Alpha-gal is a possible target of IgE-mediated reactivity to antivenom

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.

Flow-based basophil activation test in immediate drug hypersensitivity. An EAACI task force position paper

Diagnosing immediate drug hypersensitivity reactions (IDHRs) can pose a significant challenge and there is an urgent need for safe and reliable tests. Evidence has emerged that the basophil activation test (BAT), an in vitro assay that mirrors the in vivo response, can be a complementary test for many drugs. In this position paper, members of Task Force (TF) "Basophil activation test in the evaluation of Drug Hypersensitivity Reactions" from the European Academy of Allergy and Clinical Immunology (EAACI) present the data from a survey about the use and utility of BAT in IDHRs in Europe. The survey results indicate that there is a great interest for using BAT especially for diagnosing IDHRs. However, there are still main needs, mainly in the standardization of the protocols. Subsequently consensus-based recommendations were formulated for: (i) Technical aspects of BAT in IDHRs including type of sample, management of drugs, flow cytometry protocols, interpretation of the results; and (ii) Drug-specific aspects that should be taken into account when performing BAT in relation to betalactams, neuromuscular blocking agents, fluoroquinolones, chlorhexidine, opioids, radio contrast media, chemotherapeutics, biological agents, nonsteroidal anti-inflammatory drugs, COVID vaccine, and excipients. Moreover, aspects in the evaluation of pediatric population have also been considered. All this indicates that BAT offers the clinician and laboratory a complementary tool for a safe diagnostic for IDHRs, although its place in the diagnostic algorithm depends on the drug class and patient population (phenotype, geography, and age). The standardization of BAT is important for generalizing this method beyond the individual laboratory.

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 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.

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.

A novel monoclonal IgG1 antibody specific for Galactose-alpha-1,3-galactose questions alpha-Gal epitope expression by bacteria

The alpha-Gal epitope (α-Gal) with the determining element galactose-α1,3-galactose can lead to clinically relevant allergic reactions and rejections in xenotransplantation. These immune reactions can develop because humans are devoid of this carbohydrate due to evolutionary loss of the enzyme α1,3-galactosyltransferase (GGTA1). In addition, up to 1% of human IgG antibodies are directed against α-Gal, but the stimulus for the induction of anti-α-Gal antibodies is still unclear. Commensal bacteria have been suggested as a causal factor for this induction as α-Gal binding tools such as lectins were found to stain cultivated bacteria isolated from the intestinal tract. Currently available tools for the detection of the definite α-Gal epitope, however, are cross-reactive, or have limited affinity and, hence, offer restricted possibilities for application. In this study, we describe a novel monoclonal IgG1 antibody (27H8) specific for the α-Gal epitope. The 27H8 antibody was generated by immunization of Ggta1 knockout mice and displays a high affinity towards synthetic and naturally occurring α-Gal in various applications. Using this novel tool, we found that intestinal bacteria reported to be α-Gal positive cannot be stained with 27H8 questioning whether commensal bacteria express the native α-Gal epitope at all.

Transchromosomic bovines (TcB)-derived broadly neutralizing antibodies as potent biotherapeutics to counter important emerging viral pathogens with a special focus on SARS-CoV-2, MERS-CoV, Ebola, Zika, HIV-1 and Influenza A virus

Historically, passive immunotherapy is an approved approach for protecting and treating humans against various diseases when other alternative therapeutic options are unavailable. Human polyclonal antibodies (hpAbs) can be made from convalescent human donor serum, although it is considered limited due to pandemics and the urgent requirement. Additionally, polyclonal antibodies (pAbs) could be generated from animals, but they may cause severe immunoreactivity and, once "humanized," may have lower neutralization efficiency. Transchromosomic bovines (TcBs) have been developed to address these concerns by creating robust neutralizing hpAbs, which are useful in preventing and/or curing human infections in response to hyperimmunization with vaccines holding adjuvants and/or immune stimulators over an extensive period. Unlike other animal‐derived pAbs, potent hpAbs could be promptly produced from TcB in large amounts to assist against an outbreak scenario. Some of these highly efficacious TcB‐derived antibodies have already neutralized and blocked diseases in clinical studies. Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has numerous variants classified into variants of concern (VOCs), variants of interest (VOIs), and variants under monitoring. Although these variants possess different mutations, such as N501Y, E484K, K417N, K417T, L452R, T478K, and P681R, SAB‐185 has shown broad neutralizing activity against VOCs, such as Alpha, Beta, Gamma, Delta, and Omicron variants, and VOIs, such as Epsilon, Iota, Kappa, and Lambda variants. This article highlights recent developments in the field of bovine‐derived biotherapeutics, which are seen as a practical platform for developing safe and effective antivirals with broad activity, particularly considering emerging viral infections such as SARS‐CoV‐2, Ebola, Middle East respiratory syndrome coronavirus, Zika, human immunodeficiency virus type 1, and influenza A virus. Antibodies in the bovine serum or colostrum, which have been proved to be more protective than their human counterparts, are also reviewed.

[Alpha-gal syndrome : Overview of clinical presentation and pathophysiology]

Das Alpha-Gal-Syndrom gehört zu den spannendsten Entdeckungen in der Allergologie der letzten 15 Jahre und wird ausgelöst durch spezifisches Immunglobulin E (sIgE) gegen den für Menschen immunogenen Zucker Galaktose-α‑1,3‑Galaktose (Alpha-Gal). Säugetierfleisch, Milch und daraus hergestellte Nahrungsmittel enthalten Alpha-Gal und können zu Anaphylaxien führen. Auch Arzneimittel und Medizinprodukte aus Säugetiergewebe können allergen sein. Zeckenstiche gelten als Hauptquelle einer Induktion von Alpha-Gal-sIgE. Ziel dieses Beitrags ist es, einen Überblick über den Stand des Wissens zum klinischen Bild und zu pathophysiologischen Konzepten zu geben.

Bovine γ-globulin, lactoferrin, and lactoperoxidase are relevant bovine milk allergens in patients with α-Gal syndrome

BACKGROUND

Mammalian meat is the most common trigger of the allergic reactions in patients with α-Gal syndrome (AGS). Milk and dairy, although less often, also cause a significant number of allergic manifestations. The aim of this study was to identify α-Gal-containing bovine milk proteins with allergenic properties among AGS patients.

METHODS

Thirty-eight AGS patients with IgE to milk were included in the study. Milk proteins were analyzed for the presence of α-Gal and for binding by patients' IgE using immunoblot, ImmunoCAP, and inhibition ELISA. Allergenicity of milk and milk proteins was assessed by basophil activation test.

RESULTS

More than half of the AGS patients reported allergic reactions to milk or dairy products. Bovine γ-globulin (BGG), lactoferrin (LF), and lactoperoxidase (LPO) were identified as α-Gal carrying proteins which were recognized by AGS patients' IgE. Whey mirrored the anti-α-Gal and IgE reactivity of BGG, LF, and LPO. Eighty-nine percent of the patients displayed IgE to BGG, 91% to LF, and 57% to LPO. Inhibition of α-Gal-specific IgE binding was achieved by BGG, LF, LPO, and whey. These proteins also activated AGS patients' basophils. Interestingly, at lower concentrations, LF was the most potent inhibitor of IgE binding, and the most potent activator of basophils.

CONCLUSION

BGG, LF, and LPO were all found to be relevant milk α-Gal-containing glycoproteins that bound AGS patients' IgE antibodies and activated their basophils. These proteins are probably involved in the allergic reactions to milk in AGS patients. LPO was for the first time shown to be an allergen.

Livestock herding and Fulani ethnicity are a combined risk factor for development of early adverse reactions to antivenom treatment: Findings from a cross-sectional study in Nigeria

Background

Adverse reactions to antivenom considerably complicate the clinical management of snakebite envenomed patients because it necessitates a temporary suspension of life-saving antivenom, increases costs and can compromise patient outcomes. This study sought to explore the association between cattle-herding occupation and ethnic group and the occurrence of early adverse reactions to antivenom.

Methods

This cross-sectional study was conducted between the 25th April and 11th July 2011 at the Kaltungo General Hospital in north east Nigeria. The exposure variable of cattle-herding occupation showed a strong correlation with the ethnic group variable, thus these were combined into a new variable with three categories (Fulani and herder, either Fulani or herder, and neither Fulani nor herder). The outcome variable was the occurrence of early adverse reactions, defined as any new symptoms occurring within 6 hours of antivenom administration. Odds Ratios were estimated using multivariable logistic regression models controlling for potential confounders.

Results

Among 231 envenomed snakebite victims, the overall incidence of early adverse reactions was 11.9% (95% confidence intervals: 8.0–16.9%). Patients who were Fulani and herders had a higher incidence of early adverse reactions compared to patients who were neither Fulani nor herders (20% vs 5.7%). After adjusting for age and gender, victims who were Fulani and herders were 5.9 times more likely to have an early adverse reaction, compared to victims who were neither Fulani nor herders (95% CI: 1.88–18.59; p = 0.002).

Interpretation

To the best of our knowledge, this is the first study to provide evidence of higher odds of early adverse reactions among patients from a particular occupation and/or ethnic group. We recommend that snake envenomed patients of Fulani origin be especially closely monitored for adverse reactions, that hospitals receiving these patients be appropriately resourced to manage both envenoming and adverse reactions and that premedication with adrenaline should be considered. Our findings provide an argument for speculation on the influence of immunological or lifestyle-related differences on the occurrence of early adverse reactions to antivenom.

Antivenom is the first-choice treatment of systemic snake envenoming that annually affects between 1.8–2.7 million victims globally. Access to antivenom is especially poor for those in greatest need because they typically reside in impoverished, rural tropical communities dependent upon health facilities with limited resources. In addition, clinical treatment of snakebite victims is further complicated by early adverse reactions (EARs) to antivenom-treatment. The causes of antivenom-associated EARs are poorly understood and under-researched. Despite antivenom producers instituting costly remedial manufacturing steps (removal of pyrogens and other impurities) to make their products safer, EARs still affect a high proportion of antivenom-treated patients. Instigated by anecdotal observations to the corresponding author from clinicians in rural Nigerian hospitals that snakebite victims of cattle-herding occupation, and especially those of Fulani ethnicity, suffer more frequent EARs than other groups, this cross-sectional study identified that risks of developing EARs to antivenom treatment include the ethnicity and pastoral lifestyle of snakebite patients. To our knowledge, this is the first study to identify that EARs to antivenom-treatment include factors associated with the victim, as well as factors related to the antivenom itself. We emphasise the need for more research on the causes of adverse reactions to antivenom so that strategies to reduce incidence can be implemented.

Comparative immunogenicity of decellularized wild type and alpha 1,3 galactosyltransferase knockout pig lungs

Decellularized pig lungs recellularized with human lung cells offer a novel approach for organ transplantation. However, the potential immunogenicity of decellularized pig lungs following exposure to human tissues has not been assessed. We found that exposure of native lungs from wildtype and transgenic pigs lacking alpha (1,3)-galactosyltransferase (α-gal KO) to sera from normal healthy human volunteers demonstrated similar robust IgM and IgG immunoreactivity, comparably decreased in decellularized lungs. Similar results were observed with sera from patients who had previously undergone transcutaneous porcine aortic valve replacement (TAVR) or from patients with increased circulating anti-α-gal IgE antibodies (α-gal syndrome). Depleting anti-α-gal antibodies from the sera demonstrated both specificity of α-gal immunoreactivity and also residual immunoreactivity similar between wildtype and α-gal KO pig lungs. Exposure of human monocytes and macrophages to native wildtype lungs demonstrated greater induction of M2 phenotype than native α-gal KO pig lungs, which was less marked with decellularized lungs of either type. Overall, these results demonstrate that native wildtype and α-gal KO pig lungs provoke similar immune responses that are comparably decreased following decellularization. This provides a further platform for potential use of decellularized pig lungs in tissue engineering approaches and subsequent transplantation schemes but no obvious overall immunologic advantage of utilizing lungs obtained from α-gal KO pigs.

Gelatin-Containing Vaccines for Varicella, Zoster, Measles, Mumps, and Rubella Induce Basophil Activation in Patients with Alpha-Gal Syndrome

BACKGROUND

The alpha-gal syndrome (AGS) describes a new type I allergy entity to the carbohydrate epitope galactose-α-1,3-galactose (alpha-gal), which is mainly found in mammalian food products (e.g., beef, pork, and venison). Apart from meat products, alpha-gal can also be found in products containing gelatin of bovine or porcine origin. Recent case reports pointed to severe anaphylaxis in patients suffering from AGS after vaccination with vaccines containing hydrolyzed gelatin. It was the objective of this study to evaluate if basophil activation tests (BATs) performed with such vaccines were positive in patients with AGS.

METHODS

BAT was performed with different dilutions of a gelatin-containing measles, mumps, and rubella (MMR) live vaccine; an attenuated varicella (V) vaccine; an attenuated V-zoster (VZ) vaccine; a MMR live vaccine not containing gelatin (non-gelatin MMR vaccine) in 2 patients with confirmed AGS, 2 patients highly suspicious for AGS, and 2 healthy individuals without any previous medical history for allergies.

RESULTS

All patients showed strongly positive results for all gelatin-containing vaccines (MMR vaccine, V vaccine, and VZ vaccine). Non-gelatin MMR vaccine was negative. The 2 healthy controls did not show any basophil activation.

CONCLUSIONS

Gelatin-containing vaccines should be administered with caution or avoided in patients with AGS because of their high potential to activate basophils indicating a risk for anaphylaxis. Also, BAT is a useful additional tool when it comes to screening for potentially high-risk alpha-gal-containing drugs.

Serum IgE against galactose-alpha-1,3-galactose is common in Laotian patients with snakebite envenoming but not the major trigger for early anaphylactic reactions to antivenom

Snake antivenom is the only specific treatment for snakebite envenoming, but life-threatening anaphylaxis is a severe side effect and drawback for the use of these typically mammalian serum products. The present study investigates the hypotheses whether serum IgE antibodies against the epitope galactose-alpha-1,3-galactose (α-gal) located on the heavy chain of non-primate mammalian antibodies are a possible cause for hypersensitivity reactions to snake antivenom. Serum samples from 55 patients with snakebite envenoming were obtained before administration of snake antivenom and tested for serum IgE (sIgE) against α-gal and total IgE. Early anaphylactic reactions (EARs) during the first 3 h after antivenom administration were classified into mild, moderate or severe and correlated with the presence of sIgE against α-gal. Fifteen (27%) out of 55 patients (37 male, 18 female, median 34 years, range 9-90 years) developed EARs after antivenom administration. Eleven, three and one patients had mild, moderate and severe EARs, respectively. Serum IgE against α-gal was detected in 17 patients (31%); in five (33%) out of 15 patients with EARs and in 12 (30%) out of 40 patients without EAR (Odds Ratio = 1.2; 95%-confidence interval: 0.3-4.2) with no correlation to severity. Although the prevalence of serum IgE against α-gal was high in the study population, very high levels of total IgE in the majority of patients question their clinical relevance and rather indicate unspecific sIgE binding instead of allergy. Lack of correlation between α-gal sIgE and EARs together with significantly increased total IgE levels suggest that sIgE against α-gal is not the major trigger for hypersensitivity reactions against snake antivenom.

Alpha-gal syndrome: An emerging cause of food and drug allergy

Alpha-gal syndrome (AGS) describes a wide spectrum of hypersensitivity reactions mediated by specific IgE to the α-gal epitope (galactose-α-1,3-galactose) ubiquitously expressed on glycolipids/glycoproteins of most mammals. This fascinating new entity has completely changed the paradigms of allergy as allergic response is directed against an oligosaccharide and the reactions can be both immediate and delayed. They appear to be stimulated only by tick bites which induce production of α-gal specific IgE antibodies that lead to (at times fatal) hypersensitivity response. AGS is completely different to previously described anaphylaxis to tick saliva. It provides unique insight into the interplay between different arms of the immune system and the role of ectoparasites in the development of anaphylaxis to food and medication in patients at risk of tick bites including travellers. This review summarises recent advances in our understanding of its clinical presentation, pathomechanism and role of various tick species in the development of AGS.

Spatial distribution of alpha-gal in Ixodes ricinus - A histological study

Alpha-gal syndrome is a complex allergic disease in humans that is caused by specific IgE (sIgE) against the carbohydrate galactose-α-1,3-galactose (alpha-gal). Tick saliva contains alpha-gal, and tick bites are considered a major cause of the induction of alpha-gal-sIgE. The origin of alpha-gal in tick saliva remains unclarified. The presence of alpha-gal in tick tissue was visualized in this study to provide an overview of the spatial distribution of alpha-gal and to further elucidate the origin of alpha-gal in tick saliva. Fed and unfed Ixodes ricinus females were examined by histology, immunohistochemistry, immunofluorescence, transmission electron microscopy and immunoelectron microscopy using the alpha-gal-specific monoclonal antibody M86 and Marasmius oreades agglutinin (MOA) lectin. Alpha-gal epitopes were detected in the midgut, hemolymph and salivary glands, and the immunofluorescence analysis revealed signs of the endocytosis of alpha-gal-containing constituents during the process of hematophagy. Alpha-gal epitopes in endosomes of the digestive gut cells of the ticks were observed via immunoelectron microscopy. Alpha-gal epitopes were detected in dried droplets of hemolymph from unfed ticks. Intense staining of alpha-gal epitopes was found in type II granular acini of the salivary glands of fed and unfed ticks. Our data suggest that alpha-gal is not ubiquitously expressed in tick tissue but is present in both fed and unfed ticks. The findings also indicate that both the metabolic incorporation of constituents from a mammalian blood meal and endogenous production contribute to the presence of alpha-gal epitopes in ticks.

Diagnosis & management of alpha-gal syndrome: lessons from 2,500 patients

INTRODUCTION

Alpha-gal Syndrome (AGS) is a unique allergy to non-primate mammalian meat (and derived-products) that is associated with tick bites and is due to a specific IgE antibody to the oligosaccharide galactose-α-1,3-galactose (alpha-gal). AGS has many novel features that broaden the paradigm of food allergy, including that reactions are delayed 3-6 hours after exposure and patients have frequently tolerated red meat for many years prior to the development of allergic reactions. Due to the ubiquitous inclusion of mammal-derived materials in foods, medications, personal products and stabilizing compounds, full avoidance is difficult to achieve.

AREAS COVERED

This review describes the author's experience with diagnosis, management, and design of appropriate avoidance for patients with AGS and provides clinicians with practical advice for care of these patients.

EXPERT OPINION

The number of patients with AGS is rising and may have exceeded awareness of the diagnosis amongst healthcare providers. In summarizing experience gained to thus far, we hope to create a resource for identifying and managing this unique allergic syndrome.

A BULL IN A PILL SHOP: ALPHA-GAL ALLERGY COMPLICATING TREATMENT OPTIONS FOR POSTPROCEDURAL HYPOTHYROIDISM

Objective

The galactose-alpha-1,3-galactose (alpha-gal) allergy, an IgE-mediated response to nonprimate meat, has a singular pathogenesis linked to tick bites and a delayed allergic presentation, which makes it especially cumbersome to diagnose and manage. As a large array of enteral medications contain ingredients derived from meat byproducts, this can affect the care of alpha-gal patients across multiple medical disciplines. Our objective is to present a patient with an alpha-gal allergy, which can complicate hypothyroidism treatment selection.

Methods

In this case of difficulty tailoring thyroid replacement therapy secondary to the alpha-gal allergy, the diagnostic studies included IgE immunoassays for alpha-gal as well as thyroid function tests.

Results

A 45-year-old woman with postoperative hypothyroidism and a history of an alpha-gal allergy (diagnosed after an anaphylactic reaction to beef) could not be immediately started on any common thyroid hormone replacement formulation because of our concern regarding the possible presence of nonprimate mammalian meat byproduct components in the thyroid hormone medication. After consulting allergy and immunology specialists and compounding pharmacists and contacting multiple drug companies in an effort to confirm the nature of the inactive ingredients in their thyroid hormone products, she was prescribed a plant-based compounded levothyroxine preparation with good clinical results.

Conclusion

This case emphasizes the importance of recognizing various risk factors and common drugs which may be associated with the alpha-gal allergy. It is not known how to best tailor enteral medications for patients with an alpha-gal allergy. Further research and pharmaceutical attention to this allergy are needed.

Comparative glycosylation mapping of plasma-derived and recombinant human factor VIII

Human coagulation factor VIII (FVIII) is a key co-factor in the clotting cascade, the deficiency of which leads to Hemophilia A. Human plasma-derived (pdFVIII) and recombinant FVIII (rFVIII) had been used as effective products to prevent and treat bleeding episodes. Both FVIII products share identical amino acid sequences and appear to be equivalent as of clinical efficiency. However, systemic reviews found an increased risk of neutralizing antibody (or inhibitor) development with recombinant products. FVIII is a highly glycosylated protein, and its glycosylation pattern is specific to host cells and environments. The roles of glycosylation in immune responses toward pdFVIII and rFVIII are yet to be defined. Herein, we systemically profiled N- and O-glycomes of pdFVIII and rFVIII using a mass spectrometry-based glycoproteomic strategy. A total of 110 site-specific N-glycopeptides consisting of 61 N-glycoforms were identified quantitatively from rFVIII and pdFVIII. Additionally, 31 O-glycoforms were identified on 23 peptides from rFVIII and pdFVIII. A comprehensive comparison of their site-specific glycan profiles revealed distinct differences between the glycosylation of pdFVIII and rFVIII.

Galactose-α-1,3-galactose (alpha-gal) allergy: first pediatric case in a series of patients in Spain

INTRODUCTION AND OBJECTIVES

Allergy to galactose-α-1,3-galactose (alpha-gal) is a peculiar form of food allergy generally manifesting as an anaphylactic reaction hours after mammalian meat consumption, due to the presence of specific IgE against this oligosaccharide. In addition, immediate anaphylaxis may develop after exposure to other sources of alpha-gal, such as monoclonal antibody cetuximab, vaccines, plasma expanders or anti-snake venoms. Sensitization to alpha-gal has also been implicated in the rapid degeneration of biological valve implants, and recognized as a cause of occupational disease in cattle raisers. The implication of tick bites in this type of sensitization has been accepted by all the research groups dedicated to this disease.

PATIENTS AND METHOD

The present study describes the clinical and sensitization characteristics of 39 patients diagnosed with alpha-gal allergy in the hospitals of our province (Lugo, Monforte de Lemos and Burela, Spain).

RESULTS

Most patients were middle-age males. Of note, is the fact that the series includes the first pediatric patient reported in Spain to date. The predominant clinical manifestations were urticaria or delayed anaphylaxis after consumption of mammalian meat. Seventy-four percent of the patients reported having suffered a previous tick bite, and the clinical presentation of anaphylaxis was significantly more prevalent in those with a persistent local reaction following the bite than in those with no such reaction (p = 0.032).

CONCLUSIONS

A review is also made of the disorder which, due to its variable clinical expression, is referred to as alpha-gal syndrome. The study concludes that a diagnosis of alpha-gal allergy should be considered in patients with urticaria-anaphylaxis of uncertain origin or manifesting after the administration of vaccines or products of bovine/porcine origin.

On the cause and consequences of IgE to galactose-α-1,3-galactose: A report from the National Institute of Allergy and Infectious Diseases Workshop on Understanding IgE-Mediated Mammalian Meat Allergy

The mammalian meat allergy known as the "α-Gal syndrome" relates to IgE specific for galactose-α-1,3-galactose (α-Gal), an oligosaccharide that is present in cells and tissues of nonprimate mammals. The recognition of delayed reactions to food derived from mammals in patients with IgE to α-Gal and also the association with tick bites have been increasing worldwide. In 2018, the National Institute of Allergy and Infectious Diseases, Division of Allergy, Immunology and Transplantation, sponsored a workshop on this emerging tick-related disease. International experts from the fields of tick biology, allergy, immunology, infectious disease, and dermatology discussed the current state of our understanding of this emerging medical condition. The participants provided suggestions for specific research priorities and for the development of resources to advance our knowledge of the mechanisms, diagnosis, management, and prevention of this allergic disease. This publication is a summary of the workshop and the panel's recommendations are presented herein.

Prevalence and Impact of Type I Sensitization to Alpha-Gal in Patients Consulting an Allergy Unit

BACKGROUND

Alpha-gal syndrome is a complex allergy with high clinical relevance regarding mammalian-derived food and drugs and is characterized by the presence of IgE antibodies directed at the carbohydrate galactose-α-1,3-galactose. As not all alpha-gal sIgE-positive individuals pre-sent clinical symptoms upon consumption of mammalian meat, the diagnostic value of alpha-gal sIgE has yet to be clarified.

OBJECTIVE

To investigate the prevalence of alpha-gal-sIgE positivity among allergy patients, examine the impact of tick bites as associated risk factors and determine the diagnostic value of alpha-gal-sIgE positivity.

METHODS

A retrospective cross-sectional study evaluating patients in the Allergy Unit was performed. Alpha-gal-sIgE levels were assessed by ImmunoCAP assay. Exposure to tick bites was assessed by a questionnaire. A receiver operating characteristics (ROC) curve analysis was performed to determine the diagnostic value of alpha-gal sIgE for the diagnosis of alpha-gal syndrome.

RESULTS

In the study population (n = 1369), the overall prevalence of alpha-gal-sIgE-positive (≥0.10 kUA/L) individuals was 19.9%, and the highest prevalence (30.2%) was found in patients with insect venom allergies. A reported tick bite within the 12 months prior to blood sampling significantly increased the risk of alpha-gal-sIgE positivity (OR 2.084). The ROC curve analysis indicated alpha-gal sIgE ≥0.54 kUA/L as the optimal cutoff point for assessing the diagnostic value of alpha-gal syndrome in allergy patients.

CONCLUSIONS

In allergy care settings, alpha-gal-sIgE positivity is a common finding. Alpha-gal sIgE is a sensitive marker in the diagnosis of alpha-gal syndrome but has limited predictive value for the characteristics or severity of this allergy.

Diagnosis and Management of Patients with the α-Gal Syndrome

The galactose-α-1,3-galactose (α-Gal) syndrome has many novel features that are relevant to diagnosis and management. In most cases, the diagnosis can be made on a history of delayed allergic reactions to mammalian meat and the blood test for IgE to the oligosaccharide α-Gal. In general, the diagnosis also dictates the primary treatment, that is, avoiding mammalian meat and also dairy in some cases. In the United States, the lone star tick is the primary cause of this disease, but different ticks are responsible in other countries. Blood levels of IgE to α-Gal often drop in patients who avoid recurrent tick bites, but the rate of decline is variable. Similarly, the delay before reactions is variable and the severity of the allergic reactions is not predicted by the delay or the titer of specific IgE. Some mammalian-derived products such as heart valves, gelatin-based plasma expanders, and pancreatic enzymes are relevant to only select patient groups. A minority of cases may benefit from avoiding a wide range of products that are prepared with mammalian-derived constituents, such as gelatin. This review focuses on the nature of the syndrome, common challenges in diagnosis and management, and also gaps in our current knowledge that would benefit from additional investigation.

[Diagnostics of alpha-gal syndrome : Current standards, pitfalls and perspectives]

α-Gal syndrome results from sensitization to the carbohydrate epitope galactose-α-1,3-galactose (α‑gal). The allergen occurs in mammalian meat and innards, but also in other foods and medical products of animal origin. Allergic reactions generally occur delayed after allergen intake with a latency period, depending on the individual tolerance threshold and the influence of cofactors. Details in the patient's medical history can help to establish the suspected diagnosis of α‑gal syndrome. Confirmation of the diagnosis requires the expertise of specialists, experienced with the implementation and interpretation of in vitro and in vivo diagnostic tests. Whereas skin prick testing with commercial whole-meat extracts often does not provide reliable results, allergen-specific IgE (α-gal) is generally detectable in affected patients. Cell-based tests such as the basophil activation test are currently only employed in an experimental setting. To evaluate, whether a sensitization is clinically relevant, an in-patient oral food challenge should be performed, using for example cooked pork or porcine kidney in addition to suspected cofactors.

Hazardous Medications in Children with Egg, Red Meat, Gelatin, Fish, and Cow's Milk Allergy

Childhood food allergies are a growing public health problem. Once the offending food allergens have been identified, a strict elimination diet is necessary in treatment or prevention of most of the allergic reactions. Accidental food ingestion can lead to severe anaphylaxis. Food- derived substances can be used in medications at various stages of the manufacturing process. In this review, the possible roles of medications which may contain egg, red meat, gelatin, and fish allergens on allergic reactions in children with food allergy were evaluated.

Tick-induced allergies: mammalian meat allergy and tick anaphylaxis

Mammalian meat allergy after tick bites and tick anaphylaxis are the most serious tick-induced allergies. They are often severe, should be largely avoidable and offer fascinating insights into the development and prevention of allergies. Australian clinicians reported the first cases of tick anaphylaxis and discovered the association between tick bites and the development of mammalian meat allergy. The subsequent finding of the allergen epitope within the meat responsible for the allergic reaction, α-gal (galactose-α-1,3-galactose), stimulated further interest in this emergent allergy. Reports of mammalian meat allergy associated with bites from several tick species have now come from every continent where humans are bitten by ticks. The number of diagnosed patients has continued to rise. Clinically, mammalian meat allergy and tick anaphylaxis present quite differently. The prominent role of cofactors in triggering episodes of mammalian meat allergy can make its diagnosis difficult. Management of mammalian meat allergy is complicated by the manifold potential therapeutic implications due to the widespread distribution of the mammalian meat allergen, α-gal. Exposures to α-gal-containing medications have proved lethal in a minority of people, and fatal tick anaphylaxis has been reported in Australia. Prevention of tick bites is prudent and practicable; killing the tick in situ is crucial to both primary and secondary prevention of allergic reactions. Mechanisms in the development of mammalian meat allergy constitute a paradigm for how allergies might arise.

Ingestion of mammalian meat and alpha-gal allergy: Clinical relevance in primary care

Background

An allergic reaction to mammalian meat has recently been reported in rural parts of South Africa and throughout other parts of the world. The cause of this allergic reaction is because of an oligosaccharide antigen known as galactose-alpha-1, 3-galactose (alpha-gal) found in mammalian meat. Hard ticks in various parts of the world have been identified as a cause of sensitisation to the alpha-gal antigen. However, mechanisms of sensitisation in Africa are poorly understood.

Aim

The aim of this article is to review current literature on the alpha-gal allergy and mammalian meat ingestion and the family physician’s role in diagnosing and managing this condition.

Method

Indexes were searched using the keywords in the following electronic databases: Elsevier Science Direct, Google Scholar, Medline and PubMed.

Results

Clinical presentation of the alpha-gal allergy occurs typically as a delayed anaphylaxis occurring within 3–6 hours after the ingestion of mammalian meat. A subset of patients described in South Africa presented with a rapid onset of symptoms occurring within 45 minutes. Furthermore, some of these patients present with abdominal symptoms only, which may be mistaken as food poisoning. Diagnosis is based on a history of reaction to mammalian meats (especially to fatty portions or organs) and serum specific alpha-gal antibodies. The main management of the alpha-gal allergy is avoidance of red meat and in mild reactions treatment with oral H1 receptor antihistamines.

Conclusion

Sensitisation to the alpha-gal allergy results in adverse reactions to red meat, with tolerance to turkey, chicken and fish. A family physician can safely manage this condition.

Keywords

alpha-gal allergy; mammalian meat; management; primary care; specific IgE antibody; alpha-gal sensitisation.

Galactose α-1,3-galactose phenotypes: Lessons from various patient populations

OBJECTIVE

To review published studies on galactose α-1,3-galactose (α-gal), a carbohydrate epitope found on proteins and lipids in nonprimate mammals and present in foods (particularly organ or fat-rich red meat) and medications, where it causes delayed-onset and immediate-onset anaphylaxis.

DATA SOURCES

A literature search for the terms galactose α-1,3-galactose and α-gal using PubMed and Embase was performed.

STUDY SELECTIONS

Studies on α-gal were included in this review.

RESULTS

Several species of ticks contain α-gal epitopes and possibly salivary adjuvants that promote high titer sensitization and clinical reactivity. Risk factors for α-gal syndrome include exposure to ticks of particular species. Age and sex differences seen in various cohorts possibly reflect the prevalence of these exposures that vary according to setting.

CONCLUSION

The reason and mechanisms for delayed onset of food-related anaphylaxis and the preponderance of abdominal reactions are not clear but may involve the kinetics of allergen digestion and processing or immunologic presentation via a different mechanism from usual immediate-type food allergy.

Role and Mechanism of Galactose-Alpha-1,3-Galactose in the Elicitation of Delayed Anaphylactic Reactions to Red Meat

Purpose of Review

The alpha-Gal (α-Gal) syndrome is characterized by the presence of IgE antibodies directed at the carbohydrate galactose-alpha-1,3-galactose (α-Gal). In this article, we review the presence of α-Gal in food and non-food sources; we discuss the evolutionary context of the antibody response to α-Gal and highlight immune responses to α-Gal and other carbohydrates.

Recent findings

IgE antibodies have been associated with delayed allergy to red meat. In addition to food, drugs, and other products of animal origin are increasingly perceived as a risk for patients sensitized to α-Gal. The link between tick bites and anti-α-Gal IgE-antibody production that has been established first by epidemiological studies has now been confirmed in mouse models.

Summary

The anti-α-Gal immune response is complex and characterized by a unique feature. IgM and IgG antibodies have been found to confer protection against pathogens whereas the IgE-response to α-Gal is detrimental and causes severe reactions upon exposure to mammalian meat and other products.

Highlights and recent developments in food and drug allergy, and anaphylaxis in EAACI Journals (2017)

This review highlights research advances and important achievements in food allergy, anaphylaxis, and drug allergy that were published in the Journals of the European Academy of Allergy and Clinical Immunology (EAACI) in 2017. Food allergy and anaphylaxis research have continued to rapidly accelerate, with increasing numbers of outstanding developments in 2017. We saw new studies on the mechanisms, diagnosis, prevention of food allergy, and novel food allergens. Drug hypersensitivity, as well as hereditary angioedema, has been highlighted in the present review as the focus of recent developments. The EAACI owns three journals: Allergy, Pediatric Allergy and Immunology (PAI), and Clinical and Translational Allergy (CTA). One of the major goals of the EAACI is to support health promotion in which prevention of allergy and asthma plays a critical role and to disseminate the knowledge of allergy to all stakeholders including the EAACI junior members. This paper summarizes the achievements of 2017 in anaphylaxis, and food and drug allergy.

Claire M, Janosko KB, Smith G, Glenn G, Hooper J, Dye J, Pal S, Bishop-Lilly KA, Hamilton T, Frey K, Bollinger L, Wada J, Wu H, Jiao JA, Olinger GG, Gunn B, Alter G, Khurana S, Hensley LE, Sullivan E, Jahrling PB. Fully Human Immunoglobulin G From Transchromosomic Bovines Treats Nonhuman Primates Infected With Ebola Virus Makona Isolate

Transchromosomic bovines (Tc-bovines) adaptively produce fully human polyclonal immunoglobulin (Ig)G antibodies after exposure to immunogenic antigen(s). The National Interagency Confederation for Biological Research and collaborators rapidly produced and then evaluated anti-Ebola virus IgG immunoglobulins (collectively termed SAB-139) purified from Tc-bovine plasma after sequential hyperimmunization with an Ebola virus Makona isolate glycoprotein nanoparticle vaccine. SAB-139 was characterized by several in vitro production, research, and clinical level assays using wild-type Makona-C05 or recombinant virus/antigens from different Ebola virus variants. SAB-139 potently activates natural killer cells, monocytes, and peripheral blood mononuclear cells and has high-binding avidity demonstrated by surface plasmon resonance. SAB-139 has similar concentrations of galactose-α-1,3-galactose carbohydrates compared with human-derived intravenous Ig, and the IgG1 subclass antibody is predominant. All rhesus macaques infected with Ebola virus/H.sapiens-tc/GIN/2014/Makona-C05 and treated with sufficient SAB-139 at 1 day (n = 6) or 3 days (n = 6) postinfection survived versus 0% of controls. This study demonstrates that Tc-bovines can produce pathogen-specific human Ig to prevent and/or treat patients when an emerging infectious disease either threatens to or becomes an epidemic.

The basophil activation test differentiates between patients with alpha-gal syndrome and asymptomatic alpha-gal sensitization

BACKGROUND

Galactose-alpha-1,3-galactose (alpha-gal) syndrome is characterized by the presence of serum specific IgE antibodies to alpha-gal and delayed type I allergic reactions to the carbohydrate alpha-gal after consumption of mammalian (red) meat products and drugs of mammalian origin. Diagnostics currently rely on patient history, skin tests, determination of serum specific IgE antibodies, and oral food or drug challenges.

OBJECTIVE

We sought to assess the utility of different basophil parameters (basophil reactivity and sensitivity, the ratio of the percentage of CD63⁺ basophils induced by the alpha-gal-containing allergen to the percentage of CD63⁺ basophils after stimulation with anti-FcεRI antibody [%CD63⁺/anti-FcεRI], and area under the dose-response curve [AUC]) as biomarkers for the clinical outcome of patients with alpha-gal syndrome compared with subjects with asymptomatic alpha-gal sensitization.

METHODS

In addition to routine diagnostics, a basophil activation test (Flow CAST) with different concentrations of alpha-gal-containing allergens (eg, commercially available alpha-gal-carrying proteins and pork kidney extracts) was performed in 21 patients with alpha-gal syndrome, 12 alpha-gal-sensitized subjects, and 18 control subjects.

RESULTS

Alpha-gal-containing allergens induced strong basophil activation in a dose-dependent manner in patients. Basophil reactivity at distinct allergen concentrations, the %CD63⁺/anti-FcεRI ratio across most allergen concentrations, the AUC of dose-response curves, and basophil allergen threshold sensitivity (CD-sens) with pork kidney extract were significantly higher in patients with alpha-gal syndrome compared with those in sensitized subjects. All parameters were negative in control subjects.

CONCLUSION

The basophil activation test should be considered as an additional diagnostic test before performing time-consuming and potentially risky oral provocation tests. The %CD63⁺/anti-FcεRI ratio for all allergens and AUCs for pork kidney were the best parameters for distinguishing patients with alpha-gal syndrome from subjects with asymptomatic alpha-gal sensitization.

Meat allergy and allergens

IgE-mediated hypersensitivity to ingested animal products, including both mammalian and avian sources, is increasingly appreciated as an important form of food allergy. Traditionally described largely in children, it is now clear that allergy to meat (and animal viscera) impacts both children and adults and represents a heterogeneous group of allergic disorders with multiple distinct syndromes. The recognition of entities such as pork-cat syndrome and delayed anaphylaxis to red meat, i.e- the α-Gal syndrome, have shed light on fundamental, and in some cases newly appreciated, features of allergic disease. These include insights into routes of exposure and mechanisms of sensitization, as well as the realization that IgE-mediated reactions can be delayed by several hours. Here we review mammalian and avian meat allergy with an emphasis on the molecular allergens and pathways that contribute to disease, as well as the role of in vitro IgE testing in diagnosis and management.

Prevalence of type I sensitization to alpha-gal in forest service employees and hunters

BACKGROUND

The production of IgE molecules specific to the carbohydrate galactose-α-1,3-galactose (alpha-gal) is known to induce delayed anaphylaxis against mammalian meat. Tick bites constitute the primary sensitization source, as ticks transfer alpha-gal in their saliva to a host during a bite. The reported prevalence of alpha-gal-specific IgE (alpha-gal-sIgE) positivity varies between different populations from diverse geographic regions.

OBJECTIVE

To investigate the prevalence of alpha-gal-sIgE positivity in a population of forest service employees who are highly exposed to ticks in comparison with a residential population and a historic sample.

METHODS

A cross-sectional study evaluating 300 forest service employees and hunters from southwest Germany was performed. Alpha-gal-sIgE levels were assessed by ImmunoCAP assay. The prevalence of alpha-gal-sIgE-positive individuals was compared with a matched cohort composed of a residential population and blood samples from forest service employees collected 15 years ago.

RESULTS

In the study population, the prevalence of alpha-gal-sIgE-positive (≥0.10 kU_A /L) individuals was 35.0%, whereas the prevalence of individuals with alpha-gal-sIgE levels ≥0.35 kU_A /L was 19.3%. Alpha-gal-sIgE positivity was associated with total IgE levels and recent tick bites. Mammalian meat-induced delayed anaphylaxis was found in 8.6% of the participants with alpha-gal-sIgE levels ≥0.35 kU_A /L. For forest service employees and hunters, the odds ratio for alpha-gal-sIgE positivity was 2.48 compared to the residential population. The prevalence of alpha-gal-sIgE positivity in the current and historic cohort was comparable.

CONCLUSION

Forest service employees and hunters compose a population with a high prevalence of alpha-gal-sIgE positivity and carry a considerable risk of red meat allergy.