Usefulness of antigen-specific IgE probability curves derived from the 3gAllergy assay in diagnosing egg, cow's milk, and wheat allergies

Low-dose oral cow's milk challenge outcome for patients on complete avoidance: A multicenter study in Japan

BACKGROUND

Few studies have reported significant risk factors for allergic symptoms during low-dose (1-3 mL) cow's milk (CM) oral food challenges (OFCs). We investigated patients from multiple centers in Japan to identify high-risk, low-dose CM OFCs and conducted these tests at allergy-specialized facilities.

METHODS

We retrospectively collected the results of the first low-dose CM OFCs performed at 10 hospitals in Japan between January and December 2019. All patients completely eliminated CM and underwent low-dose CM OFCs. The risk factors for positive OFC and anaphylaxis were analyzed using logistic regression analyses.

RESULTS

We included 244 patients (median age: 2.5 years). The median level of CM-specific immunoglobulin E (sIgE) was 13.1 (interquartile range: 3.7-45.6) kUA/L. The rates of positive and anaphylaxis among positive for CM OFCs were 44% and 19%, respectively. Multivariate analyses that separately analyzed each sIgE identified high CM sIgE and casein sIgE levels as significant risk factors for OFC positivity (both p < .001). The optimal cut-off values for CM and casein sIgE levels to predict positive CM OFCs from receiver operating characteristic curves were 5.4 and 7.3 kUA/L, respectively. When CM sIgE or casein sIgE levels were ≥10.9 kUA/L or ≥ 11.5 kUA/L, they corresponded to 5% predicted probabilities of anaphylaxis. Furthermore, when their levels are ≥100 kUA/L, the predicted probabilities increase to 20%.

CONCLUSION

CM and casein sIgE levels should be considered when predicting low-dose CM OFC outcomes.

Oral food challenge test results of patients with food allergy with specific IgE levels >100 UA/ml

Specific IgE level (sIgE) is an important factor indicating sensitization status in children with food allergies (FAs). The present study aimed to clarify oral food challenge test (OFC) results in children with FAs with sIgE levels ≥100 UA/ml compared with those in children with sIgE <100. The retrospective study analyzed patients who underwent OFC with egg white, cow milk and wheat at Gifu Prefectural general medical center, Gifu, Japan between July 2017 and March 2023. Clinical history, total IgE (tIgE), sIgE and correlation between sIgE, sIgE/tIgE and eliciting dose as the amount of intake protein were examined. In the <100 group, positive OFC showed significantly higher sIgE for egg white, ovomucoid and casein than negative OFC (P<0.05); however, there was no significant difference between positive and negative OFC in the ≥100 group. In the <100 group, positive OFC showed significantly higher sIgE/tIgE for ovomucoid, milk and casein than negative OFC (P<0.05); however, there was no significant difference in sIgE/tIgE between positive and negative OFC in the ≥100 group. There was a significant negative correlation between eliciting dose and sIgE for egg white and wheat (P<0.05). For milk and wheat, there was no significant difference between ≥100 group and the <100 group with regard to positive rates in the OFC. Therefore, OFC may be safely performed by decreasing total challenge dose for the ≥100 group.

Management of food allergy based on oral food challenge

PURPOSE OF REVIEW

Food allergy is a growing health problem that affects both patients and society in multiple ways. Despite the emergence of novel diagnostic tools, such as component-resolved diagnostics (CRD) and basophil activation tests (BAT), oral food challenge (OFC) still plays an indispensable role in the management of food allergies. This review aimed to highlight the indications and safety concerns of conducting an OFC and to provide insights into post-OFC management based on recent findings.

RECENT FINDINGS

Standardized OFC protocols have regional diversification, especially in Japan and Western countries. Recent studies suggested that the interval between doses should be at least more than an hour. Furthermore, applying a stepwise method tailored to the patient's specific immunoglobulin E level and history of anaphylaxis seems to mitigate these risks. Recent surveys have shown that, following a positive OFC, options other than strict avoidance are also selected.

SUMMARY

OFC serves diverse purposes, yet the risks it carries warrant caution. The stepwise protocol appears promising for its safety. Subthreshold consumption following OFC shows potential; however, further research on its efficacy and safety is required. Management following OFC should be tailored and well discussed between clinicians and patients.

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.

Perinatal Characteristics and the Sensitization to Cow Milk, Egg Whites and Wheat in Children up to 3 Years of Age

Food sensitization in early life identifies children at risk of developing allergic diseases. We investigated the sensitization to cow milk (CM), egg whites, and wheat. Newborns and infants under 3 years of age with available specific immunoglobulin E (sIgE) data were identified. A retrospective survey was conducted using data from the Chang Gung Research Database. Perinatal characteristics, such as singleton or multiples in a single pregnancy, parity, meconium staining, maternal age, spontaneous delivery or cesarean section, meconium passage, weeks of gestation, birth length, body weight, head and chest circumferences, and season, were obtained. The data on sIgE were collected, and a logistic regression model was used to determine the odds of sensitization. Positive sIgE for CM and egg whites was more likely to occur in boys than in girls. Early-life egg white and wheat sensitization was associated with increased birth body length and weight. A multivariate analysis indicated an association between egg white sIgE positivity and logarithmic total IgE. Higher total IgE levels and younger age were associated with egg white sensitization, and elevated weight and length at birth were linked to food sensitization, particularly to egg whites and wheat.

Consensus on the diagnosis and treatment of cow's milk protein allergy of the Latin American Society for Pediatric Gastroenterology, Hepatology and Nutrition

Cow's milk protein allergy (CMPA) is the most frequent cause of food allergy in the first months of life. Despite the fact that there are different guidelines and recommendations on the management of children with CMPA, there continues to be great variability in diagnostic and therapeutic criteria in Latin America. The Food Allergy Working Group of the Latin American Society for Pediatric Gastroenterology, Hepatology and Nutrition summoned a group of Latin American experts to reach a consensus and formulate a document to unify diagnostic and therapeutic criteria for CMPA. Three teams were formed, each with a coordinator, and the members of each team developed a series of statements for their corresponding module: a) clinical manifestations and diagnosis; b) diagnostic tools, and c) treatment. A search of the medical literature was carried out to support the information presented in each module and 28 statements were then selected. The statements were discussed, after which they were evaluated by all the experts, utilizing the Delphi method. Their opinions on statement agreement or disagreement were anonymously issued. The final statements selected were those with above 75% agreement and their corresponding recommendations were formulated, resulting in the document presented herein.

Distinct differences in analytical performance of two commercially available assays for specific IgE to egg white and house dust mite allergens

Background

Measurements of allergen-specific IgE antibodies with different manufacturers’ assays show modest or poor agreement. This study compares analytical performance of specific IgE tests for whole allergen extracts and individual allergen components of two assay systems, IMMULITE and ImmunoCAP, using human sera as well as monoclonal antibodies.

Methods

Comparisons were performed for specific IgE to house dust mite (HDM, n = 44), egg white (EW, n = 36) and the allergen components rDer p 1, rDer p 2, nGal d 1, nGal d 2 and nGal d 4 in human sera and with monoclonal mouse/human chimeric IgE antibodies specific for the same allergen components. Competitive interference with IgE measurement was investigated using allergen-specific monoclonal IgG and IgG4 antibodies.

Results

Measurements of IgE to HDM and EW in serial dilutions of human sera revealed weaker dilution linearity with IMMULITE than with ImmunoCAP. Analysis of five different monoclonal IgE antibodies with total and specific IgE assays, expected to return similar levels, gave an average specific/total IgE ratio of 0.96 (range 0.71–1.14) with ImmunoCAP and 1.89 (range 0.76–2.85) with IMMULITE, indicating overestimation of specific IgE by IMMULITE. With the EW IgE tests of both assay systems, measurements of a chimeric anti-Gal d 2 IgE antibody were unaffected by a competing mouse IgG antibody. While the same was true for measurement of a chimeric anti-Der p 1 IgE antibody using the HDM test in ImmunoCAP, a suppression of measured concentrations by up to 42% was observed in IMMULITE. Similarly, measurement of HDM-specific IgE in human sera by ImmunoCAP was unaffected by a competing monoclonal anti-Der p 2 IgG4 antibody while IMMULITE displayed a reduction of HDM-specific IgE values by up to 30%.

Conclusions

In this evaluation of analytical performance of two widely used assay systems, ImmunoCAP showed higher accuracy in quantitation of specific IgE and greater resistance against competing allergen-specific non-IgE antibodies which may arise through natural or dietary exposure, or as a result of allergen immunotherapy treatment.

Agreement Between Predictive, Allergen-Specific IgE Values Assessed by ImmunoCAP and IMMULITE 2000 3gAllergy™ Assay Systems for Milk and Wheat Allergies

Purpose

ImmunoCAP^® (ImmunoCAP) and IMMULITE^® 2000 3gAllergy™ (3gAllergy) systems are major quantitative allergen-specific immunoglobulin E (sIgE) assay methods. Due to the heterogeneous nature of allergenic extracts and differences in the assay format, quantitation of allergen-sIgEs is not expected to correlate well between different methods. However, we have recently reported good agreement between the methods in the diagnosis of egg allergy. This study aimed to determine and correlate the predictive values of sIgE by the two systems in the diagnosis of milk and wheat allergies.

Methods

Children who had undergone oral food challenge (OFC) for the diagnosis of milk and wheat allergies were enrolled. The OFCs were performed to diagnose either true allergy in the 1-year-old group (A) or tolerance in the 2- to 6-year-old group (B). Milk, casein and β-lactoglobulin, and wheat and ω-5 gliadin sIgE values were measured using the 2 systems. The predictive accuracy of each sIgE for the OFC outcome was assessed using receiver operating characteristic (ROC) curves. The probability of a positive OFC outcome was estimated by logistic regression analysis.

Results

A total of 395 patients were recruited from 7 primary care clinics and 19 hospitals in Japan. Milk and wheat OFCs were performed for 87 and 102 group A patients, and 124 and 82 group B patients, respectively. ROC analysis yielded similar areas under the curve for the 2 assays (0.7–0.9). The log-transformed sIgE data showed a strong linear correlation with the estimated probabilities (R > 0.9).

Conclusions

The 2 systems may be interchangeable for diagnosis of milk and wheat allergies in young children.

Japanese guidelines for food allergy 2020

Five years have passed since the Japanese Pediatric Guideline for Food Allergy (JPGFA) was first revised in 2011 from its original version. As many scientific papers related to food allergy have been published during the last 5 years, the second major revision of the JPGFA was carried out in 2016. In this guideline, food allergies are generally classified into four clinical types: (1) neonatal and infantile gastrointestinal allergy, (2) infantile atopic dermatitis associated with food allergy, (3) immediate-type of food allergy (urticaria, anaphylaxis, etc.), and (4) special forms of immediate-type of food allergy such as food-dependent exercise-induced anaphylaxis and oral allergy syndrome (OAS). Much of this guideline covers the immediate-type of food allergy that is seen during childhood to adolescence. Infantile atopic dermatitis associated with food allergy type is especially important as the onset of most food allergies occurs during infancy. We have discussed the neonatal and infantile gastrointestinal allergy and special forms of immediate type food allergy types separately. Diagnostic procedures are highlighted, such as probability curves and component-resolved diagnosis, including the recent advancement utilizing antigen-specific IgE. The oral food challenge using a stepwise approach is recommended to avoid complete elimination of causative foods. Although oral immunotherapy (OIT) has not been approved as a routine treatment by nationwide insurance, we included a chapter for OIT, focusing on efficacy and problems. Prevention of food allergy is currently the focus of interest, and many changes were made based on recent evidence. Finally, the contraindication between adrenaline and antipsychotic drugs in Japan was discussed among related medical societies, and we reached an agreement that the use of adrenaline can be allowed based on the physician's discretion. In conclusion, this guideline encourages physicians to follow the principle to let patients consume causative foods in any way and as early as possible.

How to diagnose food allergy

PURPOSE OF REVIEW

To assess the recent studies that focus on specific immunoglobulin E (sIgE) testing and basophil activation test (BAT) for diagnosing IgE-mediated food allergies.

RECENT FINDINGS

The sIgE to allergen extract or component can predict reactivity to food. The cutoff value based on the positive predictive value (PPV) of sIgE can be considered whenever deciding whether oral food challenge (OFC) is required to diagnose hen's egg, cow's milk, wheat, peanut, and cashew nut allergy. However, PPV varies depending on the patients' background, OFC methodology, challenge foods, and assay methodology. Component-resolved diagnostics (CRD) has been used for food allergy diagnosis. Ovomucoid and omega-5 gliadin are good diagnostic markers for heated egg and wheat allergy. More recently, CRD of peanut, tree nuts, and seed have been investigated. Ara h 2 showed the best diagnostic accuracy for peanut allergy; other storage proteins, such as Jug r 1 for walnut, Ana o 3 for cashew nut, Ses i 1 for sesame, and Fag e 3 for buckwheat, are also better markers than allergen extracts. Some studies suggested that BAT has superior specificity than skin prick test and sIgE testing.

SUMMARY

The sIgE testing and BAT can improve diagnostic accuracy. CRD provides additional information that can help determine whether OFCs should be performed to diagnose food allergy.

Specific IgE for Fag e 3 Predicts Oral Buckwheat Food Challenge Test Results and Anaphylaxis: A Pilot Study

BACKGROUND

Buckwheat (BW) is the source of a life-threatening allergen. Fag e 3-specific serum IgE (sIgE) is more useful than BW-sIgE for diagnosis; however, it is unknown whether Fag e 3-sIgE can predict oral food challenge (OFC) results and anaphylaxis. This study aimed to clarify the efficacy of Fag e 3-sIgE in predicting OFC results and anaphylaxis.

METHODS

We conducted a retrospective review of BW- and Fag e 3-sIgE data obtained using the ImmunoCAP® assay system and fluorescent enzyme-linked immunosorbent assay from children who underwent OFC using 3,072 mg of BW protein between July 2006 and March 2014 at Sagamihara National Hospital, Kanagawa, Japan.

RESULTS

We analyzed 60 patients aged 1.9-13.4 years (median 6.0 years); 20 (33%) showed objective symptoms upon BW OFC. The patients without symptoms had significantly lower Fag e 3-sIgE than those with non-anaphylactic (p < 0.001) and anaphylactic reactions to BW (p = 0.004). Fag e 3-sIgE was the only tested factor that significantly predicted positive OFC results (odds ratio 8.93, 95% confidence interval 3.10-25.73, p < 0.001) and OFC-induced anaphylaxis (2.67, 1.12-6.35, p = 0.027). We suggest that a threshold Fag e 3-sIgE level of 18.0 kUE/L has 95% probability of provoking a positive reaction to BW.

CONCLUSIONS

Fag e 3-sIgE predicted OFC results and OFC-induced anaphylaxis. We further emphasize paying careful attention to the risk of BW OFC-induced anaphylaxis.

Skin prick test is more useful than specific IgE for diagnosis of buckwheat allergy: A retrospective cross-sectional study

BACKGROUND

Buckwheat (BW) is a potentially life-threatening allergen. Usefulness of BW-specific immunoglobulin-E (BW-sIgE) level for diagnosis of BW allergy is controversial, while the skin prick test (SPT) is widely used because of its less invasive procedure and immediate results. However, there are no data comparing usefulness of the SPT and BW-sIgE level. Therefore, our study aimed to clarify efficacy of the SPT for diagnosis of BW allergy.

METHODS

This retrospective cross-sectional study evaluated patients who underwent an oral food challenge (OFC) for diagnosis or confirmation of acquired tolerance using 3072 mg of BW protein between July 2006 and April 2014. We then compared the diagnostic performance of BW sIgE and SPT to predict positive OFC results.

RESULTS

We analyzed 126 patients aged 2-16 years (median, 7.7 years), 18 (14%) of whom showed positive OFC results. Between patients with positive and negative OFC results, there was no significant difference in BW-sIgE level. However, patients with positive OFC results had a larger SPT wheal diameter. Area under the curve for positive OFC results for BW-sIgE level and SPT wheal diameter were 0.583 and 0.791, respectively. The 5%, 10%, 50%, and 90% positive predictive values of SPT wheal diameter were 2.0 mm, 5.2 mm, 14.7 mm, and 24.1 mm, respectively.

CONCLUSIONS

Our study revealed that the SPT was more useful than BW-sIgE level for diagnosis of BW allergy. Thus, an OFC may be avoided if the patient's SPT wheal diameter is at least 24.1 mm.

Japanese guidelines for food allergy 2017

Five years have passed since the Japanese Pediatric Guideline for Food Allergy (JPGFA) was first revised in 2011 from its original version. As many scientific papers related to food allergy have been published during the last 5 years, the second major revision of the JPGFA was carried out in 2016. In this guideline, food allergies are generally classified into four clinical types: (1) neonatal and infantile gastrointestinal allergy, (2) infantile atopic dermatitis associated with food allergy, (3) immediate-type of food allergy (urticaria, anaphylaxis, etc.), and (4) special forms of immediate-type of food allergy such as food-dependent exercise-induced anaphylaxis and oral allergy syndrome (OAS). Much of this guideline covers the immediate-type of food allergy that is seen during childhood to adolescence. Infantile atopic dermatitis associated with food allergy type is especially important as the onset of most food allergies occurs during infancy. We have discussed the neonatal and infantile gastrointestinal allergy and special forms of immediate type food allergy types separately. Diagnostic procedures are highlighted, such as probability curves and component-resolved diagnosis, including the recent advancement utilizing antigen-specific IgE. The oral food challenge using a stepwise approach is recommended to avoid complete elimination of causative foods. Although oral immunotherapy (OIT) has not been approved as a routine treatment by nationwide insurance, we included a chapter for OIT, focusing on efficacy and problems. Prevention of food allergy is currently the focus of interest, and many changes were made based on recent evidence. Finally, the contraindication between adrenaline and antipsychotic drugs in Japan was discussed among related medical societies, and we reached an agreement that the use of adrenaline can be allowed based on the physician's discretion. In conclusion, this guideline encourages physicians to follow the principle to let patients consume causative foods in any way and as early as possible.