Studying specific IgE: in vivo or in vitro

Gastropod Allergy: A Comprehensive Narrative Review

Food allergies have increased significantly in recent decades, with shellfish being a leading cause of food allergy and anaphylaxis worldwide, affecting both children and adults. The prevalence of shellfish allergies is estimated to be approximately 0.5-2.5% of the general population, varying significantly by geographical location, age, and consumption habits. Although mollusk consumption has risen, the prevalence of mollusk allergies remains unknown. While extensive research has focused on crustacean allergies, mollusk allergies, particularly those related to gastropods, have received comparatively less attention. Clinical manifestations of shellfish allergy range from localized symptoms to life-threatening systemic reactions, such as anaphylaxis. Notably, severe bronchospasm is a predominant clinical feature in cases involving gastropods. Several allergens have been identified in mollusks, including paramyosin, tropomyosin, and sarcoplasmic calcium-binding protein. In gastropods, documented allergens include tropomyosin, paramyosin, the heavy chain of myosin, and Der p 4 amylase. Diagnosis typically involves a thorough clinical history, skin testing, in vitro quantification of immunoglobulin (Ig) E, and confirmation through an oral challenge, although the latter is reserved for selected cases. This narrative review highlights the limited research on gastropod allergy. It provides a comprehensive list of purified and recombinant allergens and discusses the applications of component-resolved diagnosis as well as current therapeutic developments.

[RAST, Inmunoblot, Immunocap and ISAC in food allergy]

skin tests; Sensitization; IgE-mediated allergy; allergenic extract. After the discovery of IgE, technological advances have provided new laboratory tools for the quantification of allergen-specific IgE antibodies in serum and on the surface of basophils-mast cells. In vitro testing offers numerous advantages: accurate quantitation, lack of drug interference, safety, and long-term storage of samples. Quantitative immunoassays for IgE antibodies can be an adjunct to skin testing. The allergen reagent in solid phase (allergosorbent) or liquid is the main component of the assay that confers specificity to the IgE antibody test. It is the most complex and highly variable reagent in IgE antibody assays. The choice to use diagnostic recombinants on a single rather than multiple platforms is made on a case-by-case basis (considering prior history and clinical profile) and in an allergen-dependent manner. Although most food allergies are limited to a small number of possible triggers, these foods are very complex when evaluating their allergenic potential. The possibility of fractionating the allergen and understanding some of its components as potentially important to define the risk of clinical reaction, cross-reactivity, or persistence of allergy, opened a new era in the field of allergy, called molecular allergy. The identification of the allergenic component responsible for the reactions is an important tool to confirm the information and severity of the symptoms, natural history of the disease, possibility of cross-reactivity and clinical symptoms (allergy markers).

Retrospective Analysis of Allergen Distribution Dynamics in Central Taiwan

Introduction: Allergy is a type Ⅰ hypersensitivity reaction to certain substances (allergens) such as environmental factors, food and drugs. Allergies are a significant public health issue, and therefore, understanding the distribution patterns of allergens in specific regions is important. This study aimed to retrospectively analyse allergen distribution patterns in Central Taiwan over a 5 years period (2018-2022). Methods: Data of patients who had allergen sensitization testing using the OPTIGEN® Allergen-Specific IgE Assay from the 1st of January 2018 to the 31st of December 2022 were reviewed retrospectively. Statistical analyses were performed to determine the prevalence and distribution of allergens in our study population. Results: A total of 8,444 patients (3,784 males and 4,660 females) who attended the Asia University Hospital for allergen detection were enrolled in this study. Dermatophagoides farina (41.8%), Dermatophagoides pteronyssinus (37.9%), house dust (24.6%), cockroach mix (17.7%), crab (12.6%), clam (9.8%), shrimp (9.1%), cat dander (8.1%), pig weed (8%) and peanut (7.8%) were identified as the ten allergens that most commonly induced sensitization in our study population. Additionally, crab, clam, shrimp, peanut and beef were the five most common food allergens. Conclusion: In summary, our findings contribute significantly to the knowledge on allergen distribution in Central Taiwan. Our identification of prevalent allergens may contribute to an improved understanding of the epidemiology of allergies in this region.

Basophil Activation Test Utility as a Diagnostic Tool in LTP Allergy

Plant-food allergy is an increasing problem, with nonspecific lipid transfer proteins (nsLTPs) triggering mild/severe reactions. Pru p 3 is the major sensitizer in LTP food allergy (FA). However, in vivo and in vitro diagnosis is hampered by the need for differentiating between asymptomatic sensitization and allergy with clinical relevance. The basophil activation test (BAT) is an ex vivo method able to identify specific IgE related to the allergic response. Thus, we aimed to establish the value of BAT in a precise diagnosis of LTP-allergic patients. Ninety-two individuals with peach allergy sensitized to LTP, Pru p 3, were finally included, and 40.2% of them had symptoms to peanut (n = 37). In addition, 16 healthy subjects were recruited. BAT was performed with Pru p 3 and Ara h 9 (peanut LTP) at seven ten-fold concentrations, and was evaluated by flow cytometry, measuring the percentage of CD63 (%CD63+) and CD203c (%CD203chigh) cells, basophil allergen threshold sensitivity (CD-Sens), and area under the dose−response curve (AUC). Significant changes in BAT parameters (%CD63+ and %CD203chigh) were found between the controls and patients. However, comparisons for %CD63+, %CD203chigh, AUC, and CD-Sens showed similar levels among patients with different symptoms. An optimal cut-off was established from ROC curves, showing a significant positive percentage of BAT in patients compared to controls and great values of sensitivity (>87.5%) and specificity (>85%). In addition, BAT showed differences in LTP-allergic patients tolerant to peanut using its corresponding LTP, Ara h 9. BAT can be used as a potential diagnostic tool for identifying LTP allergy and for differentiating peanut tolerance, although neither reactivity nor sensitivity can distinguish the severity of the clinical symptoms.

Accuracy of immunoblotting assay for detection of specific IgE compared with ImmunoCAP in allergic patients

Background and aim

Standardized techniques help us to better diagnosis and follow up of allergic diseases. In this study, we determined the sensitivity, accuracy, and specificity of an Immunoblotting test compared to ImmunoCAP as the reference in vitro test for detection of specific IgE in allergic patients.

Methods

In this cross-sectional study, specific IgE level was determined in patients with allergic symptoms who referred to the Immunology, Asthma and Allergy Research Institute, Tehran, Iran from 2010–2016, by two techniques. Eleven different allergens (six aeroallergens and five food allergens) were determined, and 303 specific IgE tests were performed for the patients by each method. The Immunoblotting test is a multiplex assay on a nitrocellulose membrane coated with 20 selected allergens. ImmunoCAP is considered as the reference method for determination of in vitro specific IgE. Its principle is an automated sandwich immunoassay, and allergens were bound to the solid phase, covalently. Finally, the fluorescence of elute was determined. Specific IgE more than 0.35 KU/L was considered as a positive test. Sensitivity, specificity, accuracy, kappa coefficient, positive and negative likelihood ratio (+/− LR), and correlation coefficient (calculated with Spearman test) between two tests were determined using statistical analysis (SPSS software, version 18).

Results

One hundred and thirty five patients entered this study. The median age of the patients was 3.75 years with the males constituting 54.8% of the population. The most common cheif complaints were respiratory (51.6%), skin (41.8%) and gastrointestinal (27.9%) symptoms, respectively. The sensitivity, specificity, accuracy, +LR and −LR were 83%, 97%, 92%, 27.66 and 0.17, respectively. The kappa coefficient of the immunoblotting test was 0.81 compared to the reference technique. The correlation coefficient for positive tests between the two methods was 0.71 (p<0.001).

Conclusion

Regarding the presence of 20 allergens in a RIDA allergy panel and according to our findings, this immunoblotting test with high sensitivity could be used as a fast and cost-efficient screening test. However, ImmunoCAP is recommended when the accurate level of specific IgE is required. ImmunoCAP findings are particularly helpful for immunotherapy and the elimination diet.

Do immunoglobulin G and immunoglobulin E anti-l-asparaginase antibodies have distinct implications in children with acute lymphoblastic leukemia? A cross-sectional study

Background

l-Asparaginase is essential in the treatment of childhood acute lymphoblastic leukemia. If immunoglobulin G anti-l-asparaginase antibodies develop, they can lead to faster plasma clearance and reduced efficiency as well as to hypersensitivity reactions, in which immunoglobulin E can also participate. This study investigated the presence of immunoglobulin G and immunoglobulin E anti-l-asparaginase antibodies and their clinical associations.

Methods

Under 16-year-old patients at diagnosis of B-cell acute lymphoblastic leukemia confirmed by flow cytometry and treated with a uniform l-asparaginase and chemotherapy protocol were studied. Immunoglobulin G anti-l-asparaginase antibodies were measured using an enzyme-linked immunosorbent assay. Intradermal and prick skin testing was performed to establish the presence of specific immunoglobulin E anti-l-asparaginase antibodies in vivo. Statistical analysis was used to investigate associations of these antibodies with relevant clinical events and outcomes.

Results

Fifty-one children were studied with 42 (82.35%) having anti-l-asparaginase antibodies. In this group immunoglobulin G antibodies alone were documented in 10 (23.8%) compared to immunoglobulin E alone in 18 (42.8%) patients. Immunoglobulin G together with immunoglobulin E were simultaneously present in 14 patients. Children who produced exclusively immunoglobulin G or no antibodies had a lower event-free survival (p-value = 0.024). Eighteen children (35.3%) relapsed with five of nine of this group who had negative skin tests suffering additional relapses (range: 2–4), compared to none of the nine children who relapsed who had positive skin tests (p-value < 0.001).

Conclusion

Children with acute lymphoblastic leukemia and isolated immunoglobulin G anti-l-asparaginase antibodies had a higher relapse rate, whereas no additional relapses developed in children with immunoglobulin E anti-l-asparaginase antibodies after the first relapse.

Molecular-based diagnosis of respiratory allergic diseases in children from Curitiba, a city in Southern Brazil

BACKGROUND

Prevalence of respiratory allergic diseases has increased worldwide. Identification of the aeroallergens involved in allergenic sensitisation is important for diagnosis, treatment and prevention.

OBJECTIVE

To verify the molecular pattern of sensitisation to aeroallergens in patients with allergic respiratory diseases using microarray technique for specific IgE antibody detection.

METHODS

Cross-sectional study of 101 children with allergic rhinitis was followed in an outpatient clinic. All patients had positive skin prick tests (SPT) to at least one of the following antigens: Dermatophagoides pteronyssinus, Blomia tropicalis, Blattella germanica, Lolium multiflorum, and dog and cat epithelium. Serum specific IgE antibodies (sIgE) to mites, animal epithelia, fungi, cockroach and pollens components were determined by ImmunoCAP ISAC.

RESULTS

sIgE to group 1 and 2 mite allergens showed higher positive rates: Der p 1 (74.2%), Der p 2 (73.3%), Der f 1 (74.2%), Der f 2 (72.3%). sIgE to animal epithelia were less frequent, Can f 1, Can f 2, Can f 3 in 4.9%, 2.9%, 1.9% respectively and Fel d 1, Fel d 2, Fel d 4 in 16.8%, 0.9% and 1.9%. respectively. Sensitisation to fungi and cockroach were rare, except for Bla g 7, to which 16.8% were positive. There was no significant recognition for tree pollens group. For grass, sIgE were detected to Cyn d 1 in 16.8%, Phl p 1 and Phl p 4 in 14.8% and 12.9%, respectively.

CONCLUSION

Knowing that the pattern of allergic sensitisation varies according to environment and population, our results reinforce the need for local studies, using molecular-based diagnosis.

Skin prick/puncture testing in North America: a call for standards and consistency

BACKGROUND

Skin prick/puncture testing (SPT) is widely accepted as a safe, dependable, convenient, and cost-effective procedure to detect allergen-specific IgE sensitivity. It is, however, prone to influence by a variety of factors that may significantly alter test outcomes, affect the accuracy of diagnosis, and the effectiveness of subsequent immunotherapy regimens. Proficiency in SPT administration is a key variable that can be routinely measured and documented to improve the predictive value of allergy skin testing.

METHODS

Literature surveys were conducted to determine the adherence to repeated calls for development and implementation of proficiency testing standards in the 1990's, the mid-2000's and the 2008 allergy diagnostics practice parameters.

RESULTS

Authors publishing clinical research in peer-reviewed journals and conducting workshops at annual scientific meetings have recommended proficiency testing based primarily on its potential to reduce variability, minimize confounding test results, and promote more effective immunotherapeutic treatments. Very few publications of clinical studies, however, appear to report proficiency testing data for SPT performance. Allergen immunotherapy recommendations are updated periodically by the Joint Task Force on Practice Parameters representing the American Academy of Allergy, Asthma and Immunology (AAAAI), the American College of Allergy, Asthma and Immunology (ACAAI), and the Joint Council of Allergy, Asthma and Immunology (JCAAI).

CONCLUSIONS

Despite consensus that all staff who perform SPT should meet basic quality assurance standards that demonstrate their SPT proficiency, the gap between recommendations and daily practice persists. By embracing standards, the accuracy of SPT and allergy diagnosis can be optimized, ultimately benefiting patients with allergic disease.

Population-based study of multiplexed IgE sensitization in relation to asthma, exhaled nitric oxide, and bronchial responsiveness

BACKGROUND

IgE sensitization is an important risk factor for the development of asthma.

OBJECTIVE

The aim of this study was to investigate the IgE antibody profile for a broad spectrum of allergen molecules in asthmatic patients.

METHODS

Participants from the European Community Respiratory Health Survey II (n=467) were tested with ImmunoCAP ISAC against 103 allergen molecules. The presence of bronchial hyperresponsiveness was measured with a methacholine challenge test and bronchial inflammation with fraction of exhaled nitric oxide (Feno).

RESULTS

A total of 38% of the controls and 72% of the asthmatic patients were sensitized against at least 1 of the allergen components (P<.0001). Asthma was independently related to having IgE antibodies against pollen (odds ratio=2.2) and perennial airway allergens (odds ratio=5.6), increased Feno was independently related to having IgE antibodies against food allergens and perennial allergens, while bronchial responsiveness was independently associated with having IgE antibodies against only perennial allergens. Sensitization to food allergens was related to asthma and increased Feno if IgE antibody against pollen allergens was present. Simultaneous sensitization to perennial, pollen, and food allergens involves the highest risk of asthma (odds ratio=18.3), bronchial inflammation, and responsiveness.

CONCLUSIONS

Feno, bronchial responsiveness, and the risk of asthma increase with multiple sensitizations to different allergen groups. We show for the first time that the presence of IgE antibodies against food allergens is independently associated with increased Feno and increases the risk of asthma in subjects with simultaneous sensitization to pollen allergens.

Microarrays: molecular allergology and nanotechnology for personalised medicine (I)

The diagnosis of antibody-mediated allergic disorders is based on the clinical findings and the detection of allergen-specific IgE based on in vitro and in vivo techniques, together with allergen provocation tests. In vitro diagnostic techniques have progressed enormously following the introduction of the advances made in proteomics and nanotechnology--offering tools for the diagnosis and investigation of allergy at molecular level. The most advanced developments are the microarray techniques, which in genomics allowed rapid description of the human genetic code, and which now have been applied to proteomics, broadening the field for research and clinical use. Together with these technological advances, the characterisation of most of the different proteins generating specific IgE and which conform each natural allergen, as well as their purification or genetic engineering-based synthesis, have been crucial elements--offering the possibility of identifying disease-causing allergens at molecular level, establishing a component-resolved diagnosis (CRD), using them to study the natural course of the disease, and applying them to improvements in specific immunotherapy. Microarrays of allergic components offer results relating to hundreds of these allergenic components in a single test, and use a small amount of serum that can be obtained from capillary blood. The availability of new molecules will allow the development of panels including new allergenic components and sources, which will require evaluation for clinical use. The present study reviews these new developments, component-resolved diagnosis, and the development of microarray techniques as a critical element for furthering our knowledge of allergic disease.