Clinical Manifestations and Risk Factors of Anaphylaxis in Pollen-Food Allergy Syndrome

Revisiting Fruit Allergy: Prevalence across the Globe, Diagnosis, and Current Management

Fruit allergies manifest with a diverse array of clinical presentations, ranging from localized contact allergies and oral allergy syndrome to the potential for severe systemic reactions including anaphylaxis. The scope of population-level prevalence studies remains limited, largely derived from single-center or hospital-based investigations. In this comprehensive review, we conducted a systematic literature search spanning the years 2009 to 2023, with full acknowledgment of potential analytical biases, to provide a global overview of fruit allergy prevalence. The primary mechanistic underpinning of fruit allergies stems from cross-reactivity between aeroallergens and food allergens, a consequence of structurally similar epitopes-a phenomenon recognized as pollen food allergy syndrome (PFAS). In the era of molecular allergology, numerous studies have dissected allergen components with substantial clinical relevance. Within this review, we explore important allergenic molecules found in plant-based foods, scrutinize pertinent cross-reactivity patterns, and offer insights into management recommendations. Additionally, we compare guideline recommendations to enhance clinical understanding and inform decision making.

Fruitful or unfruitful: strawberry and tomato specific immunoglobulin E testing at a tertiary pediatric center

Background

Suspected strawberry and tomato (S/T) food allergy (FA) can be evaluated using specific immunoglobulin E (sIgE) testing despite its low specificity and positive predictive value.

Objective

This study aims to understand ordering patterns for S/T sIgE testing and identify relevant factors to clinical decision-making.

Methods

We retrospectively reviewed 814 patients with sIgE testing available for strawberries (651), tomatoes (276), or both (113) from January 2012 to May 2022 at a tertiary pediatric hospital. Patient demographics, provider specialty, and reasons for testing were collected. Student's t-test and multiple regression analyses were performed to test the association between the S/T sIgE level and clinically relevant outcome (CRO) status. Fisher's exact test and general linear models were used to evaluate and compare potential predictive factors for CRO status.

Results

Allergy and immunology, gastroenterology, and general pediatrics ordered most S/T sIgE testing. Testing was ordered most frequently for non-IgE-mediated gastrointestinal symptoms, mild possible IgE-mediated reactions, and eczema. Testing was most often ordered for infants and school-age children. Mean sIgE levels were higher for S/T tests resulting in a CRO when controlling for other predictor variables (p = 0.015; p = 0.002 for S/T, respectively). Only 2.2% and 5.4% of tests resulted in a CRO for S/T, and severe allergy was rare. Testing for non-IgE-mediated GI symptoms or eczema, or in non-atopic patients, yielded no CROs. Exposure and reaction history of present illness (ERH) was associated with CROs (p < 0.001; p = 0.04) with a high negative predictive value (99.5%; 100%) and low positive predictive value (11.5%; 15.0%). ERH (p < 0.001, η2 = 0.073; p = 0.009, η2 = 0.123) was a more significant predictor than the sIgE level (p = 0.002, η2 = 0.037; p = 0.212, η2 = 0.030) for CRO status.

Conclusion

The diagnosis of S/T food allergy is made primarily based on clinical history. S/T sIgE testing for children and adolescents should be avoided for patients without an ERH and in the workup of non-IgE-mediated GI symptoms. Testing for eczema and non-atopic patients is likely low-yield.

New arrivals in anaphylaxis to foods

PURPOSE OF REVIEW

More people are excluding wheat from their diet, or turning to a more sustainable diet in which includes meat substitutes or is mainly or wholly plant-based. This increases the availability of new foods and with it the increasing likelihood of novel allergens.

RECENT FINDINGS

There is a growing body of evidence which suggests that allergies to seeds and legumes are increasing potentially due to their use in concentrated form in vegan or health foods. Insects can be a sustainable source of protein, but mealworm could provoke symptoms in individuals sensitized or allergic to shellfish or house dust mite. Novel plant food allergens such as gibberellin-regulated proteins and thaumatin-like proteins are increasingly being reported as significant causes of severe reactions to fruits.

SUMMARY

these findings make it even more imperative to take a full dietary history to ensure apparent idiopathic anaphylaxis is not in reality due to a novel food, especially in cases where other forms of the food are tolerated. Given the lack of diagnostic tests for these novel foods, a prick-to-prick skin prick test should be performed with the suspected food. There is currently more work needed to define and sequence many of the allergens involved.

Anaphylaxis across Europe: are pollen food syndrome and lipid transfer protein allergy so far apart?

PURPOSE OF REVIEW

Traditionally pollen-food syndrome (PFS) is considered to be a mild cross-reacting food allergy affecting only Northern Europe, with lipid transfer protein (LTP) allergy being more severe and mainly occurring in Southern Europe. This review seeks to update the reader on both types of plant food allergy and to determine whether the stereotypical presentations of these plant food allergies remain the same, with a particular focus on reaction severity.

RECENT FINDINGS

Recent findings suggest that both these types of plant food allergy occur in children and adults. Although it is true that PFS allergy is more prevalent in Northern Europe and LTP allergy is more well known in Southern Europe, these conditions are not hidebound by geography, and the increasing spread and allergenicity of pollen due to global warming continues to change their presentation. Both conditions have a spectrum of symptom severity, with PFS sometimes presenting with more severe symptoms, including anaphylaxis and LTP allergy with milder reactions.

SUMMARY

It is important to consider that in many parts of Europe, reactions to plant foods, especially fruits or vegetables, could be mediated either by pollen cross-reactivity or primary sensitization to LTP allergens. All those presenting with symptoms to plant foods will benefit from a detailed clinical history and appropriate tests so that an accurate diagnosis can be made, and correct management implemented.

Real-life evaluation of molecular multiplex IgE test methods in the diagnosis of pollen associated food allergy

BACKGROUND

Diagnosis of food allergies is challenging, as combining information from specific IgE (sIgE)-sensitization pattern and skin prick tests (SPTs) with clinical history is necessary for a personalized management of allergic patients. The aim of this study was to compare two molecular tests, the ImmunoCAP ISAC (ISAC) and the Allergy Explorer, version 2 (ALEX² ) in the context of pollen food syndrome (PFS) diagnosis in a real-life scenario, to assess the benefit of multiplex testing in PFS patients.

METHODS

Diagnosis of food allergy was performed in 53 patients. Allergen-sIgE concentrations were measured with ISAC and ALEX² . Results for sIgE were statistically compared with each other, with SPT results and with clinical presentation of the patients.

RESULTS

Using ISAC as reference test for sIgE measurements, the average sensitivity of ALEX² for PR-10 allergens was 83.2% and the average specificity 88.0%. If only low sIgE concentrations were included, the sensitivity was 60.8% and the specificity 91.1%. Apple and hazelnut sensitizations were confirmed in most patients by concordance of sIgE and SPT results. Significant correlations were shown between clinical symptoms and Mal d 1- and Gly m 4-sIgE levels measured by both tests and for Cor a 1-sIgE levels measured by ALEX² . In eight patients, profilin related symptoms were supported by Hev b 8-sensitization.

CONCLUSION

Multiplex testing is beneficial to understand patient-specific individual sensitization profiles and to providing personalized management recommendations. In the future, custom-designed test kits might enable reducing costs of multiplex testing for specific patient groups without compromising the diagnostic value.

Development of mouse model for oral allergy syndrome to identify IgE cross-reactive pollen and food allergens: ragweed pollen cross-reacts with fennel and black pepper

Oral allergy syndrome (OAS) is an IgE-mediated immediate food allergy that is localized to the oral mucosa. Pollen food allergy syndrome (PFAS), a pollinosis-associated OAS, is caused by cross-reactivity between food and pollen allergens. However, we need to more precisely understand the underlying pathogenesis of OAS/PFAS. In the present study, we developed a method to comprehensively identify cross-reactive allergens by using murine model of OAS and protein microarray technology. We focused on lip angioedema, which is one of the most common symptoms of OAS, and confirmed that mast cells reside in the tissues inside the lower lip of the mice. Interestingly, when the food allergen ovalbumin (OVA) was injected inside the lower lip of mice with high levels of OVA-specific IgE followed by an intravenous injection of the Evans blue dye, we found immediate dye extravasation in the skin of the neck in a mast cell-dependent manner. In addition, the degree of mast cell degranulation in the oral cavity, reflecting the severity of oral allergic responses, can be estimated by measuring the amount of extravasated dye in the skin. Therefore, we used this model of OAS to examine IgE cross-reactive allergens in vivo. Protein microarray analysis showed that serum IgE from mice intraperitoneally sensitized with ragweed pollen, one of the major pollens causing pollinosis, bound highly to protein extracts from several edible plants including black peppercorn and fennel. We confirmed that the levels of black pepper-specific IgE and fennel-specific IgE were significantly higher in the serum from ragweed pollen-sensitized mice than in the serum from non-sensitized control mice. Importantly, analysis of murine model of OAS showed that the injection of black pepper or fennel extract induced apparent oral allergic responses in ragweed pollen-sensitized mice. These results indicate IgE cross-reactivity of ragweed pollen with black pepper and fennel. In conclusion, we developed mouse model of OAS to identify IgE cross-reactive pollen and food allergens, which will help understand the pathogenesis of OAS/PFAS.

Anaphylaxis in Chinese Children with Pollen Sensitization: Triggers, Clinical Presentation, and Acute Management

Purpose

Pollen sensitization is increasing in children. However, there is little evidence regarding the characteristics of anaphylaxis in individuals with pollen sensitization.

Patients and Methods

We conducted a retrospective study of patients with anaphylaxis combined with pollen sensitization who attended an allergy department in a tertiary children’s hospital from 2014 to 2021.

Results

A total of 157 anaphylaxis events in 108 patients were analyzed; the mean age at the reaction was 5.8 ± 4.17 years. A total of 99.1% (107/108) of the patients came from northern China. The most common sensitizing pollen was mugwort (93.5%,101/108), followed by ragweed (68.5%, 74/108) and birch (40.7%, 44/108). A total of 76.9% (83/108) of the patients showed polysensitization to pollen. Allergic rhinitis/conjunctivitis was the most common comorbidity (87.0%, 94/108). Children with severe anaphylaxis were more likely to have a history of recurrent urticaria (16.1% vs 3.9%, p = 0.028). The most frequently implicated foods were fruits/vegetables (22.3%, 35/157), followed by wheat (8.9%, 14/157) and milk (8.3%, 13/157), and the most common fruit allergen was peach (n = 7). Of 14% (22/157) exercise-induced reactions, 63.6% (14/22) occurred in pollen season. Skin symptoms were the most frequent (86.0%, 135/157) symptoms, followed by respiratory (73.9%, 116/157) and gastrointestinal (21%, 33/157) symptoms. Regarding acute management, only 7.4% of the patients were treated with epinephrine.

Conclusion

Our findings revealed the characteristics of anaphylaxis in children with pollen sensitization. Fruits/vegetables accounted for a substantial percentage of anaphylaxis triggers. The suboptimal use of epinephrine highlights the need for educational programs promoting the use of epinephrine.

A Pilot Study to Evaluate the Dietary Intake of Adults Attending a Food Allergy Clinic, and Compare the Results Against the Final Diagnostic Outcome

Background: The impact of poor diet on growth and development in children with a food allergy is well-recognized and researched. Food allergy is an increasing problem in adults, as are food intolerances. Another issue is the rising number of individuals adopting a vegetarian or vegan lifestyle. Studies evaluating the diet of adolescents and adults with food allergy against controls suggest their dietary intakes are similar. We wished to evaluate all patients attending a food allergy clinic to determine whether there were dietary and nutritional differences between those with a food allergy or a food intolerance. Methods: All adults newly referred to a secondary care food allergy clinic in a UK hospital, in a 1-month period, were included in the study. Prior to their appointment, those who consented to take part had their height and weight documented and an assessment made of their habitual food intake. Their subsequent diagnosis was reviewed, and results for those with a confirmed diagnosis of food allergy were compared to those with a food intolerance or where the cause of symptoms was unknown. Results: Thirty subjects were recruited, with full results available for 29 subjects, 15 of whom (52%) were diagnosed with a new/existing food allergy (FA). For the whole cohort, dietary intake was sufficient for protein, and most vitamins and minerals, whereas energy, carbohydrate, unsaturated fat and fiber intakes were well-below the reference range. Those with a FA had lower intakes of iron, zinc and vitamin B12 compared to those with no FA. In addition, iron and energy intakes were depleted in those avoiding nuts, and wheat avoidance was linked to a lower intake of riboflavin. Conclusion: The results from this small exploratory study suggest that whilst the majority of nutrients in the diet are sufficient in adults presenting to the food allergy clinic, intakes of energy and fiber may be below the reference range. Those with a food allergy are more likely to have a reduced intake of iron, zinc and vitamin B12. As others have demonstrated, the exclusion of specific food groups can also affect nutritional intakes.

Itch Beyond the Skin-Mucosal Itch

Itch is a nociceptive sensation linked with reflexes and cognitive motor actions. We traditionally think of itch as a sensation of the skin related to allergy, an insect sting or interestingly, anxiety and frustration. Less understood and considered are the physiological processes involved in the itching sensation that occurs at mucosal and junctional dermal sites, which is extraordinary as from an evolutionary point of view these sites serve important guardian roles, rich in sensory nerves and inflammatory cells. Despite itch being an ancient reflex and evolutionarily conserved phenomenon, better clinical understanding of the nuances between sites of itch sensation may lead to improved clinical outcomes. This review invites readers to appreciate itch beyond the skin by highlighting several specific itch patterns-nasal, oral, auricular, vulvovaginal, anal, and perineal itch-the pathophysiological mechanisms that underlie them, the clinical patterns these may cause, and some unique treatments.

Rosaceae food allergy: a review

This review provides a global overview on Rosaceae allergy and details the particularities of each fruit allergy induced by ten Rosaceae species: almond/peach/cherry/apricot/plum (Amygdaleae), apple/pear (Maleae), and raspberry/blackberry/strawberry (Rosoideae). Data on clinical symptoms, prevalence, diagnosis, and immunotherapies for the treatment of Rosaceae allergy are herein stated. Allergen molecular characterization, cross-reactivity/co-sensitization phenomena, the impact of food processing and digestibility, and the methods currently available for the Rosaceae detection/quantification in foods are also described. Rosaceae allergy has a major impact in context to pollen-food allergy syndrome (PFAS) and lipid transfer protein (LTP) allergies, being greatly influenced by geography, environment, and presence of cofactors. Peach, apple, and almond allergies are probably the ones most affecting the quality of life of the allergic-patients, although allergies to other Rosaceae fruits cannot be overlooked. From patients' perspective, self-allergy management and an efficient avoidance of multiple fruits are often difficult to achieve, which might raise the risk for cross-reactivity and co-sensitization phenomena and increase the severity of the induced allergic responses with time. At this point, the absence of effective allergy diagnosis (lack of specific molecular markers) and studies advancing potential immunotherapies are some gaps that certainly will prompt the progress on novel strategies to manage Rosaceae food allergies.

Phenotypes and Endotypes of Peach Allergy: What Is New?

Peach allergy is emerging as a common type of fresh-fruit allergy in Europe, especially in the Mediterranean area. The clinical manifestations of peach allergy tend to have a peculiar geographical distribution and can range from mild oral symptoms to anaphylaxis, depending on the allergic sensitization profile. The peach allergen Pru p 7, also known as peamaclein, has recently been identified as a marker of peach allergy severity and as being responsible for peculiar clinical features in areas with high exposure to cypress pollen. This review addresses the latest findings on molecular allergens for the diagnosis of peach allergy, the clinical phenotypes and endotypes of peach allergy in adults and children, and management strategies, including immunotherapy, for peach allergy.

Surveillance of pollen-food allergy syndrome in elementary and junior high school children in Saitama, Japan

Background

Because few studies have epidemiologically evaluated pollen-food allergy syndrome (PFAS), relevant information about this disease is limited in children.

Objective

We wanted to clarify the epidemiological details of PFAS by creating a questionnaire which enables to distinguish class 2 food allergy from that of class 1.

Methods

We conducted a questionnaire survey for schoolchildren attending to public elementary and junior high schools. In this questionnaire, we asked about both the allergy to fruits and/or vegetables and allergic rhinitis (AR). PFAS was, then, defined as allergy for fruits and/or vegetable which occurred after the symptoms of AR appeared.

Results

A total of 2,346 children (median age, 10.6±2.5 years; 1,157 boys) were evaluated. The prevalence of PFAS was 6.9% among subjects. The mean ages in the onset of AR and PFAS were 4.59±2.76 and 7.38±3.17 years old, respectively. Various kinds of foods were shown to be causative, among which kiwifruits were the commonest. As high as approximately 30% of children with PFAS experienced systemic symptoms including cutaneous (21.8%) and respiratory symptoms (9.6%). Anaphylaxis was diagnosed in 5.8% children.

Conclusion

Our results indicated that the prevalence of PFAS was getting higher and the mean age of onset was getting lower. These may be attributed to the increasing number of patients with AR and also to the lower age of onset of AR. We have to be careful to not only local but also systemic symptoms when examining children with PFAS.

Analysis of Peanut Allergen Components Sensitization and Cross Reaction with Pollen Allergen in Chinese Southerners with Allergic Rhinitis and/or Asthma

Objective

Peanut is one of the most frequently reported allergens causing severe allergies in western countries. In China, however, there have been few reports of severe allergies caused by peanuts. We investigated the peanut allergen components sensitization and cross-reaction with pollen allergen in Chinese Southerners with allergic rhinitis and/or asthma.

Methods

Total IgE (tIgE) and specific IgE (sIgE) antibodies against Ara h 1, Ara h 8, Juglans pollen, Platanus pollen, birch pollen, Bet v 1, Bet v 4, and cross-reactive carbohydrate determinant (CCD) of 58 allergic patients, of whom 33 were peanut-sIgE positive and 25 were negative, were detected by the ImmunoCAP system. The relationships between peanut allergen and pollen allergens were analyzed.

Results

A 9.1% (3/33) of the patients with peanut sensitization were sensitized to Ara h 8, while 21.2% (7/33) were sensitized to Ara h 1. The peanut-sensitized group had significantly higher positive rates for sIgE antibodies against CCD (69.7% vs 4.0%), Juglans pollen (87.9% vs 12.0%), Platanus pollen (90.9% vs 16.0%), and birch pollen (60.6% vs 4.0%) than the peanut tolerance group (all P < 0.05). Spearman correlation showed that peanut-sIgE were significantly correlated with sIgE to CCD (r_s=0.859), Juglans pollen (r_s=0.772), Platanus pollen (r_s=0.838) and birch pollen (r_s=0.816).

Conclusion

The majority of patients sensitized to peanut allergen in Southern China tested positive for multiple pollen allergens. Peanut sensitization was highly correlated with Platanus, Juglans, and birch pollen sensitization, which suggested there may be cross-reactions between peanut and pollen allergens. Clinicians should pay attention to distinguish diagnosis in clinical peanut allergy diagnosis and treatment.

Heterogeneity of pollen food allergy syndrome in seven Southern European countries: The @IT.2020 multicenter study

BACKGROUND

Pollen food allergy syndrome (PFAS) is a frequently underdiagnosed disease due to diverse triggers, clinical presentations, and test results. This is especially relevant in geographic areas with a broad spectrum of pollen sensitization, such as Southern Europe.

OBJECTIVES

To elucidate similarities and differences of PFAS in nine Southern European centers and identify associated characteristics and unique markers of PFAS.

METHODS

As part of the @IT.2020 Multicenter Study, 815 patients with seasonal allergic rhinitis (SAR), aged 10-60 years, were recruited in seven countries. They completed questionnaires regarding SAR, comorbidities, family history, and PFAS, and underwent skin prick testing (SPT) and serum IgE testing.

RESULTS

Of the 815 patients, 167 (20.5%) reported PFAS reactions. Most commonly, eliciting foods were kiwi (58, 34.7%), peach (43, 25.7%), and melon (26, 15.6%). Reported reactions were mostly local (216/319, 67.7%), occurring within 5 min of contact with elicitors (209/319, 65.5%). Associated characteristics included positive IgE to at least one panallergen (profilin, PR-10, or nsLTP) (p = 0.007), maternal PFAS (OR: 3.716, p = 0.026), and asthma (OR: 1.752, p = 0.073). Between centers, heterogeneity in prevalence (Marseille: 7.5% vs. Rome: 41.4%, p < 0.001) and of clinical characteristics was apparent. Cypress played a limited role, with only 1/22 SPT mono-sensitized patients reporting a food reaction (p < 0.073).

CONCLUSIONS

PFAS is a frequent comorbidity in Southern European SAR patients. Significant heterogeneity of clinical characteristics in PFAS patients among the centers was observed and may be related to the different pollen sensitization patterns in each geographic area. IgE to panallergen(s), maternal PFAS, and asthma could be PFAS-associated characteristics.

From Allergen Molecules to Molecular Immunotherapy of Nut Allergy: A Hard Nut to Crack

Peanuts and tree nuts are two of the most common elicitors of immunoglobulin E (IgE)-mediated food allergy. Nut allergy is frequently associated with systemic reactions and can lead to potentially life-threatening respiratory and circulatory symptoms. Furthermore, nut allergy usually persists throughout life. Whether sensitized patients exhibit severe and life-threatening reactions (e.g., anaphylaxis), mild and/or local reactions (e.g., pollen-food allergy syndrome) or no relevant symptoms depends much on IgE recognition of digestion-resistant class I food allergens, IgE cross-reactivity of class II food allergens with respiratory allergens and clinically not relevant plant-derived carbohydrate epitopes, respectively. Accordingly, molecular allergy diagnosis based on the measurement of allergen-specific IgE levels to allergen molecules provides important information in addition to provocation testing in the diagnosis of food allergy. Molecular allergy diagnosis helps identifying the genuinely sensitizing nuts, it determines IgE sensitization to class I and II food allergen molecules and hence provides a basis for personalized forms of treatment such as precise prescription of diet and allergen-specific immunotherapy (AIT). Currently available forms of nut-specific AIT are based only on allergen extracts, have been mainly developed for peanut but not for other nuts and, unlike AIT for respiratory allergies which utilize often subcutaneous administration, are given preferentially by the oral route. Here we review prevalence of allergy to peanut and tree nuts in different populations of the world, summarize knowledge regarding the involved nut allergen molecules and current AIT approaches for nut allergy. We argue that nut-specific AIT may benefit from molecular subcutaneous AIT (SCIT) approaches but identify also possible hurdles for such an approach and explain why molecular SCIT may be a hard nut to crack.

Update on pollen-food allergy syndrome

INTRODUCTION

Allergies affect 20-30% of the population and respiratory allergies are mostly due to pollen grains from anemophilous plants. One to 5% of people suffer from food allergies and clinicians report increasing numbers of pollen-food allergy syndrome (PFAS), such that the symptoms have broadened from respiratory to gastrointestinal, and even to anaphylactic shock in the presence of cofactors. Thirty to 60% of food allergies are associated with pollen allergy while the percentage of pollen allergies associated to food allergy varies according to local environment and dietary habits.

AREAS COVERED

Articles published in peer-reviewed journals, covered by PubMed databank, clinical data are discussed including symptoms, diagnosis, and management. A chapter emphasizes the role of six well-known allergen families involved in PFAS: PR10 proteins, profilins, lipid transfer proteins, thaumatin-like proteins, isoflavone reductases, and β-1,3 glucanases. The relevance in PFAS of three supplementary allergen families is presented: oleosins, polygalacturonases, and gibberellin-regulated proteins. To support the discussion a few original relevant results were added.

EXPERT OPINION

Both allergenic sources, pollen and food, are submitted to the same stressful environmental changes resulting in an increase of pathogenesis-related proteins in which numerous allergens are found. This might be responsible for the potential increase of PFAS.

Can patients with oral allergy syndrome be at risk of anaphylaxis?

PURPOSE OF REVIEW

Oral allergy syndrome, also known as pollen-food syndrome (PFS), is a condition usually associated with adults and characterized by mild transient oropharyngeal symptoms. The purpose of this review is to determine whether systemic or anaphylactic reactions do occur and if so, who is affected and what are the triggers.

RECENT FINDINGS

An increasing number of studies demonstrate that PFS occurs all age groups, and a significant number of affected adults do experience systemic and anaphylactic reactions. The upsurge in the adoption of vegan lifestyles, increase in consumption of fruits and vegetables including smoothies and juices, and use of plant foods in nutritional or body-building supplements, could exacerbate this. Changes in pollen and pollution levels, cofactors and sensitization to other plant food allergens may also be involved.

SUMMARY

While the majority of those with PFS will continue to experience mild symptoms, all individuals should be properly advised regarding the dangers of concentrated or unusual forms of plant food allergens such as smoothies, juices, soy/nut milks and nutritional supplements. Further well characterized studies are needed to determine risk factors for severe reactions, and sensitization patterns to pollens and plant food allergens.

Sensitization profile to sawtooth oak component allergens and their clinical implications

OBJECTIVE

The component allergens from sawtooth oak, which is a main cause of tree pollinosis in Korea, have not been extensively characterized except Que ac 1. This study was undertaken to characterize the allergenic components from sawtooth oak pollen and investigate the diagnostic values of each component allergen.

METHODS

Transcriptomic analysis was performed to identify the birch pollen allergen homologues from sawtooth oak pollen. Recombinant Que ac 1, 2, 3, 6, 7, and 8 were produced in an E. coli expression system. IgE reactivity to each allergen was examined by ImmunoCAP and ELISA using the sera of 50 Korean tree pollinosis patients.

RESULTS

Six birch pollen allergen homologues were identified using transcriptome analysis, as follows: Que ac 1 (54.8% identity to Bet v 1), Que ac 2 (79.7% to Bet v 2), Que ac 3 (24.9% to Bet v 3), 6 (71.3% to Bet v 6), Que ac 7 (80.9% to Bet v 7), and Que ac 8 (78.9% to Bet v 8). Que ac 1 sIgE was the most frequently recognized (84.0%), followed by Que ac 2 (12.0%), Que ac 3 (6.0%), and three other allergens (2.0% each). Que ac 1 was a dominant allergen affecting 83.7% of patients suffering from allergic rhinoconjunctivitis, and 92.9% of pollen food allergy syndrome patients.

CONCLUSION

Five novel IgE reactive components of sawtooth oak were characterized using transcriptome analysis. Que ac 1 is the single most important component allergen of sawtooth oak pollen.

Fruit-Induced Anaphylaxis: Clinical Presentation and Management

BACKGROUND

Data are sparse regarding the clinical characteristics and management of fruit-induced anaphylaxis.

OBJECTIVE

To assess clinical characteristics and management of patients with fruit-induced anaphylaxis and determine factors associated with severe reactions and epinephrine use.

METHODS

Over 9 years, children and adults presenting with anaphylaxis to seven emergency departments in four Canadian provinces and patients requiring emergency medical services in Outaouais, Quebec were recruited as part of the Cross-Canada Anaphylaxis Registry. A standardized form documenting symptoms, triggers, and management was collected. Multivariate logistic regression was used to identify factors associated with severe reactions and epinephrine treatment in the pre-hospital setting.

RESULTS

We recruited 250 patients with fruit-induced anaphylaxis, median age 10.2 years (interquartile range, 3.6-23.4 years); 48.8% were male. The most common fruit triggers were kiwi (15.6%), banana (10.8%), and mango (9.2%). Twenty-three patients reported having eczema (9.3%). Epinephrine use was low in both the pre-hospital setting and the emergency department (28.4% and 40.8%, respectively). Severe reactions to fruit were more likely to occur in spring and among those with eczema (adjusted odds ratio [aOR] = 1.12, 95% confidence interval [CI], 1.03-1.23; and 1.17, 95% CI, 1.03-1.34, respectively). Patients with moderate and severe reactions (aOR = 1.23; 95% CI, 1.06-1.43) and those with a known food allergy (aOR = 1.38; 95% CI, 1.24-1.54) were more likely to be treated with epinephrine in the pre-hospital setting.

CONCLUSIONS

Severe anaphylaxis to fruit is more frequent in spring. Cross-reactivity to pollens is a potential explanation that should be evaluated further.

Allergens of Regional Importance in Korea

Allergen repertoire should reflect the region's climate, flora, and dining culture to allow for a better diagnosis. In Korea, tree pollens of oak and birch in the spring in conjunction with weed pollens of mugwort, ragweed, and Japanese hop are the main causes of seasonal allergic rhinitis. More specifically, the sawtooth oak in Korea and the Japanese hop in East Asia make a difference from western countries. Among food allergens, the sensitization to silkworm pupa and buckwheat is also common in Korean patients. Honey bee venom due to apitherapy in traditional medicine and Asian needle ant, Pachycondyla chinensis, are important causes of anaphylaxis in Korea. Climate change, frequent overseas traveling, and international product exchanges make situations more complicated. Ragweed, for example, was not native to Korea, but invaded the country in the early 1950s. Recently, Japanese hop and Asian needle ants have been recognized as important invasive ecosystem disturbing species in western countries. However, the molecular properties of the component allergens from these unique culprit allergens have been poorly characterized. The present review summarizes the molecular studies on the allergens of regional importance in Korea.

Validation of a Multiplex Assay for Measuring Specific IgG4

PURPOSE

Specific IgG4 (sIgG4) increases with allergen specific immunotherapy and may reflect a state of immune tolerance in food allergy. While ImmunoCAP® has been widely used to measure sIgG4 to a single allergen, PROTIA™ Specific IgG4® has been designed as a multiplex assay for measuring sIgG4. This study sought to validate this assay in comparison to ImmunoCAP®.

MATERIALS AND METHODS

Measurements of sIgG4 were compared between PROTIA™ Specific IgG4® and ImmunoCAP® using sera from 519 allergy patients (asthma: 114, allergic rhinitis: 318, food allergy: 146) with 731 paired tests. sIgG4 was measured against nine inhalant allergens (Dermatophagoides pteronyssinus, Dermatophagoides farinae, cat dander, dog dander, birch pollen, oak pollen, ragweed pollen, mugwort pollen, and Alternaria alternata spores) and nine food allergens (egg white, casein, wheat, peanut, walnut, crab, shrimp, apple, and peach).

RESULTS

PROTIA™ Specific IgG4® showed 95.6% agreement rate with ImmunoCAP® in the positivity comparison. For sIgG4 positivity to each individual allergen, an agreement rate of more than 84.8% was observed. In Cohen's kappa analysis, these assays displayed substantial correlations [Cohen's kappa coefficient (κ) ≥0.699], except for shrimp (κ=0.448). Furthermore, both assays displayed strong correlations in quantitative comparisons [correlation coefficients value (ρ) ≥0.8014], except for apple (ρ=0.6571, p=0.175). Serial dilution tests also showed consistency between the assays.

CONCLUSION

PROTIA™ Specific IgG4® showed high consistency with ImmunoCAP® in measuring sIgG4. This assay is applicable to various clinical fields, including allergen immunotherapy and food allergy.