Utility of food allergy thresholds

The Allergy Crossroads of Subtropical Regions: Mites, Crustaceans, and the Rise of Edible Insects

Background: Edible insects (EIs) are increasingly recognized as a sustainable protein source, yet concerns persist regarding allergic reactions, even in individuals without prior known consumption. This study examines the immune response profile in patients from a subtropical area to improve understanding of mite-related cross-reactivity and emerging food sensitizations. Methods: To assess sensitization to edible insects, we analyzed 634 patients from a tertiary care allergy institution with high perennial exposure to house dust mites and storage mites. Sensitization patterns were assessed using the ALEX²® MacroArray platform, a multiplex IgE diagnostic tool covering 282 allergens, including Locusta migratoria (Lm), Acheta domesticus (Ad), and T. molitor (Tm). Patients with IgE levels ≥0.3 kU/L were evaluated for cross-reactivity to both mite allergens and pan-allergens. Results: Of the 634 patients, 138 (21.76%) exhibited IgE sensitization to at least one EI extract. Tropomyosin was the most prevalent pan-allergen (63.76%), followed by troponin-C (28.98%) and arginine kinase (26.81%). Notably, 95.66% of EI-sensitized individuals also reacted to mite allergens. However, 23.18% lacked reactivity to common pan-allergens, suggesting alternative sensitization mechanisms. Conclusions: This investigation can highlight regional variations in EI sensitization, where high mite exposure in subtropical climates appears to influence IgE responses to insect proteins. The findings suggest that EI sensitization is not merely incidental but represents a distinct immunological phenomenon shaped by environmental factors and allergen cross-reactivity. Since the presence of food-specific IgE does not reliably indicate clinical allergy, and the lack of food challenge data constrains diagnostic certainty, acknowledging EI sensitization as a potential risk factor remains essential for ensuring food safety and protecting public health.

Persistence, Severity, and Reactivity Thresholds in Fish-Allergic Patients Sensitized to Parvalbumin

BACKGROUND

Fish allergy affects children and adults worldwide, and there are transient and persistent phenotypes.

OBJECTIVE

We aimed to analyze persistence, severity, and reactivity thresholds in challenge-confirmed fish-allergic patients sensitized to parvalbumin.

METHODS

Patients 12 to 65 years old reporting immediate reactions to fish, with fish skin prick test ≥5 mm and IgE to cod and carp β-parvalbumins ≥0.70 kUA/L, were recruited in 6 European centers. Except for the case with recent severe anaphylaxis, patients were eligible for a double-blind placebo-controlled food challenge with cod, followed, if negative, by an open food challenge. Severity of reported and elicited reactions was graded with the Food Allergy Severity Score, eliciting dose (ED) was calculated using interval-censoring survival analysis and probabilistic models, and factors associated with a positive challenge and severe reactions were analyzed by logistic regression.

RESULTS

Of 42 patients fulfilling inclusion criteria, fish allergy was confirmed in 30 (71.4%) patients. The median fish allergy duration was 23 years. Although 70% of cases reported anaphylaxis with respiratory or cardiovascular involvement, food challenges resulted in oropharyngeal symptoms (34.7%) or mild systemic reactions (73.9%), with only 1 anaphylaxis with bronchospasm (4.3%). Male sex was associated with severe reactions (odds ratio: 5.44, 95% confidence interval: 1.04-28.53). ED10 for objective symptoms was 0.99 to 2.54 mg of protein. No correlation was found between severity and ED.

CONCLUSIONS

Adolescents and adults with persistent fish allergy linked to parvalbumin sensitization have experienced severe allergic reactions in real life and have a low threshold of reactivity. Our findings support the need for large-scale studies and new therapeutic options for these fish-allergic patients.

Microbial metabolism of food allergens determines the severity of IgE-mediated anaphylaxis

Anaphylaxis is an acute, potentially life-threatening reaction, often triggered by foods and largely mediated by IgE. A critically important aspect of anaphylaxis pertains to the factors that modulate its severity. The human microbiota is known to influence oral tolerance, but the microbial mechanisms directly involved in IgE-mediated anaphylaxis remain unknown. Here, we demonstrate that human saliva harbors peanut-degrading bacteria that metabolize immunodominant allergens (Ara h 1 and Ara h 2) and alter IgE binding. Additionally, we provide in vivo evidence showing that oral bacteria metabolize peanut allergens, influencing systemic allergen exposure and the severity of anaphylaxis. Finally, in a clinical study, we observe that common peanut-degrading bacteria, such as Rothia, from the oral cavity, are more abundant in peanut-allergic patients who exhibit better tolerance to allergen exposure. Altogether, these results demonstrate the role of the human microbiota in modulating IgE-mediated reactions through allergen metabolism. These findings reveal a novel microbial mechanism with potential to prevent, or reduce, the severity of IgE-mediated anaphylaxis.

Identifying thresholds of reaction for different foods

Current food allergy management universally treats all patients with food allergy as being at risk for anaphylaxis (with the exception perhaps of pollen food allergy syndrome). Thus, patients are told to avoid the allergenic food in all potentially allergic forms and amounts. However, research over the past 2 decades has shown that many patients will tolerate small amounts of the allergen without any allergic reaction. Thus, if one were able to identify the threshold of reactivity, this could change management. At the population level, establishing levels at which the vast majority of patients (e.g., 95%) do not react could have public health ramifications, such as altering labeling laws. At the individual patient level, personal threshold levels could determine avoidance strategies, affect quality of life, and alter treatment decisions, e.g., oral immunotherapy starting doses. In this review, threshold data for various allergens and their potential effect on the management of the patient with food allergy are examined.