allergenic foods during pregnancy or breast-feeding. Early introduction of allergenic foods is recommended by most guidelines for allergy prevention after a period of exclusive breast-feedng (6 months [World Health Organization] or 4 months [European Academy of Allergy and Clinical Immunology]). New diagnostics for FA have been developed with varied availability of these tests in different countries. Finally, the first oral immunotherapy drug for FA was approved by the US Food and Drug Administration and European Medicines Agency in 2020. In this review, we will address the global prevalence of FA, our current understanding of the causes of FA, and the latest guidelines for preventing, diagnosing, and treating FA. We will also discuss similarities and differences between FA guidelines.

Successful Treatment for Alpha Gal Mammal Product Allergy Using Auricular Acupuncture: A Case Series

Introduction: Alpha gal syndrome (AGS) is an acquired allergy to mammalian products correlates with a tick bite(s) that appears to cause immune sensitization to an oligosaccharide in meat. Most publications on AGS describe no management other than avoidance of the offending agent(s). The objective of this study is to describe 2 populations of subjects who underwent Soliman Auricular Allergy Treatment (SAAT) for significant AGS meat and/or dairy allergy. Methods: We performed a retrospective review of subjects treated at 2 different medical clinics that apply the same method of auricular acupuncture (SAAT) to AGS patients. Results: A total of 137 patients presented to the 2 sites included in this study. The majority of patients were mammal product eaters before AGS; however, at the time of treatment only 7.3% of individuals (n = 10) actively consumed mammal products. Most subjects were reactive to beef (n = 135) and dairy (n = 95). The most common organ system involved in prior allergic reactions associated with AGS were gastrointestinal (n = 82, 59.9%) and dermatologic (n = 61, 44.5%). For those individuals with available outcome data on SAAT effectiveness (n = 126), 121 (96%) patients indicated that their symptoms were in remission after SAAT. Five individuals indicated that their symptoms were not in remission. Eleven individuals were unsure of treatment response or unable to be reached for follow-up. Conclusion: The SAAT method showed effectiveness in the large majority of patients. No adverse reactions were noted as a result of auricular acupuncture. This alternative medicine approach to AGS management should be further studied in prospective trials with laboratory confirmation both before and after the procedure. This low-risk treatment shows promise in treating a medical condition that causes distress in an increasing number of patients.

Allergy to Mammalian Meat Linked to Alpha-Gal Syndrome Potentially After Tick Bite in the Amazon: A Case Series

The past decade has seen the emergence of a new type of food allergy occurring after ingestion of mammalian meat. This allergy is related to immunoglobulin (Ig)E specific for galactose-alpha-1,3 galactose (α-Gal). Originally described in the United States in 2009, other cases have subsequently been described in Australia and in Europe, but still very few in Latin America. The purpose of this study was to show the existence of this pathology in French Guiana and to describe the historical, clinical, and biological characteristics of these patients. Patients reporting an allergy to mammalian meat were included between September 2017 and August 2019. Eleven patients were included, nine of whom exhibited digestive symptoms; four, urticaria reactions; three, respiratory reactions; and five angioedema. The time between ingestion of red meat and reaction varied between 1.5 and 6 hours. The implicated meats were most often beef and pork. All patients had been regularly exposed to tick bites before the appearance of symptoms. All the samples (n = 7) were positive for anti-α-Gal anti-mammalian meats IgE. All the patients were Caucasian French expatriates. This study confirms the presence of this new entity in French Guiana and is the largest reported in Latin America. Our results do not clearly allow us to state that tick bites are the cause of this allergy, but all patients reported being exposed regularly to these arthropods.

Integration of in vitro allergy test results and ratio analysis for the diagnosis and treatment of allergic patients (INTEGRA)

The introduction of molecular diagnosis into routine clinical practice has substantially improved the diagnosis and management of allergic patients by allowing clinicians to precisely identify the allergenic molecule responsible for immunoglobulin E (IgE)-mediated allergies. However, it can be challenging to accurately interpret the results of molecular assays, partly due to the limited evidence base. In this context, a panel of experts with extensive experience in interpreting in vitro measures of total and serum specific IgE reviewed the available scientific evidence. After this review, the panel selected a series of representative case studies to demonstrate how determination of specific and total IgE values and the relationship between them (ratio analysis) can add value to the diagnostic process by more precisely defining the patient's sensitization profile. Finally, the experts developed a series of recommendations on the clinical application of ratio analysis to optimize and complement the classical approach to allergy diagnosis.

Carbohydrate epitopes currently recognized as targets for IgE antibodies

Until recently, glycan epitopes have not been documented by the WHO/IUIS Allergen Nomenclature Sub-Committee. This was in part due to scarce or incomplete information on these oligosaccharides, but also due to the widely held opinion that IgE to these epitopes had little or no relevance to allergic symptoms. Most IgE-binding glycans recognized up to 2008 were considered to be "classical" cross-reactive carbohydrate determinants (CCD) that occur in insects, some helminths and throughout the plant kingdom. Since 2008, the prevailing opinion on lack of clinical relevance of IgE-binding glycans has been subject to a reevaluation. This was because IgE specific for the mammalian disaccharide galactose-alpha-1,3-galactose (alpha-gal) was identified as a cause of delayed anaphylaxis to mammalian meat in the United States, an observation that has been confirmed by allergists in many parts of the world. Several experimental studies have shown that oligosaccharides with one or more terminal alpha-gal epitopes can be attached as a hapten to many different mammalian proteins or lipids. The classical CCDs also behave like haptens since they can be expressed on proteins from multiple species. This is the explanation for extensive in vitro cross-reactivity related to CCDs. Because of these developments, the Allergen Nomenclature Sub-Committee recently decided to include glycans as potentially allergenic epitopes in an adjunct section of its website (www.allergen.org). In this article, the features of the main glycan groups known to be involved in IgE recognition are revisited, and their characteristic structural, functional, and clinical features are discussed.

Ascaris lumbricoides and ticks associated with sensitization to galactose α1,3-galactose and elicitation of the alpha-gal syndrome

BACKGROUND

IgE to galactose alpha-1,3 galactose (alpha-gal) causes alpha-gal syndrome (delayed anaphylaxis after ingestion of mammalian meat). Development of sensitization has been attributed to tick bites; however, the possible role of other parasites has not been well studied.

OBJECTIVE

Our aims were to assess the presence, relative abundances, and site of localization of alpha-gal-containing proteins in common ectoparasites and endoparasites endemic in an area of high prevalence of alpha-gal syndrome, as well as to investigate the ability of ascaris antigens to elicit a reaction in a humanized rat basophil in vitro sensitization model.

METHODS

Levels of total IgE, Ascaris-specific IgE, and alpha-gal IgE were measured in sera from patients with challenge-proven alpha-gal syndrome and from controls without allergy. The presence, concentration, and localization of alpha-gal in parasites were assessed by ELISA, Western blotting, and immunohistochemistry. The ability of Ascaris lumbricoides antigen to elicit IgE-dependent reactivity was demonstrated by using the RS-ATL8 basophil reporter system.

RESULTS

Alpha-gal IgE level correlated with A lumbricoides-specific IgE level. Alpha-gal protein at 70 to 130 kDa was detected in A lumbricoides at concentrations higher than those found in Rhipicephalus evertsi and Amblyomma hebraeum ticks. Immunohistochemistry was used to localize alpha-gal in tick salivary acini and the helminth gut. Non-alpha-gal-containing A lumbricoides antigens activated RS-ATL8 basophils primed with serum from subjects with alpha-gal syndrome.

CONCLUSION

We demonstrated the presence, relative abundances, and site of localization of alpha-gal-containing proteins in parasites. The activation of RS-ATL8 IgE reporter cells primed with serum from subjects with alpha-gal syndrome on exposure to non-alpha-gal-containing A lumbricoides proteins indicates a possible role of exposure to A lumbricoides in alpha-gal sensitization and clinical reactivity.

Anti-glycan antibodies: roles in human disease

Carbohydrate-binding antibodies play diverse and critical roles in human health. Endogenous carbohydrate-binding antibodies that recognize bacterial, fungal, and other microbial carbohydrates prevent systemic infections and help maintain microbiome homeostasis. Anti-glycan antibodies can have both beneficial and detrimental effects. For example, alloantibodies to ABO blood group carbohydrates can help reduce the spread of some infectious diseases, but they also impose limitations for blood transfusions. Antibodies that recognize self-glycans can contribute to autoimmune diseases, such as Guillain-Barre syndrome. In addition to endogenous antibodies that arise through natural processes, a variety of vaccines induce anti-glycan antibodies as a primary mechanism of protection. Some examples of approved carbohydrate-based vaccines that have had a major impact on human health are against pneumococcus, Haemophilus influeanza type b, and Neisseria meningitidis. Monoclonal antibodies specifically targeting pathogen associated or tumor associated carbohydrate antigens (TACAs) are used clinically for both diagnostic and therapeutic purposes. This review aims to highlight some of the well-studied and critically important applications of anti-carbohydrate antibodies.

T and B Lymphocyte Transcriptional States Differentiate between Sensitized and Unsensitized Individuals in Alpha-Gal Syndrome

The mechanisms of pathogenesis driving alpha-gal syndrome (AGS) are not fully understood. Differences in immune gene expression between AGS individuals and non-allergic controls may illuminate molecular pathways and targets critical for AGS development. We performed immune expression profiling with RNA from the peripheral blood mononuclear cells (PBMCs) of seven controls, 15 AGS participants, and two participants sensitized but not allergic to alpha-gal using the NanoString nCounter PanCancer immune profiling panel, which includes 770 genes from 14 different cell types. The top differentially expressed genes (DEG) between AGS subjects and controls included transcription factors regulating immune gene expression, such as the NFκB pathway (NFKBIA, NFKB2, REL), antigen presentation molecules, type 2/allergic immune responses, itch, and allergic dermatitis. The differential expression of genes linked to T and B cell function was also identified, including transcription factor BCL-6, markers of antigen experience (CD44) and memory (CD27), chemokine receptors (CXCR3, CXCR6), and regulators of B-cell proliferation, cell cycle entry and immunoglobulin production (CD70). The PBMCs from AGS subjects also had increased TNF and IFN-gamma mRNA expression compared to controls. AGS is associated with a distinct gene expression profile in circulating PBMCs. DEGs related to antigen presentation, antigen-experienced T-cells, and type 2 immune responses may promote the development of alpha-gal specific IgE and the maintenance of AGS.

IgE-mediated food allergy throughout life

Food allergy (FA) has become an increasing problem throughout the world. Over the last 2 decades, the frequency of FA has increased in both children and adults. The prevalence differs according to the research methodology, age, and geographic regions, ranging between 2.0% and 10.0%. The most common form of FA is immunoglobulin E (IgE)-mediated FA. In this form, patients may present with life-threatening conditions, such as anaphylaxis, or milder conditions, such as urticaria, angioedema, sneezing, and nausea alone. The gold standard in the diagnosis of FA is oral provocation tests. Epidermal skin prick tests and specific IgE measurements, as well as component-resolved diagnostic techniques are helpful in the diagnosis and follow-up of patients. In this review, the epidemiology, diagnosis, follow-up, and prognosis of IgE-mediated FA in children and adults were discussed and some specific forms of FA, such as pollen FA syndrome, alpha-gal allergy, and food-dependent exercise-induced anaphylaxis were explained.