Sesame: An Increasingly Popular Word and Common Food Allergen

Sesame allergy in children: New insights into diagnosis and management

Sesame is a potentially potent allergen that can trigger skin, gastrointestinal, and respiratory tract symptoms, and anaphylaxis. Only 20% to 30% of sesame-allergic children develop tolerance. The prevalence of sesame allergy depends on local diets and ranges from 0.1% to 0.9%. A high risk of accidental exposure to sesame has resulted in mandatory food labeling in many countries. More than half of patients with sesame allergy are also allergic to peanut/tree nuts. Serum-specific IgE testing with a quantitative Ses i 1 component can be performed safely and has higher clinical specificity and better positive predictive value for oral food challenge (OFC) than whole sesame extract or skin prick testing (SPT). Compared with SPT or OFC, in vitro Ses i 1 testing requires no special techniques and carries no risk of reactions. Diagnosis of suspected sesame allergy begins with a thorough history and physical examination. A positive sesame extract test (≥0.1 kUA /L) should prompt further testing. In patients with a high probability of reacting, results of component testing may facilitate a decision about performing an OFC. In a Japanese study of OFC and Ses i 1, there was a 5% probability of a positive OFC with Ses i 1 sIgE levels <0.13 kUA /L, and a 50% probability of a positive OFC with levels >32.0 kUA /L. Most patients could safely consume sesame if sIgE levels were <0.13 kUA /L. Ses i 1 testing can be used to guide appropriate management (avoidance, emergency medication, and oral immunotherapy).

Sesame allergy: mechanisms, prevalence, allergens, residue detection, effects of processing and cross-reactivity

Sesame allergy is a serious public health problem and is mainly induced by IgE-mediated reactions, whose prevalence is distributed all over the world. Sesame has been included on the priority allergic food list in many countries. This review summarizes the mechanism and prevalence of sesame allergy. The characteristics, structures and epitopes of sesame allergens (Ses i 1 to Ses i 7) are included. Moreover, the detection methods for sesame allergens are evaluated, including nucleic-acid, immunoassays, mass spectrometry, and biosensors. Various processing techniques for reducing sesame allergenicity are discussed. Additionally, the potential cross-reactivity of sesame with other plant foods is assessed. It is found that the allergenicity of sesame is related to the structures and epitopes of sesame allergens. Immunoassays and mass spectrometry are the major analytical tools for detecting and quantifying sesame allergens in food. Limited technologies have been successfully used to reduce the antigenicity of sesame, involving microwave heating, high hydrostatic pressure, salt and pH treatment. More technologies for reducing the allergenicity of sesame should be widely investigated in future studies. The reduction of allergenicity in processed sesames should be ultimately confirmed by clinical studies. What's more, sesame may exhibit cross-reactivity with peanut and tree nuts.

A practical focus on sesame allergy and a brief review of other seed allergies

Although seed allergies are relatively rare, sesame allergy has been increasing worldwide and is typically persistent in most patients. Because allergen labeling laws, until just recently, have not required the declaration of sesame as a major allergen, there is a clear need to better understand and potentially treat this food allergy. Although blood and skin prick testing for sesame have limited predictive value, this improves with the use of component diagnostics and skin-prick test with fresh sesame. A thorough history and oral food challenge should be used to diagnose sesame allergy. Treatment of sesame allergy with oral immunotherapy has been demonstrated to be safe and effective in case reports, and in at least one controlled study with a published sesame oral immunotherapy protocol. There is minimum literature with regard to management of other seed allergies.

Clinical experience with sesame oral immunotherapy and a quality-of-life assessment

Background

Allergic reactions to sesame have increased in prevalence in the United States. Sesame oral immunotherapy (OIT) is an emerging management strategy. Few reports assessed the benefits and risks of sesame OIT in children with sesame allergy.

Objective

To study the adverse events and quality of life (QoL) on sesame OIT in a U.S. population.

Methods

Twenty-three patient charts were retrospectively reviewed from 2017 to 2020. The patients received a validated Food Allergy Quality of Life Questionnaire and a survey on adverse reactions during maintenance therapy. Patients who were 8.5 ± 4.7 years of age (30% girls and 70% boys) with a documented history of sesame allergy and who had undergone sesame OIT were reviewed.

Results

The buildup phase was 293.7 ± 87.1 days. Twenty-one of the 23 patients (91.3%) reached maintenance therapy. Twenty-one patients (91.3%) had at least one gastrointestinal reaction; 18 (78.3%) had at least one cutaneous reaction; 6 (26%) had at least one respiratory reaction. Age raised the odds of gastrointestinal reactions more than fivefold (odds ratio [OR] 5.653 (95% confidence interval [CI], 2.409 - 13.269); p = 0.0009). Asthma boosted the odds of respiratory reactions of more than ninefold (OR 9.206 [95% CI, 1.535 - 55.211]; p = 0.0187). Female gender increased the odds of having a respiratory reaction by more than sevenfold (OR 7.545 [95% CI, 1.207 - 47.153]; p = 0.0330). Asthma amplified the odds of cutaneous reactions (OR 11.725 [95% CI, 2.390 - 57.517]; p = 0.0053). Three patients ultimately discontinued therapy. Food-related anxiety (-0.773) and social/dietary limitation (-0.687) improved significantly in QoL.

Conclusion

Sesame OIT may be safe and easily adaptable to private practice and significantly improves QoL. Further prospective studies would be helpful to fully assess these relationships.

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.