The Basophil Activation Test reduces the need for a food challenge test in children suspected of IgE-mediated cow's milk allergy

Comparative analysis of tropomyosin allergenicity in three different species of molluscs: insights into the role of amino acid composition in IgE epitopes

Limited research has been conducted on the differences in allergenicity among Alectryonella plicatula tropomyosin (ATM), Haliotis discus hannai tropomyosin (HTM), and Mimachlamys nobilis tropomyosin (MTM) in molluscs. Our study aimed to comprehensively analyze and compare their immunoreactivity, sensitization, and allergenicity while simultaneously elucidating the underlying molecular mechanisms involved. We assessed the immune binding activity of TM utilizing 86 sera from allergic patients and evaluated sensitization and allergenicity through two different types of mouse models. The dot-blot and basophil activation test assays revealed strong immunoreactivity for HTM, ATM, and MTM, with HTM exhibiting significantly lower levels compared to ATM. In the BALB/c mouse sensitization model, all TM groups stimulated the production of specific antibodies, elicited IgE-mediated immediate hypersensitivity responses, and caused an imbalance in the IL-4/IFN-γ ratio. Similarly, in the BALB/c mouse model of food allergy, all TM variants induced IgE-mediated type I hypersensitivity responses, leading to the development of food allergies characterized by clinical symptoms and an imbalance in the IL-4/IFN-γ ratio. The stimulation ability of sensitization and the severity of food allergies consistently ranked as ATM > MTM > HTM. Through an in-depth analysis of non-polar amino acid frequency and polar hydrogen bonds, HTM exhibited higher frequencies of non-polar amino acids in its amino acid sequence and IgE epitopes, in comparison with ATM and MTM. Furthermore, HTM demonstrated a lower number of polar hydrogen bonds in IgE epitopes. Overall, HTM exhibited the lowest allergenic potential in both allergic patients and mouse models, likely due to its lower polarity in the amino acid sequence and IgE epitopes.

Basophil allergen threshold sensitivity to casein (casein-specific CD-sens) predicts allergic reactions at a milk challenge in most but not all patients

BACKGROUND

The basophil activation test is an emerging clinical tool in the diagnosis of cow's milk allergy (CMA). The aim was to assess the association between the basophil allergen threshold sensitivity to the major milk protein casein (casein-specific CD-sens), the levels of milk- and casein-specific Immunoglobulin E antibodies (IgE-ab), and the severity of allergic reactions at milk challenges.

METHODS

We enrolled 34 patients aged 5-15 (median 9) years who underwent a double-blind placebo-controlled milk-challenge (DBPCMC) as screening before inclusion in an oral immunotherapy study for CMA. The severity of the allergic reaction at the DBPCMC was graded using Sampson's severity score. Venous blood was drawn before the DBPCMC. Milk- and casein-specific IgE-ab were analyzed. Following in vitro stimulation of basophils with casein, casein-specific CD-sens, was determined.

RESULTS

Thirty-three patients completed the DBPCMC. There were strong correlations between casein-specific CD-sens and IgE-ab to milk (rs = 0.682, p < .001), and between casein-specific CD-sens and IgE-ab to casein (rs = 0.823, p < .001). There was a correlation between the severity of the allergic reaction and casein-specific CD-sens level (rs = 0.395, p = .041) and an inverse correlation between casein-specific CD-sens level and the cumulative dose of milk protein to which the patient reacted at the DBPCMC (rs = -0.418, p = .027). Among the 30 patients with an allergic reaction at the DBPCMC, 67% had positive casein-specific CD-sens, 23% had negative casein-specific CD-sens, and 10% were declared non-responders.

CONCLUSION

Two thirds of those reacting at the DBPMC had positive casein-specific CD-sens, but reactions also occurred despite negative casein-specific CD-sens. The association between casein-specific CD-sens and the severity of the allergic reaction and cumulative dose of milk protein, respectively, was moderate.

Basophil activation test in the food allergy clinic: its current use and future applications

INTRODUCTION

The basophil activation test (BAT) has shown evidence of high sensitivity and high specificity to support the diagnosis of IgE-mediated allergy. It is a functional test that uses live cells analyzed by flow cytometry and thus needs to be performed within 24h of blood collection. BAT has shown to be reproducible and reliable when tested in a clinical diagnostic laboratory with standardized protocols and flow cytometry settings.

AREAS COVERED

In this review, we summarize the evidence to support clinical use of BAT and the next steps required for clinical implementation for an improve clinical care for patients with suspected IgE-mediated food allergy.

EXPERT OPINION

BAT has recently been included in Clinical Guidelines of Food Allergy Diagnosis and its implementation in clinical practice depends largely on availability. Proposed clinical applications of the BAT include: distinction between food allergy and asymptomatic IgE sensitization; determination of food allergic status to peanut, tree nuts and seeds in polysensitized children; evaluation of tolerance to baked egg and baked milk in egg and milk allergic children; identification of patients at high-risk of severe allergic reactions; monitoring for spontaneous resolution of food allergy; confirmation of eligibility for specific treatments of food allergy; prediction and monitoring of response to immunomodulatory treatments.

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

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

Indirect Basophil Activation Test for Peanut Allergy Diagnosis Using Human Donor Basophils

The basophil activation test (BAT) is a promising test for the replacement of the expensive, time-consuming, and patient-unfriendly oral food challenge (OFC). However, the BAT requires a fresh blood sample which has to be analyzed within 1 day, which can be a logistical constraint. The indirect or passive basophil activation test (iBAT) with human donor basophils and patient serum that can be stored for a long time (1) enables laboratories to perform the assay at any time, (2) gives the possibility to analyze different allergens in the course of time without the need of a new blood sample, and (3) does not suffer from inconclusive results due to nonresponder basophils. The advantage of this iBAT with human donor basophils over the use of basophil or mast cell lines is that this iBAT can be executed without the need of laboratory facilities for cell culture.

Promises and Remaining Challenges for Further Integration of Basophil Activation Test in Allergy-Related Research and Clinical Practice

More than 20 years after having been initially proposed, the relevance and usefulness of basophil activation test (BAT) for the field of allergy research and testing were demonstrated on many occasions. Leveraging the fully open format of a flexible, whole blood-based functional assay, BAT has been shown to be equally important for fundamental research, clinical research, and diagnosis. Regardless of whether the focus of a study is on the characterization of the allergenic moiety, on the patient side, or on the study of the fundamental processes involved in the allergic disease or its treatment, BAT enables the gathering of very important insights. In spite of this, its full capabilities have yet to be leveraged. Various bottlenecks, including but not limited to assay logistics, robustness, flow cytometry access, and/or expertise, have indeed been limiting its development beyond experts and long-term users. Now, various initiatives, aiming at resolving these bottlenecks, have been launched. If successful, a broader use of BAT could then be contemplated. In such a situation, its more thorough integration in clinical practice has the potential to significantly change the allergic patient's journey.

The Value of Current Laboratory Tests in Diagnosing Food, Venom, and Drug Allergies

An accurate diagnosis of IgE-mediated allergies is necessary to inform risk management for severe allergic reactions including anaphylaxis for food, venom, and drug allergies. The most widely available laboratory test for allergy is serum-specific IgE testing, which is routinely used for food allergy and insect sting allergy. Testing for specific IgE is limited by high sensitivity and low specificity, resulting in concern regarding overdiagnosis. Testing of allergen components has led to improved diagnosis for some food and venom allergens. Additional options for laboratory tests, such as epitope analysis, basophil activation, and mast cell activation, are being investigated for their potential to optimize diagnosis and provide predictors for reaction severity and treatment response. In contrast, laboratory testing for drug allergy is more limited because to date, there are no well-validated commercial assays in the United States. Furthermore, it is important to diagnose delayed reactions to medications, because these also significantly affect decision-making regarding therapeutic options for infectious disorders. Reliable tests for both immediate and delayed drug hypersensitivity are much needed, because drug allergy labels can significantly limit treatment options for patients. Research in this area is emerging.

Update on In Vitro Diagnostic Tools and Treatments for Food Allergies

Food allergy (FA) is an adverse immunological reaction to a specific food that can trigger a wide range of symptoms from mild to life-threatening. This adverse reaction is caused by different immunological mechanisms, such as IgE-mediated, non-IgE-mediated and mixed IgE-mediated reactions. Its epidemiology has had a significant increase in the last decade, more so in developed countries. It is estimated that approximately 2 to 10% of the world's population has FA and this number appears to be increasing and also affecting more children. The diagnosis can be complex and requires the combination of different tests to establish an accurate diagnosis. However, the treatment of FA is based on avoiding the intake of the specific allergenic food, thus being very difficult at times and also controlling the symptoms in case of accidental exposure. Currently, there are other immunomodulatory treatments such as specific allergen immunotherapy or more innovative treatments that can induce a tolerance response. It is important to mention that research in this field is ongoing and clinical trials are underway to assess the safety and efficacy of these different immunotherapy approaches, new treatment pathways are being used to target and promote the tolerance response. In this review, we describe the new in vitro diagnostic tools and therapeutic treatments to show the latest advances in FA management. We conclude that although significant advances have been made to improve therapies and diagnostic tools for FA, there is an urgent need to standardize both so that, in their totality, they help to improve the management of FA.

Allergenicity of partially hydrolyzed whey and casein formulas evaluated by ImmunoCAP inhibition assay and basophil activation test

Background

When exclusive breastfeeding is not possible, partially hydrolyzed formula (PHF) is often used as a starter formula for infants. Some children develop allergic symptoms, including anaphylaxis, after the first intake of cow protein. Therefore, the tolerability of PHF in infants with cow's milk allergy (CMA) is important information. Partially hydrolyzed whey formula (PHWF) is well characterized, but those containing both whey and casein are also available. We evaluated the characteristics of two whey and casein PHFs, PHF1 and PHF2, in vitro and ex vivo, and compared them with a PHWF, PHWF1.

Methods

Residual antigenicity of β-lactoglobulin (β-LG) and casein in the formulas was measured using ELISA. The molecular weight profile was determined using high-pressure liquid chromatography. IgE reactivity and allergenic activity of the formulas were evaluated by ImmunoCAP inhibition assay and by basophil activation test using blood from patients with CMA, respectively.

Results

All the participants (n = 10) had casein-specific IgE. The antigenicity of β-LG in PHF1 was similar to that in PHWF1, but it was slightly higher than that in PHWF1 for casein. PHF1 had a higher IgE reactivity than PHWF1. However, PHF1 and PHWF1 had a similar ability to activate basophils. PHF2 had lower antigenicity of casein and β-LG, IgE reactivity and basophil activation than PHWF1.

Conclusion

These results suggest that the tolerability of PHF1 and PHF2 in patients with CMA is similar to and higher than that of PHWF1, respectively, and that the degree of IgE binding to PHFs does not necessarily correspond to basophil activation.

Current Practice in Pediatric Cow's Milk Protein Allergy-Immunological Features and Beyond

Cow's milk protein allergy is one of the most common pediatric food allergies. It poses a significant socioeconomic burden in industrialized countries and has a profound effect on the quality of life of affected individuals and their families. Diverse immunologic pathways can lead to the clinical symptoms of cow's milk protein allergy; some of the pathomechanisms are known in detail, but others need further elucidation. A comprehensive understanding of the development of food allergies and the features of oral tolerance could have the potential to unlock more precise diagnostic tools and novel therapeutic approaches for patients with cow's milk protein allergy.

EAACI Molecular Allergology User's Guide 2.0

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

Biomarkers in oral immunotherapy

Food allergy (FA) is a global health problem that affects a large population, and thus effective treatment is highly desirable. Oral immunotherapy (OIT) has been showing reasonable efficacy and favorable safety in most FA subjects. Dependable biomarkers are needed for treatment assessment and outcome prediction during OIT. Several immunological indicators have been used as biomarkers in OIT, such as skin prick tests, basophil and mast cell reactivity, T cell and B cell responses, allergen-specific antibody levels, and cytokines. Other novel indicators also could be potential biomarkers. In this review, we discuss and assess the application of various immunological indicators as biomarkers for OIT.

IgE-Mediated food allergy: Current diagnostic modalities and novel biomarkers with robust potential

Food allergy (FA) is a serious public health issue afflicting millions of people globally, with an estimated prevalence ranging from 1-10%. Management of FA is challenging due to overly restrictive diets and the lack of diagnostic approaches with high accuracy and prediction. Although measurement of serum-specific antibodies combined with patient medical history and skin prick test is a useful diagnostic tool, it is still an imprecise predictor of clinical reactivity with a high false-positive rate. The double-blind placebo-controlled food challenge represents the gold standard for FA diagnosis; however, it requires large healthcare and involves the risk of acute onset of allergic reactions. Improvement in our understanding of the molecular mechanism underlying allergic disease pathology, development of omics-based methods, and advances in bioinformatics have boosted the generation of a number of robust diagnostic biomarkers of FA. In this review, we discuss how traditional diagnostic modalities guide appropriate diagnosis and management of FA in clinical practice, as well as uncover the potential of the latest biomarkers for the diagnosis, monitoring, and prediction of FA. We also raise perspectives for precise and targeted medical intervention to fill the gap in the diagnosis of FA.

The Basophil Activation Test for Clinical Management of Food Allergies: Recent Advances and Future Directions

The basophil activation test (BAT) is an ex vivo functional assay that measures by flow cytometry the degree of basophil degranulation after stimulation with an allergen. In recent years, there has been an increased interest in the diagnostic value of the BAT as it has the potential to mimic the clinical phenotype of sIgE sensitized patients, in contrast to allergen-specific IgE levels. This diagnostic potential would be of particular interest for food allergies present early in life such as peanut, cow’s milk and eggs, which require an expensive, time-consuming and patient unfriendly oral food challenge (OFC) for diagnosis. However, routine applications of the BAT for clinical use are not yet feasible due to the lack of standardized protocols and large clinical validation studies. This review will summarize the current data regarding the application of the BAT in food allergy (FA) for cow’s milk, egg and peanut, being the most common causes of FA in children. Additionally, it will discuss the hurdles for widespread clinical use of the BAT and possible future directions for this diagnostic procedure.

Combinatorial advantage of Ses i 1-specific IgE and basophil activation for diagnosis of sesame food allergy

BACKGROUND

The prevalence of sesame food allergy (SFA) is increasing worldwide with the potential of anaphylactic reactions upon exposure. Utility of specific component IgE testing as an alternative to the oral food challenge (OFC), the diagnostic standard, is being investigated.

METHODS

Patients (n = 42) with suspected SFA completed an open OFC to sesame. Diagnostic testing included serum levels of Ses i 1-specific IgE, skin prick test with high-protein extract, and basophil reactivity (% induced CD63 expression) for each patient. The diagnostic utility of these tests was evaluated at a 95% sensitivity, with the outcome measure being the number of OFCs required.

RESULTS

Twenty-seven patients (64%) were diagnosed with SFA. Ses i 1 IgE differed significantly between allergic and tolerant patients (p = .0001). ROC curve analysis for Ses i 1 IgE yielded an AUC of 0.88 ± 0.05. Levels of Ses i 1 IgE correlated to induced CD63+ expression on basophils (p = .0001). Ses i 1 IgE was not sufficiently robust as a single step for diagnosis. Used concurrently, BAT and Ses i 1 IgE yielded correct positive classifications for 25 of 27 sesame-allergic patients with two false positives (93% PPV). Both tests were negative in 5 non-allergic patients. Patients with divergent Ses i 1 IgE and BAT results required OFC (n = 10, 24% of patients). Alternatively, sequential use of BAT, ruling in SFA followed by Ses i 1 IgE diagnosing non-allergic patients, yielded a 89% PPV, with 19% requiring OFC.

CONCLUSION

Ses i 1 IgE and BAT used together can decrease the need for OFC in most SFA patients. A prospective cohort trial is necessary to validate these results.

Basophil activation test in food allergy: is it ready for real-time?

PURPOSE OF REVIEW

Utilization of basophil activation in the diagnosis and monitoring of food allergy has gained increasing recognition. An ex-vivo functional assay, basophil activation reflects clinical reactivity, thereby providing clinically relevant insights. Moreover, as a biomarker of reactivity and tolerance, basophil activation testing (BAT) may provide a useful tool for management of food allergies. Despite its utility, significant limitations of BAT have prevented widespread use. Addressing these limitations will increase the future application and adoption of BAT in food allergy.

RECENT FINDINGS

A number of clinical trials in the past few years have demonstrated the use of BAT in the diagnosis and treatment of food allergy. Specifically, BAT has been found to be a biomarker of tolerance.

SUMMARY

Basophil activation testing is an effective biomarker for diagnosis and monitoring of food allergy.

The Importance of Diet in Predicting the Remission of Urticaria-Determination of Allergen-Specific IgE

Background and Objectives: Different types of food introduced gradually in the diet will expose children to different food allergens, increasing the chance of developing allergic diseases. The aim of our study was to determine if allergen-specific IgE values can influence, depending on the diet, the prediction of remission of urticaria in children. Materials and Methods: This prospective study was conducted in 132 patients diagnosed over two years with urticaria, admitted to "Sf. Maria" Clinical Pediatric Hospital Iaşi. Total IgE assay was performed by ELISA, and determination of specific serum IgE by the CLA System Quanti Scan method (Innogenetics, Heiden, Germany). Data were gathered and statistical analysis was performed using statistical software SPSS, using descriptive and inferential statistics. Results: The determination of specific IgE to food allergens was performed on a total of 132 cases. The values of specific IgE were positive for one or more food allergens in 84 patients (63.64%). The most common allergens involved were: cow's milk in 33.3% cases, egg white in 22.6% cases, and hazelnuts in 11.9% cases. The specific IgE values for the different types of food included in our study had a predictive value for disease remission. Conclusions: The determination of specific IgE confirms the presence of a particular food allergen and may have predictive value for the future development of an allergic manifestation.

Emerging Food Allergy Biomarkers

The management of food allergy is complicated by the lack of highly predictive biomarkers for diagnosis and prediction of disease course. The measurement of food-specific IgE is a useful tool together with clinical history but is an imprecise predictor of clinical reactivity. The gold standard for diagnosis and clinical research is a double-blind placebo-controlled food challenge. Improvement in our understanding of immune mechanisms of disease, development of high-throughput technologies, and advances in bioinformatics have yielded a number of promising new biomarkers of food allergy. In this review, we will discuss advances in immunoglobulin measurements, the utility of the basophil activation test, T-cell profiling, and the use of -omic technologies (transcriptome, epigenome, microbiome, and metabolome) as biomarker tools in food allergy.

Biomarkers of the Severity of Honeybee Sting Reactions and the Severity and Threshold of Systemic Adverse Events During Immunotherapy

BACKGROUND

A biomarker that could identify individuals at high risk for severe honeybee sting allergic reaction and/or systemic adverse events (SAEs) during venom immunotherapy (VIT) would improve the management of patients with honeybee (HB) venom allergy.

OBJECTIVE

To identify biomarkers for risk of severe sting reactions or SAEs during VIT.

METHODS

We recruited 332 patients undergoing HB VIT. We ascertained predictors of the severity of the field-sting reaction and the severity and threshold of SAEs during VIT. We assessed the use of cardiovascular medications; baseline serum tryptase (BST) levels; specific IgEs to HB venom, rApi m 1, and rApi m 10; and basophil activation test (BAT) response.

RESULTS

Significant and independent predictors of a severe HB field-sting reaction were age (P = .008), an absence of skin symptoms (P = .001), BST (P = .014), and BAT response at an HB venom concentration of 0.1 μg/mL (P = .001). Predictors of severe SAEs during HB VIT were age (P = .025), BST (P = .006), and BAT response (P = .001). BAT response was also an individual and significant predictor of any SAEs and SAEs at a low cumulative allergen dose (median, 55 μg) during VIT build-up (P < .001). The use of β-blockers and angiotensin-converting-enzyme inhibitors and specific IgE levels were not associated with the severity of HB field-sting reactions or VIT SAEs.

CONCLUSIONS

BST and basophil activation are independent risk factors for severe HB sting anaphylaxis and SAEs during HB VIT. BAT response was the best biomarker for any SAEs and a lower threshold of SAEs during HB VIT. These risk factors can help guide recommendations for VIT and overcome systemic reactions to HB VIT.

Investigation of Basophil Activation Test for Diagnosing Milk and Egg Allergy in Younger Children

In children with concomitant food allergy and atopic dermatitis (AD), uncovering the causative food allergen is more arduous. We evaluated the basophil activation test (BAT) for its diagnostic value in children, including those with AD, for milk or egg allergy. We simultaneously measured serum-specific immunoglobulin E (sIgE) levels and performed BATs for cow’s milk and egg white. We compared their overall diagnostic performance using the area under the receiver operating characteristic curve (AUC) with the Delong method and compared them in children with AD. Analyses were completed for 75 children for milk allergy and for 85 children for egg allergy. The sIgE and percentage of basophils with the expression of CD63 were correlated for both milk (r = 0.384, p < 0.001) and egg (r = 0.557, p < 0.001). The AUC of sIgE (0.701) for milk allergy was significantly increased when combined with the BAT (0.805; p = 0.029). In children with AD, the AUC of the BAT (0.924) for milk allergy was significantly larger than that of sIgE (0.701; p = 0.017). The BAT is a potentially useful diagnostic tool for milk allergy in children when combined with sIgE. Moreover, it may be a surrogate marker for milk allergy in children with AD.

Developments allergy in 2019 through the eyes of Clinical and Experimental Allergy, Part II clinical allergy

In the second of two linked articles, we describe the development in clinical as described by Clinical & Experimental Allergy and other journals in 2019. Epidemiology, clinical allergy, asthma and rhinitis are all covered. In this article, we described the development in the field of allergy as described by Clinical and Experimental Allergy in 2019. Epidemiology, clinical allergy, asthma and rhinitis are all covered.

Cell-Based Functional IgE Assays Are Superior to Conventional Allergy Tests for Shrimp Allergy Diagnosis

BACKGROUND

The diagnosis of shellfish allergy currently relies on patient history, skin prick test (SPT), and serum specific IgE (sIgE) quantification. These methods lack sufficient diagnostic accuracy, whereas the gold standard of oral food challenges is risky and burdensome. Markers of reactivity and severity of allergic reactions to shellfish will improve clinical care of these patients.

OBJECTIVES

This study compared the diagnostic performance of SPT, sIgE, basophil activation test (BAT), and IgE crosslinking-induced luciferase expression (EXiLE) test for shrimp allergy.

METHODS

Thirty-five subjects with documented history of shrimp allergic reactions were recruited and grouped according to results of double-blind, placebo-controlled food challenge (DBPCFC). In addition to routine diagnostics, BAT (Flow CAST) and EXiLE test with shrimp extract and tropomyosin were performed.

RESULTS

Of 35 subjects, 15 were shrimp allergic with pruritus, urticaria, and itchy mouth on DBPCFC, whereas 20 were tolerant to shrimp. Tropomyosin only accounted for 53.3% of sensitization among subjects with challenge-proven shrimp allergy. BAT using shrimp extract as stimulant showed the highest area under curve value (0.88), Youden Index (0.81), likelihood ratio (14.73), odds ratio (104), and variable importance (4.27) when compared with other assays and tropomyosin diagnosis. Results of BAT significantly correlated with those of EXiLE (r = 0.664, P < .0001).

CONCLUSIONS

BAT is a more accurate diagnostic marker for shrimp allergy than SPT and shrimp sIgE, whereas the EXiLE test based on an IgE crosslinking assay is a good alternative to BAT. Tropomyosin may not be the most important shrimp allergen in Chinese, which warrants further investigation to search for other major allergens and diagnostic markers.

Basophil Activation as Marker of Clinically Relevant Allergy and Therapy Outcome

For some years now the basophil activation test (BAT) using flow cytometry has emerged as a powerful tool and sensitive marker that can be used to detect clinically relevant allergies, provide information on the severity of an allergic reaction, and monitor therapies. Compared to other in vitro diagnostic tests, BAT seems to have a better informative value in terms of clinical relevance. In general, the BAT can be used for the diagnosis of the most common forms of IgE-mediated allergy such as hymenoptera venom allergy, inhalant allergy, food allergy, and drug allergy. Various basophil markers and parameters have been established which, depending on the trigger of the respective allergy, can provide information on the clinical relevance of sensitization, on the development of natural tolerance, on trigger thresholds, and on the severity of the allergic reaction. The BAT also serves as a suitable follow-up instrument for various therapeutic approaches such as specific immunotherapy, desensitization protocols, or use of anti-IgE-antibodies for the various diseases. Quality controls for routine use, standardization, and automatization are expected to expand the range of applications for the above-mentioned indications.

Precision medicine in cow's milk allergy

PURPOSE OF REVIEW

The aim of this review is to describe the role of precision medicine in the diagnosis, treatment, and monitoring of cow's milk allergy.

RECENT FINDINGS

The development of 'omics' sciences in the field of food allergy has led to a better understanding of the allergenicity of cow's milk proteins and significant advances in the knowledge of the pathogenesis and mechanisms of cow's milk allergy. Omics-based technologies allow the practitioner to better differentiate cow's milk allergy subtypes and to predict cow's milk allergy (CMA) persistence over time. Precision medicine extends the role of the oral food challenge, to determine the individual's threshold doses, and to establish tolerance to baked milk products. Other than symptom relief, dietary strategies are currently being investigated for the potential to induce tolerance. Oral immunotherapy offers a treatment option for patients with severe and persistent IgE-mediated CMA. Individual baseline-immune profiles may be predictive of cow's milk oral immunotherapy safety and efficacy.Patient data derived from current technology, in combination with the patient's history, can be translated into treatments targeted at patient-tailored interventions.

SUMMARY

The identification of novel biomarkers may improve diagnostic accuracy and also predict patient responsiveness to treatments. Integration of patient data will become increasingly important as omics technologies become more widely used in the clinical setting.

Oral Food Challenge

Oral food challenge (OFC) is the gold standard for diagnosis of IgE-mediated and non-IgE mediated food allergy. It is usually conducted to make diagnosis, to monitor for resolution of a food allergy, or to identify the threshold of responsiveness. Clinical history and lab tests have poor diagnostic accuracy and they are not sufficient to make a strict diagnosis of food allergy. Higher concentrations of food-specific IgE or larger allergy prick skin test wheal sizes correlate with an increased likelihood of a reaction upon ingestion. Several cut-off values, to make a diagnosis of some food allergies (e.g., milk, egg, peanut, etc.) without performing an OFC, have been suggested, but their use is still debated. The oral food challenge should be carried out by experienced physicians in a proper environment equipped for emergency, in order to carefully assess symptoms and signs and correctly manage any possible allergic reaction. This review does not intend to analyse comprehensively all the issues related to the diagnosis of food allergies, but to summarize some practical information on the OFC procedure, as reported in a recent issue by The Expert Review of Food Allergy Committee of Italian Society of Pediatric Allergy and Immunology (SIAIP).