Relationship between serum allergen-specific immunoglobulin E and threshold dose in an oral food challenge

Three-year prognoses after low-dose oral food challenge for cow's milk

BACKGROUND

Low-dose (LD) oral food challenge (OFC) with heated cow's milk (CM; 3 mL) effectively prevents CM elimination in children with CM allergy (CMA). We investigated the long-term prognoses after an LD-OFC for CMA.

METHODS

Children with immediate CMA symptoms after consuming <25 mL of CM within 2 years of a baseline LD-OFC were retrospectively analyzed. Children who successfully passed the baseline LD-OFC (LD-passing) continued consuming 3 mL of CM at home, whereas those who failed (LD-failing) continued to avoid CM. Dose escalation occurred through stepwise OFCs or gradually at home. CM tolerance was defined as the ability to repeatedly consume ≥100 mL CM without experiencing symptoms; the inability to do so indicated persistent CMA. The prognoses of the LD-passing and LD-failing groups within 3 years of LD-OFC were compared.

RESULTS

Among 113 children, the median age at baseline LD-OFC was 2.8 years; 41 % had an anaphylaxis history, with equal distribution between the LD-passing and LD-failing groups. Three years later, 63 % and 5 % of children demonstrated CM tolerance in the LD-passing and LD-failing groups, respectively (p < 0.001). In the LD-passing group, predictors of persistent CMA were older age (adjusted hazard ratio [95 % confidence interval], 1.37 [1.00-1.88]), higher CM-specific IgE level (2.95 [1.30-6.68]) and other food allergies (2.34 [1.12-4.90]).

CONCLUSIONS

Failure in LD-OFC is associated with persistent CMA, whereas successful LD-OFC outcomes are associated with a favorable prognosis thereafter, irrespective of a history of anaphylaxis.

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.

AAAAI-EAACI PRACTALL: Standardizing oral food challenges-2024 Update

This common statement of the American Academy of Allergy, Asthma and Immunology (AAAAI) and The European Academy of Allergy and Clinical Immunology (EAACI) provides an update of the 2012 published guidelines on food challenges. The guidelines equally address food challenges in the research and the clinical settings. They first address the diagnostic tests which can guide the decision to conduct a challenge. Safety of food challenges is prime, and the various procedures and safety issues as well as medications potentially involved in challenges are extensively discussed. Challenges are suggested to be conducted with semi-logarithmic incremental doses based on the protein content, typically for IgE-mediated food allergy with intervals of 20-30 min between doses. Specific protocols for other types of reactions such atopic dermatitis or gastrointestinal food allergy are detailed separately. Proper stopping criteria are essential in order to reduce the risk of false-positive diagnoses, but also severe reactions. The guidelines recommend criteria based on "go on," "stop," or "observation." These revised guidelines will clearly provide much needed guidance for food challenges in the research and clinical settings. They will continue to evolve with new diagnostic tests or new needs in the field of food allergy.

Accidental allergic reactions to immediate-type food allergens in Japanese children: A single-center study

BACKGROUND

Few studies have assessed the nature of accidental allergic reactions (AAR). We assessed the prevalence and risk factors for AAR in Japanese children.

METHODS

This study included children with immediate-type hen's egg (HE), cow's milk (CM), wheat, or peanut allergy who developed allergic reactions within at least 2 years and were followed up regularly at a single national allergy center in Japan. From January to December 2020, low-dose reactivity was defined as allergic reactions to ≤250, ≤102, ≤53, or ≤ 133 mg of HE, CM, wheat, or peanut protein, respectively. The annualized AAR rate showed the number of reactions per patient per year (95% confidence interval). AAR risk factors were analyzed using multiple logistic regression.

RESULTS

Of the 1096 participants, 609, 457, 138, and 90 had HE, CM, wheat, and peanut allergies, respectively. The median (interquartile range) age was 5.0 (2.3-8.6) years, 39% had completely eliminated allergenic food, and 24% had low-dose reactivity. The annualized AAR rate was 0.130 (0.109-0.153) in all sub-cohorts. Moderate and severe symptoms occurred in 50% and 0.7%, respectively, of children who experienced AAR. Multiple logistic regression revealed that low-dose reactivity was a significant risk factor for AAR in the overall and CM cohorts, respectively (p < .001 and p = .036).

CONCLUSION

In this single-center study in Japan, the annualized AAR rate was relatively low during the COVID-19 pandemic; however, half of the participants with AAR had moderate to severe symptoms. Especially in the case of low-dose reactivity, children would require careful AAR risk management.

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.

Peanut oral immunotherapy using an extensively heated and baked novel composition of peanuts

BACKGROUND

Oral immunotherapy (OIT) is an increasingly acceptable therapeutic option for peanut-allergic (PA) children, despite significant side effects. Major peanut allergenic proteins are heat-resistant and are not rendered hypoallergenic after baking or cooking. Lyophilized peanut protein-MH (LPP-MH) is a novel composition from developing peanuts, enabling cooking-induced reduction in allergenicity. We aimed to explore the safety and efficacy of OIT, with extensively heated and baked (EHEB) LPP-MH in PA children.

METHODS

In a single-arm, single-center, pilot study, PA children with a single highest tolerated dose of <100 mg peanut protein were placed on a 40-week OIT protocol with 300 mg daily of heat-treated LPP-MH. A repeat open peanut food challenge was performed after 40 weeks of treatment and at a 6-12 months of follow-up visit.

RESULTS

Thirty-three children with PA were enrolled, with a mean cumulative tolerated dose (MCTD) of 71.2 mg PP (95% CI 45-100 mg). After 40 weeks, 32/33 patients were able to consume more than 300 mg of natural PP, with MCTD of 1709 mg (CI 365-3675 mg). There were no severe allergic reactions requiring epinephrine, during any of the observed LPP-MH challenges or any treatment related doses at home. After 6-12 months on daily maintenance, the MCTD was 8821 mg (95% CI 1930-13,500 mg). This enabled most children age-appropriate dietary inclusion of peanuts.

CONCLUSION

An OIT protocol with heat-treated LPP-MH, a novel composition from developing peanuts, seems a potentially safe and efficacious OIT modality for PA children, enabling the introduction of dietary levels of peanut proteins in highly allergic PA children. Validation in randomized controlled studies is mandated.

Timing of initial symptom onset during milk and wheat challenges: A retrospective study

BACKGROUND

Allergic reactions to milk appear sooner than those to hen's eggs, irrespective of the total dose of the oral food challenges (OFCs) and type of matrices. The reported median times for the first symptom occurrence are 20-30 min with milk and 50-60 min with eggs. However, allergic reactions due to wheat have not yet been fully investigated.

METHODS

This study retrospectively collected data from OFC for milk and wheat conducted at Sagamihara National Hospital and Sendai Medical Center from 2009 to 2023. The time from the start of the OFC to the onset of symptoms was compared between children with cow's milk and wheat allergy.

RESULTS

Twenty-five and 13 children reacted to single-dose OFCs with milk products equivalent to 25 mL of raw cow's milk or 15 g of udon noodles, respectively. The median ages of patients with positive challenges were 1.4 and 2.8 years for milk and wheat, respectively, and the median times for the first symptom occurrence were 20 min and 53 min, respectively (p = .006).

CONCLUSION

This multicenter study was the first to examine the time of symptom appearance during single-medium-dose milk and wheat challenges. Allergic reactions to wheat appear later than those for milk during OFC. For multiadministration OFC for wheat, the dosing interval should be longer than 60 min. Our findings can help improve the safety of OFCs.

Relationship between eliciting doses and the severity of allergic reactions to food

PURPOSE OF REVIEW

Food allergies with low thresholds are associated with frequent accidental allergic reactions. Severe reactions attributable to accidental ingestion often result in a poor quality of life. Nevertheless, no evidence of a relationship between a low threshold dose and the severity of symptoms exists. Therefore, we evaluated recent data regarding the threshold of food allergies based on the oral food challenge (OFC). We also proposed a stepwise OFC method to identify threshold and consumable doses.

RECENT FINDINGS

A higher specific IgE level and a history of food-induced anaphylaxis were related to low threshold doses and severe reactions during the OFC. In addition, a low threshold dose was not directly correlated with severe reactions. Performing a stepwise OFC may help safely clarify consumable doses and prevent the complete avoidance of allergy-causing foods.

SUMMARY

Severe food allergies with high specific IgE levels are associated with lower thresholds and more severe reactions. However, the threshold is not directly related to the severity of food-induced allergic symptoms. Identifying a well tolerated consumable dose using a stepwise OFC may help manage food allergies.